Unit Economics For Founders Practice Exam

Question 1 Unit Economics For Founders

What is annual contract value (ACV)?

The number of months of gross profit from a new customer required to recover the CAC spent to acquire them. The annualized revenue from a customer contract, used to normalize multi-year deals for unit economics. Customers pay per unit of consumption (API calls, GB stored, messages sent); aligns revenue with cost and value delivered. The number of new users each existing user brings in; k > 1 means viral exponential growth. Rare in B2B, more common in consumer.

Question 2 Unit Economics For Founders

What is the break-even conversion rate?

The minimum free-to-paid conversion at which the blended LTV of the free cohort equals the CAC; below this, growth destroys value. The ratio of Daily Active Users to Monthly Active Users; measures "habit strength" — Facebook famously targets > 50%. The months until a new rep hits full quota productivity; ramped productivity is critical to sustainable CAC math. The percentage of free users who become paying customers; a small number (1–5% is common) but multiplied by huge free-user volume drives paid growth.

Question 3 Unit Economics For Founders

What is logo churn?

The ratio of Daily Active Users to Monthly Active Users; measures "habit strength" — Facebook famously targets > 50%. The percentage of customer accounts that cancel in a period, regardless of contract size; measures customer count loss. The minimum price at which a unit is still profitable, typically set by variable cost plus desired contribution margin. A go-to-market motion where users discover, try, and adopt a product with minimal sales involvement, often via free trial or freemium.

Question 4 Unit Economics For Founders

What is the difference between top-down and bottom-up forecasting?

LTV divided by CAC; the canonical measure of per-unit return on acquisition spend. Healthy SaaS startups target ≥ 3:1. Top-down: start with market size and take a share. Bottom-up: multiply channels × conversion × ARPU. Bottom-up is more reliable for unit economics. Land with a small initial contract, then grow usage/footprint inside the account; relies on net negative churn mechanics. Gross churn is total revenue lost to cancellations and downgrades; net churn subtracts expansion revenue from the same cohort, often producing a negative net churn.

Question 5 Unit Economics For Founders

What is customer concentration risk?

When a few customers represent a large share of revenue; their churn disproportionately destroys LTV and ARR. The percentage of signups who reach the activation event within a defined window — the first conversion of signup to engaged user. Low upfront cost, linear with spend, fast feedback, high marginal CAC at scale. Easy to start, easy to overspend. Customers pay per user/seat with a flat subscription; predictable revenue but misaligned with actual value consumption.

Question 6 Unit Economics For Founders

What is the difference between CAC and CRC?

CAC = Cost to Acquire a Customer. CRC = Cost to Retain (or Serve) a Customer. Both are fully loaded and both matter for LTV math. The sensitivity of unit demand to price changes; inelastic demand lets you raise price and grow per-unit profit without losing volume. Because spending on acquisition before proving a unit is profitable at scale mathematically guarantees greater losses; growth amplifies whatever margin profile already exists. Starting ARR minus churn and contraction, divided by starting ARR; excludes upsell. The "floor" of retention health.

Question 7 Unit Economics For Founders

What is the conversion rate from free to paid?

The monthly version of ARR: sum of all recurring contracts' monthly value; ARR = MRR × 12. Any countable resource: an API call, a stored gigabyte, a transaction, a generated token. The billable metric. 60–90% take-rate × underlying margin; the marketplace's own gross margin can be very high even if GMV margins are low. The percentage of free users who become paying customers; a small number (1–5% is common) but multiplied by huge free-user volume drives paid growth.

Question 8 Unit Economics For Founders

What is Contribution Margin?

Revenue minus all variable costs directly tied to producing/serving that unit, expressed per unit or as a percentage. David Sacks, in a 2020 tweet-thread, framing it as "the SaaS metric that matters most in 2020." Contribution margin is more useful for unit economics because it excludes fixed costs and isolates what each incremental unit adds to profit. A go-to-market motion where users discover, try, and adopt a product with minimal sales involvement, often via free trial or freemium.

Question 9 Unit Economics For Founders

What is unit economics?

> 85% annually is acceptable; > 90% is good; enterprise SaaS targets > 95%. The incremental cost to produce or serve one additional unit; central to pricing and contribution margin. The percentage of recurring revenue lost in a period, including downgrades; measures dollar loss. The revenue and costs directly attributable to a single unit of value (e.g., one customer, one transaction, one subscription month) used to assess per-unit profitability.

Question 10 Unit Economics For Founders

What is a sales pipeline coverage ratio?

The incremental cost to produce or serve one additional unit; central to pricing and contribution margin. Multi-year deals increase LTV proportionally (no churn between years) and dramatically improve LTV:CAC, but introduce collection and credit risk. The months until a new rep hits full quota productivity; ramped productivity is critical to sustainable CAC math. The ratio of open pipeline value to quota; typically 3–4× is required to reliably hit a number.

Question 11 Unit Economics For Founders

What is a fully-loaded CAC?

Payback measures time to recover CAC (a cash-flow question); LTV:CAC is the long-run ratio (a profitability question). Both must be healthy. David Sacks, in a 2020 tweet-thread, framing it as "the SaaS metric that matters most in 2020." The total gross profit a customer is expected to generate over the entire future relationship with the company. CAC that includes the share of marketing, sales, and overhead salaries (not just ad spend) attributable to acquiring one customer.

Question 12 Unit Economics For Founders

What is DAU/MAU?

60–90% take-rate × underlying margin; the marketplace's own gross margin can be very high even if GMV margins are low. LTV divided by CAC; the canonical measure of per-unit return on acquisition spend. Healthy SaaS startups target ≥ 3:1. The ratio of Daily Active Users to Monthly Active Users; measures "habit strength" — Facebook famously targets > 50%. When revenue from a unit exceeds the variable cost to produce/serve it, meaning every additional sale improves total profit.

Question 13 Unit Economics For Founders

What is the difference between gross churn and net churn?

Because users who never activate have near-zero LTV, so increasing activation rate directly increases effective LTV without spending more on acquisition. Gross churn = total revenue lost to cancels + downgrades; net churn = gross churn minus expansion. Net can be negative. Multi-year deals increase LTV proportionally (no churn between years) and dramatically improve LTV:CAC, but introduce collection and credit risk. Because all per-unit operating costs (R&D, G&A, S&M) must be paid from gross profit; low margin means scale cannot reach profitability.

Question 14 Unit Economics For Founders

Why is activation critical to unit economics?

A scenario where each customer technically pays back (LTV > CAC) but slowly — long payback periods tie up capital and break under interest rates. Usage drop, support tickets, NPS decline, payment failures, missing a milestone; lagging indicators (cancellation) are too late to act. Customers pay per user/seat with a flat subscription; predictable revenue but misaligned with actual value consumption. Because users who never activate have near-zero LTV, so increasing activation rate directly increases effective LTV without spending more on acquisition.

Question 15 Unit Economics For Founders

What is the universally cited "magic number" for LTV:CAC?

3:1 — the standard benchmark for healthy SaaS unit economics. Hosting, support, abuse, fraud, and dev time amortized per free user; often $0.10–$5/month depending on product. A scenario where each customer technically pays back (LTV > CAC) but slowly — long payback periods tie up capital and break under interest rates. CAC = Cost to Acquire a Customer. CRC = Cost to Retain (or Serve) a Customer. Both are fully loaded and both matter for LTV math.

Question 16 Unit Economics For Founders

What is the unit economics of paid ads?

A common rule: no single customer > 10% of ARR; an enterprise SaaS audit red flag. The monthly version of ARR: sum of all recurring contracts' monthly value; ARR = MRR × 12. Low upfront cost, linear with spend, fast feedback, high marginal CAC at scale. Easy to start, easy to overspend. The total gross profit a customer is expected to generate over the entire future relationship with the company.

Question 17 Unit Economics For Founders

How do fixed costs affect unit economics?

Sales Magic Number = net new ARR in a quarter ÷ sales & marketing spend in the prior quarter; > 0.75 means invest more in S&M. When revenue from a unit exceeds the variable cost to produce/serve it, meaning every additional sale improves total profit. Below 1:1 means each customer loses money; 1–2:1 is fragile and below investor expectations for venture-scale software. Fixed costs don't change unit economics directly, but high fixed costs mean scale is required to reach per-unit profitability — making low CAC and high LTV existential.

Question 18 Unit Economics For Founders

What is the unit in usage-based pricing?

Any countable resource: an API call, a stored gigabyte, a transaction, a generated token. The billable metric. > 120%; some reach 130–140%+, meaning existing customers grow even as some churn. The point at which spending more in an acquisition channel yields diminishing returns; the marginal CAC rises above LTV. The sensitivity of unit demand to price changes; inelastic demand lets you raise price and grow per-unit profit without losing volume.

Question 19 Unit Economics For Founders

What are variable costs?

The percentage of free users who become paying customers; a small number (1–5% is common) but multiplied by huge free-user volume drives paid growth. Costs that scale linearly (or near-linearly) with units produced or sold: hosting, payment processing, transaction fees, per-user support time. The percentage of GMV (Gross Merchandise Value) a marketplace retains as revenue; central to marketplace unit economics. Additional recurring revenue from existing customers via upsells, cross-sells, seat growth, or usage increases.

Question 20 Unit Economics For Founders

What is contraction revenue?

The unit volume at which total revenue equals total costs; below this, the business loses money per period; above, it profits. David Sacks, in a 2020 tweet-thread, framing it as "the SaaS metric that matters most in 2020." Revenue lost when existing customers downgrade their plan, reduce seats, or lower usage tier. The process of retrying failed payments and contacting customers to fix billing; can recover 30–50% of involuntary churn.

Question 21 Unit Economics For Founders

What gross margin is typical for SaaS?

When revenue from a unit exceeds the variable cost to produce/serve it, meaning every additional sale improves total profit. 70–85% once mature; early-stage SaaS often sits 50–70% as hosting and support costs scale with customers. Gross Merchandise Value — the total dollar volume of transactions processed through a marketplace; marketplace revenue is take-rate × GMV. Sales Magic Number = net new ARR in a quarter ÷ sales & marketing spend in the prior quarter; > 0.75 means invest more in S&M.

Question 22 Unit Economics For Founders

What GRR is considered acceptable for SMB SaaS?

Gross profit subtracts all costs of goods sold; contribution margin subtracts only variable costs tied to that unit. For unit decisions, contribution margin is sharper. > 85% annually is acceptable; > 90% is good; enterprise SaaS targets > 95%. Revenue minus all variable costs directly tied to producing/serving that unit, expressed per unit or as a percentage. A SaaS company's growth rate plus profit margin should exceed 40% (e.g., 30% growth + 10% margin) for a healthy balance of growth and efficiency.

Question 23 Unit Economics For Founders

How does take-rate relate to LTV in marketplaces?

Fixed costs don't change unit economics directly, but high fixed costs mean scale is required to reach per-unit profitability — making low CAC and high LTV existential. LTV ≈ take-rate × GMV per user × gross margin on each transaction × customer lifespan; low take-rate must be offset by high frequency or high GMV. Activation is the user experiencing product value (often free); conversion is the user paying — both required for revenue LTV. A customer whose fully-loaded cost to serve exceeds their revenue; every additional month they stay deepens the loss.

Question 24 Unit Economics For Founders

What is the price elasticity relevant to unit economics?

The monthly version of ARR: sum of all recurring contracts' monthly value; ARR = MRR × 12. The sensitivity of unit demand to price changes; inelastic demand lets you raise price and grow per-unit profit without losing volume. A customer whose fully-loaded cost to serve exceeds their revenue; every additional month they stay deepens the loss. Because spending on acquisition before proving a unit is profitable at scale mathematically guarantees greater losses; growth amplifies whatever margin profile already exists.

Question 25 Unit Economics For Founders

What is a payment processing fee?

A variable cost (typically 2.5–3.5%) charged per transaction by Stripe/Adyen etc., which must be included in unit-economics math. Free users have a cost (hosting) and conversion probability; paid LTV must exceed blended CAC including the cost of the free cohort over its lifespan. LTV typically uses gross profit per period, not revenue, so a 50% gross margin halves the customer's lifetime value vs revenue-based math. Costs that scale linearly (or near-linearly) with units produced or sold: hosting, payment processing, transaction fees, per-user support time.

Question 26 Unit Economics For Founders

What is the difference between gross profit and contribution margin?

GMV is the total value of goods sold through the platform; revenue is the platform's slice (fees, commissions, ads), not the whole transaction value. A cohort retention curve that dips then rises — typical of products with a learning curve, where power users become more engaged over time. Gross profit subtracts all costs of goods sold; contribution margin subtracts only variable costs tied to that unit. For unit decisions, contribution margin is sharper. 60–90% take-rate × underlying margin; the marketplace's own gross margin can be very high even if GMV margins are low.

Question 27 Unit Economics For Founders

What is activation?

The unit volume at which total revenue equals total costs; below this, the business loses money per period; above, it profits. The total gross profit a customer is expected to generate over the entire future relationship with the company. The first moment a new user experiences the core value of the product; a key step between signup and retention. Multi-year deals increase LTV proportionally (no churn between years) and dramatically improve LTV:CAC, but introduce collection and credit risk.

Question 28 Unit Economics For Founders

What is a k-factor?

The rate at which consumer subscription customers cancel by stopping payment; common in B2C, less so in B2B. The number of new users each existing user brings in; k > 1 means viral exponential growth. Rare in B2B, more common in consumer. The revenue and costs directly attributable to a single unit of value (e.g., one customer, one transaction, one subscription month) used to assess per-unit profitability. The sensitivity of unit demand to price changes; inelastic demand lets you raise price and grow per-unit profit without losing volume.

Question 29 Unit Economics For Founders

What is negative net churn?

When expansion revenue from existing customers exceeds churned revenue, the base grows without new sales — a hallmark of best-in-class SaaS. Land with a small initial contract, then grow usage/footprint inside the account; relies on net negative churn mechanics. Activation is the user experiencing product value (often free); conversion is the user paying — both required for revenue LTV. CAC that includes the share of marketing, sales, and overhead salaries (not just ad spend) attributable to acquiring one customer.

Question 30 Unit Economics For Founders

What gross margin is typical for marketplaces?

A common rule: no single customer > 10% of ARR; an enterprise SaaS audit red flag. The fully-loaded cost to acquire one new paying customer, including ad spend, sales salaries, tools, and creative, divided by new customers in the period. Any countable resource: an API call, a stored gigabyte, a transaction, a generated token. The billable metric. 60–90% take-rate × underlying margin; the marketplace's own gross margin can be very high even if GMV margins are low.

Question 31 Unit Economics For Founders

What CAC payback period do investors consider healthy in SaaS?

Under 12 months; best-in-class B2B SaaS achieves under 12, often cited as < 18 months as acceptable. The first moment a new user experiences the core value of the product; a key step between signup and retention. Gross Merchandise Value — the total dollar volume of transactions processed through a marketplace; marketplace revenue is take-rate × GMV. A group of users sharing a defined start event (e.g., customers acquired in January 2025) tracked over time to measure behavior.

Question 32 Unit Economics For Founders

What is Gross Revenue Retention (GRR)?

Starting ARR minus churn and contraction, divided by starting ARR; excludes upsell. The "floor" of retention health. Sales-led = high-touch, high CAC, enterprise ACV; product-led = low-touch, low CAC, SMB ACV. Unit economics differ by an order of magnitude. A group of users sharing a defined start event (e.g., customers acquired in January 2025) tracked over time to measure behavior. The first moment a new user experiences the core value of the product; a key step between signup and retention.

Question 33 Unit Economics For Founders

What is channel saturation?

Additional recurring revenue from existing customers via upsells, cross-sells, seat growth, or usage increases. The months until a new rep hits full quota productivity; ramped productivity is critical to sustainable CAC math. The point at which spending more in an acquisition channel yields diminishing returns; the marginal CAC rises above LTV. Voluntary = customer chooses to leave. Involuntary = payment failure (expired card, insufficient funds). Involuntary can be recovered with dunning.

Question 34 Unit Economics For Founders

What is GMV?

Gross Merchandise Value — the total dollar volume of transactions processed through a marketplace; marketplace revenue is take-rate × GMV. Logo churn signals customer dissatisfaction; revenue churn captures financial impact. They can diverge wildly — losing small customers is fine, losing whales is fatal. When revenue from a unit exceeds the variable cost to produce/serve it, meaning every additional sale improves total profit. The point at which spending more in an acquisition channel yields diminishing returns; the marginal CAC rises above LTV.

Question 35 Unit Economics For Founders

What is a seat-based pricing model?

Customers pay per user/seat with a flat subscription; predictable revenue but misaligned with actual value consumption. Revenue is top-line; gross profit subtracts COGS. Unit economics almost always uses gross profit (contribution margin) per unit. A customer still on the books but with near-zero engagement and at high risk of churning; a drag on support cost and an LTV depressor. A multiple of ARR or revenue (e.g., 10× ARR for SaaS) used to back-solve what LTV:CAC and growth must be to justify a target valuation.

Question 36 Unit Economics For Founders

What is the unit economics of a content/SEO channel?

The process of retrying failed payments and contacting customers to fix billing; can recover 30–50% of involuntary churn. 20–50% depending on category; thin margins make CAC efficiency existential. Gross Merchandise Value — the total dollar volume of transactions processed through a marketplace; marketplace revenue is take-rate × GMV. High upfront fixed cost, near-zero marginal CAC per lead, long payback. Great at scale but slow to ramp; suffers if churn is high.

Question 37 Unit Economics For Founders

What is the activation rate?

The first moment a new user experiences the core value of the product; a key step between signup and retention. The percentage of signups who reach the activation event within a defined window — the first conversion of signup to engaged user. Gross churn is total revenue lost to cancellations and downgrades; net churn subtracts expansion revenue from the same cohort, often producing a negative net churn. Average Revenue Per User (or per customer/per account); total revenue divided by customer count, used as a unit-level revenue measure.

Question 38 Unit Economics For Founders

What is a ramped vs non-ramped CAC?

CAC that includes the share of marketing, sales, and overhead salaries (not just ad spend) attributable to acquiring one customer. The fully-loaded cost to acquire one new paying customer, including ad spend, sales salaries, tools, and creative, divided by new customers in the period. A SaaS company's growth rate plus profit margin should exceed 40% (e.g., 30% growth + 10% margin) for a healthy balance of growth and efficiency. Non-ramped CAC ignores ramp time and understates cost; ramped CAC amortizes ramp cost over the rep's productive months.

Question 39 Unit Economics For Founders

What is marginal CAC?

Activation is the user experiencing product value (often free); conversion is the user paying — both required for revenue LTV. Land with a small initial contract, then grow usage/footprint inside the account; relies on net negative churn mechanics. The CAC of the next incremental customer, not the average. If marginal CAC > LTV, the channel is exhausted for that audience/creative. Gross churn = total revenue lost to cancels + downgrades; net churn = gross churn minus expansion. Net can be negative.

Question 40 Unit Economics For Founders

What is the break-even point?

Fixed costs don't change unit economics directly, but high fixed costs mean scale is required to reach per-unit profitability — making low CAC and high LTV existential. Payback measures time to recover CAC (a cash-flow question); LTV:CAC is the long-run ratio (a profitability question). Both must be healthy. The unit volume at which total revenue equals total costs; below this, the business loses money per period; above, it profits. Revenue lost when existing customers downgrade their plan, reduce seats, or lower usage tier.

Question 41 Unit Economics For Founders

What is the unit economics of virality?

When revenue from a unit exceeds the variable cost to produce/serve it, meaning every additional sale improves total profit. ARPU averages revenue per active user/account over a period; ASP (Average Selling Price) is the mean price of a single transaction or contract. Free users have a cost (hosting) and conversion probability; paid LTV must exceed blended CAC including the cost of the free cohort over its lifespan. Each user acquisition costs near-zero in cash but is paid for in product experience (friction, incentives); k-factor is the key metric.

Question 42 Unit Economics For Founders

What is the "burning platform" unit economics warning?

When a business is unprofitable per unit but funds growth with capital; the only path to breakeven is dramatically improving LTV or reducing CAC — both hard. Net new ARR added by existing customers in a period via upsell, cross-sell, or seat increases. Customers pay per unit of consumption (API calls, GB stored, messages sent); aligns revenue with cost and value delivered. Enterprise: high ACV, high CAC, long sales cycle, low churn, multi-year contracts. SMB: low ACV, low CAC, short sales cycle, higher churn %, monthly contracts.

Question 43 Unit Economics For Founders

What is the difference between SMB and Enterprise unit economics?

Enterprise: high ACV, high CAC, long sales cycle, low churn, multi-year contracts. SMB: low ACV, low CAC, short sales cycle, higher churn %, monthly contracts. CAC that includes the share of marketing, sales, and overhead salaries (not just ad spend) attributable to acquiring one customer. Gross churn is total revenue lost to cancellations and downgrades; net churn subtracts expansion revenue from the same cohort, often producing a negative net churn. The number of months of gross profit from a new customer required to recover the CAC spent to acquire them.

Question 44 Unit Economics For Founders

What is a "negative churn" SaaS business?

A steep drop in the first weeks, then a long, flat tail; the goal is to make that long tail as high as possible. A SaaS where expansion MRR from existing customers exceeds churned MRR every month, so net new ARR from the existing book is positive even with zero new sales. Low upfront cost, linear with spend, fast feedback, high marginal CAC at scale. Easy to start, easy to overspend. 20–50% depending on category; thin margins make CAC efficiency existential.

Question 45 Unit Economics For Founders

What is the difference between payback and LTV:CAC?

ARPU averages revenue per active user/account over a period; ASP (Average Selling Price) is the mean price of a single transaction or contract. Total cost of a sales rep (base, commission, benefits, manager, tools, office) divided by customers or ARR they close, used in CAC. A steep drop in the first weeks, then a long, flat tail; the goal is to make that long tail as high as possible. Payback measures time to recover CAC (a cash-flow question); LTV:CAC is the long-run ratio (a profitability question). Both must be healthy.

Question 46 Unit Economics For Founders

What is a credit card churn?

Cohorts isolate acquisition-channel quality and product-market fit; blended metrics hide deteriorating economics masked by newer, better cohorts. The percentage of customer accounts that cancel in a period, regardless of contract size; measures customer count loss. The rate at which consumer subscription customers cancel by stopping payment; common in B2C, less so in B2B. The point at which spending more in an acquisition channel yields diminishing returns; the marginal CAC rises above LTV.

Question 47 Unit Economics For Founders

What is dunning?

The process of retrying failed payments and contacting customers to fix billing; can recover 30–50% of involuntary churn. Paid CAC isolates the cost of a customer from a specific paid channel; blended CAC divides all acquisition spend (including organic-attributed overhead) by all new customers. The CAC of the next incremental customer, not the average. If marginal CAC > LTV, the channel is exhausted for that audience/creative. Any countable resource: an API call, a stored gigabyte, a transaction, a generated token. The billable metric.

Question 48 Unit Economics For Founders

What is the Quick Ratio in SaaS?

The incremental cost to produce or serve one additional unit; central to pricing and contribution margin. Revenue lost when existing customers downgrade their plan, reduce seats, or lower usage tier. Voluntary = customer chooses to leave. Involuntary = payment failure (expired card, insufficient funds). Involuntary can be recovered with dunning. (New + Expansion MRR) ÷ (Churned + Contraction MRR) in a period; above 4 is excellent, below 2 is weak.

Question 49 Unit Economics For Founders

What is paid CAC vs blended CAC?

Net burn divided by net new ARR; measures capital efficiency. A burn multiple under 1.0 is excellent, 1.0–1.5 acceptable, > 2.0 inefficient. Customers pay per unit of consumption (API calls, GB stored, messages sent); aligns revenue with cost and value delivered. Paid CAC isolates the cost of a customer from a specific paid channel; blended CAC divides all acquisition spend (including organic-attributed overhead) by all new customers. Retention is the percentage of customers who stay over a period; churn is the percentage who leave. They sum to 100% in a closed cohort.

Question 50 Unit Economics For Founders

What is a fully loaded salesperson cost?

The revenue and costs directly attributable to a single unit of value (e.g., one customer, one transaction, one subscription month) used to assess per-unit profitability. Total cost of a sales rep (base, commission, benefits, manager, tools, office) divided by customers or ARR they close, used in CAC. Top-down: start with market size and take a share. Bottom-up: multiply channels × conversion × ARPU. Bottom-up is more reliable for unit economics. The minimum free-to-paid conversion at which the blended LTV of the free cohort equals the CAC; below this, growth destroys value.