Why Your Savings Account Loses Money

Why the balance can climb while wealth falls

A savings account can lose purchasing power while the balance grows, because the interest rate the bank quotes is almost always lower than the rate at which prices in the economy are rising. When that gap exists, every dollar in the account buys a little less each year than it did the year before, even as the dollar count on the statement moves up.

The mechanism is straightforward. Inflation is a rise in the general price level: a basket of goods that cost $100 last year costs about $103 this year if inflation runs at 3 percent. Cash held in a savings account does not itself produce goods; it only claims them. So if the claim grows by 2 percent while the prices of what it can claim grow by 3 percent, the real purchasing power of the claim has fallen.

A concrete example

Suppose you deposit $10,000 in an account paying 2 percent annually, and inflation runs at 3 percent per year. After five years, with interest compounded, the balance is about $11,041. The nominal gain looks healthy. But if the same basket of goods that cost $10,000 initially now costs about $11,593, then your $11,041 buys roughly what $9,524 bought five years earlier. The dollar balance is up; what the balance can actually purchase is down.

For small rates, the real return is often approximated as the nominal rate minus the inflation rate. The exact formula is: real return = (1 + nominal rate) / (1 + inflation rate) − 1. Using the exact version with 2 percent and 3 percent gives about −0.97 percent per year, very close to the simple subtraction but slightly less harsh.

The common misunderstanding

The mix-up is equating a rising balance with rising wealth. A bank statement reports dollars; wealth is what those dollars can purchase. Those two questions have different answers whenever the inflation rate exceeds the interest rate, and conflating them is how people end up surprised that their savings feels worth less at the end of a decade than at the start, despite earning interest every year.

When this reasoning does not apply

• Inflation is very low or negative. If prices are flat or falling, any positive nominal rate is also a positive real rate, and savings genuinely grow in purchasing power.
• The funds must remain liquid. An emergency reserve that may be needed within days or weeks has to sit in cash or near-cash. A negative real return is better than being unable to pay an unexpected bill.
• The horizon is short. Over a few months, the gap between nominal and real is usually small enough to ignore.
• Your spending basket differs from the inflation measure. Official indexes reflect an average household. If most of your spending is in categories whose prices rose faster than the headline number, your personal inflation rate is higher and the loss is larger than any single figure suggests.