"APR vs APY: The Difference That Costs (or Earns) You Money"
Contents
APR and APY differ by a single letter and a world of meaning. Confusing them leads people to underestimate what debt costs and overestimate what savings earn. Here's how to tell them apart and use each correctly.
The one-line difference
- APR (Annual Percentage Rate) is the simple yearly rate, ignoring intra-year compounding.
- APY (Annual Percentage Yield) is the effective yearly rate, including the effect of compounding.
Because compounding always adds a little (or a lot), APY is always equal to or higher than the APR it's based on. They're only identical when interest compounds exactly once a year.
Why compounding creates the gap
Suppose a rate of 12% APR that compounds monthly. Each month you earn (or owe) 1%. But that 1% is added to the balance, so next month's 1% is charged on a slightly larger amount. Over twelve months, 12% APR compounded monthly works out to about 12.68% APY. The extra 0.68% is compounding doing its quiet work. The more frequently interest compounds — monthly, daily, continuously — the wider the gap between the stated APR and the true APY.
Why lenders quote APR and banks quote APY
This isn't an accident; it's marketing physics:
- Lenders (credit cards, loans) quote APR because it's the lower number. A card advertised at "19.99% APR" actually costs about 21.9% APY once monthly compounding is included. The APR makes the debt look cheaper than it is.
- Banks (savings accounts, CDs) quote APY because it's the higher number. Advertising the effective yield makes the return look as good as possible.
So both industries quote the number that flatters them. Once you know this, you can mentally adjust: assume debt costs a bit more than its APR, and don't be fooled when a savings APY looks slightly better than a competitor's APR — you may be comparing different things.
How to compare fairly
The golden rule: compare like with like. When shopping for savings accounts, compare APY to APY. When comparing loans, compare APR to APR — and ideally the APR that includes fees, which is what regulators require lenders to disclose precisely so borrowers can compare total cost, not just the interest rate.
A subtlety on loans: the regulatory APR also folds in mandatory fees (origination charges, points), which is why a loan's APR can exceed its stated interest rate. That makes APR genuinely useful for comparing loan offers — a low-rate loan with high fees can have a higher APR than a higher-rate loan with no fees.
Where it bites in real life
- Credit cards: the "daily periodic rate" means card debt compounds daily. A 24% APR is roughly a 27% APY — one reason balances grow faster than people expect. See what that costs with our credit card payoff calculator.
- Savings and CDs: two accounts with the same nominal rate but different compounding frequencies earn different amounts. The APY captures the real return, so it's the honest basis for choosing.
- Loans with fees: always ask for the APR including fees to compare offers on total cost rather than headline rate.
Quick reference
| APR | APY | |
|---|---|---|
| Includes compounding? | No | Yes |
| Usually quoted by | Lenders | Banks |
| Which is bigger? | Lower | Higher (or equal) |
| Best for comparing | Loans | Savings |
Convert it yourself
The math is simple enough to do on any calculator. To turn an APR into an APY:
APY = (1 + APR/n)ⁿ − 1, where n is the number of compounding periods per year.
For 12% APR compounded monthly (n = 12): (1 + 0.12/12)¹² − 1 = (1.01)¹² − 1 ≈ 0.1268 = 12.68% APY. Compounded daily (n = 365) it edges up to about 12.75%. Going the other way — from a quoted APY back to the nominal APR — is rarer but occasionally useful: APR = n × [(1 + APY)^(1/n) − 1].
A fast sanity check without any formula: the higher the rate and the more frequent the compounding, the bigger the APR-to-APY gap. At low savings rates (say 1%) the difference is a rounding error; at credit-card rates (20%+) compounding daily, it's several full percentage points — which is exactly why card balances snowball. Our APY calculator does the conversion instantly if you'd rather not do the arithmetic.
Bottom line
APR is the sticker rate; APY is what actually happens after compounding. Debt costs a little more than its APR suggests, and savings compound to a little more than a nominal rate implies. Compare loans by APR, savings by APY, and never let a single-letter difference cost you money you didn't have to lose.