SmartRateToolsYou've seen both terms everywhere — on credit card offers, savings account ads, mortgage quotes. APR. APY. They look almost identical and sound interchangeable. They're not.
Understanding the difference can save you real money — especially when shopping for loans or comparing savings accounts. Here's the short version, and then the full breakdown.
The one-sentence version
- APR (Annual Percentage Rate) — the cost of borrowing money, per year, not counting compounding.
- APY (Annual Percentage Yield) — the actual return on savings or the real cost of debt, including compounding.
APY is always higher than APR when the interest rate is the same, because APY accounts for the snowball effect of compounding. Lenders use APR to make loans look cheaper. Banks use APY to make savings accounts look more attractive. Both moves are technically accurate — and both are designed to favor the institution.
What is APR?
APR is the annual interest rate on a loan or credit card, expressed as a simple percentage. It doesn't account for how often interest compounds. It may include some fees (like origination fees on mortgages) but often doesn't capture the full picture.
For example: a credit card with a 24% APR charges 2% per month (24 ÷ 12). But because you're charged on your running balance, the actual annualized cost is higher than 24% once compounding is factored in. That's where APY comes in.
What is APY?
APY accounts for compounding — the effect of earning (or paying) interest on top of previously accumulated interest. It shows you what a rate actually works out to over a full year when compounding is baked in.
The formula is: APY = (1 + r/n)^n - 1, where r is the nominal interest rate and n is the number of compounding periods per year.
For a savings account with a 5% APR compounded monthly:
- n = 12 (monthly compounding)
- APY = (1 + 0.05/12)^12 - 1 ≈ 5.12%
Not a huge difference at low rates — but it becomes significant on large balances or high interest rates.
When does it matter?
Savings accounts and CDs
When comparing savings accounts or certificates of deposit, always compare APYs. Banks are required to disclose APY, and it's the true measure of what you'll earn. A bank advertising "5% interest" might mean 5% APR — the actual APY with monthly compounding would be 5.12%.
Credit cards
Credit cards quote APR. But because balances compound monthly (if you carry a balance), the effective annual rate is actually higher than the stated APR. A 24% APR credit card effectively costs you about 26.8% APY if you carry a balance all year.
This is why carrying a credit card balance is so expensive — and why paying it off in full every month effectively makes the APR meaningless (no compounding, no interest paid).
Mortgages
Mortgage rates are typically quoted as APR (and sometimes include lender fees). For fixed-rate mortgages, the difference between APR and APY is small — compounding effects are spread over 30 years and the math is somewhat different since you're paying down principal continuously. When comparing mortgages, APR is still the more useful comparison number, as long as you're comparing apples to apples on the fee inclusions.
Quick reference
When you see a rate quoted somewhere, use this cheat sheet:
- Borrowing (loans, credit cards, mortgages) → they'll show APR. The real cost is slightly higher due to compounding.
- Saving/investing (savings accounts, CDs, money market) → they'll show APY. This is the actual return you'll receive.
- When comparing options, always compare the same metric — don't compare one account's APR to another's APY.
The bottom line
APR and APY measure the same underlying interest rate — but APY bakes in compounding while APR doesn't. For savings, higher APY is better. For loans, lower APR is better — but be aware the true cost is slightly above the stated APR.
The most important habit: compare like with like. If you're shopping savings accounts, compare APYs. If you're comparing loan offers, compare APRs. And always read the fine print on what fees are or aren't included.
Want to see how compounding plays out in your own investment scenario? Try the compound interest calculator and adjust the compounding frequency to see how it affects your final balance.