APY (Annual Percentage Yield) tells you how much interest you'll earn on a deposit account over one year, including compound interest. APR (Annual Percentage Rate) tells you the cost of borrowing money, including fees. Banks use APY for savings accounts and APR for loans and credit cards. Both are expressed as percentages, but they measure opposite sides of the same transaction.
APY: What You Earn
When a high-yield savings account advertises "4.5% APY," that number includes the effect of compounding. Your interest earns its own interest, so your actual return over a year is slightly higher than the base rate.
Here's a concrete example. You deposit $10,000 in an account with a 4.5% nominal rate that compounds daily:
- Month 1: You earn about $37.50 in interest
- Month 2: You earn interest on $10,037.50, not just $10,000
- By month 12: Your balance is approximately $10,460
That 4.5% nominal rate actually produces about 4.60% APY thanks to daily compounding. The difference is small on modest balances but meaningful when you're saving larger amounts over longer periods.
Key Takeaways
- APY = what you earn (savings, CDs, money market accounts)
- APR = what you pay (loans, credit cards, mortgages)
- APY includes compounding, APR typically doesn't
- Higher APY on savings = better for you
- Lower APR on loans = better for you
APR: What You Pay
APR is the annualized cost of a loan or credit product. When your credit card charges 22% APR, that's the yearly interest rate applied to your unpaid balance. APR also includes certain fees, like origination fees on personal loans or mortgage points.
One critical difference: APR on credit cards compounds. If you carry a balance, the interest charges get added to your principal, and next month you pay interest on that larger amount. This is why credit card debt grows so fast.
Side-by-Side Comparison
| Feature | APY | APR |
|---|---|---|
| Measures | Interest earned | Interest owed |
| Includes compounding | Yes | Usually no (except credit cards) |
| Used for | Savings, CDs, MMAs | Loans, credit cards, mortgages |
| Higher is better? | Yes (more earnings) | No (more cost) |
| Regulated by | Truth in Savings Act | Truth in Lending Act |
Why This Matters When Comparing Accounts
Always compare savings accounts using APY, not the nominal interest rate. Two banks might both advertise "4.5% interest," but one compounds daily while the other compounds monthly. The daily-compounding account produces a higher APY and earns you more money over time.
Similarly, when comparing loans, look at APR rather than just the interest rate. A mortgage with a 6.5% rate and high origination fees might have a higher APR than a mortgage with a 6.75% rate and no fees. The CFPB explains this distinction clearly for mortgage shoppers.
The Compounding Frequency Effect
How often interest compounds affects APY. Here's what $10,000 earns at a 4.5% nominal rate with different compounding frequencies:
- Annual compounding: $10,450.00 (APY = 4.50%)
- Monthly compounding: $10,459.09 (APY = 4.59%)
- Daily compounding: $10,460.52 (APY = 4.60%)
Most online banks and money market accounts compound daily, which is ideal for savers. Always check the compounding frequency in the account's fine print.
Bottom Line
When you're saving, focus on APY. When you're borrowing, focus on APR. Both numbers standardize the way financial products present their rates so you can make genuine comparisons. Ignore the marketing and look at the actual percentages.