The Difference Between Interest Rate and APY
When a bank advertises a savings account, you will typically see two numbers: an interest rate and an APY. They sound similar but measure different things — and mixing them up can lead you to underestimate or overestimate what your money will actually earn.
The interest rate is the basic annual percentage the bank pays on your deposit, calculated without factoring in how often that interest is added to your balance. The APY (Annual Percentage Yield) goes one step further: it reflects how much you will earn over a full year including the effect of compounding. Because compounding builds on itself, APY is almost always higher than the raw interest rate — and it is the more accurate figure to use when comparing accounts.
APY Is the Number That Actually Matters
When you see two accounts advertised at different rates, always compare their APYs — not the base interest rates. Because APY accounts for how often interest compounds, it gives you an apples-to-apples view of what you will actually earn over a year. Federal law (under the Truth in Savings Act) requires banks to disclose APY clearly before you open an account.
For a broader introduction to how savings accounts work overall, see Savings Accounts, Explained.
| What APY stands for | Annual Percentage Yield |
| APY vs. interest rate | APY includes compounding; the interest rate does not |
| Most common compounding frequency | Daily or monthly |
| Rate type on most savings accounts | Variable — can change at any time |
| Key number to compare across accounts | APY — it reflects true annual earnings |
| Federally insured deposit limit (FDIC) | $250,000 per depositor, per bank, per category (Federal Deposit Insurance Corporation (FDIC)) |
How Compound Interest Works — and Why Frequency Matters
Compound interest means you earn interest not just on your original deposit but also on the interest you have already accumulated. Over short periods the difference looks small; over years it becomes meaningful.
Here is a simple illustration. Suppose you deposit $1,000 at a 5% annual interest rate:
- Simple interest (no compounding): You earn exactly $50 at year's end — 5% of $1,000.
- Monthly compounding: The bank divides 5% by 12, adds that fraction to your balance each month, then calculates the next month's interest on the new total. You end the year with slightly more than $50.
- Daily compounding: The same logic applied 365 times a year yields a marginally higher result still.
The more frequently interest compounds, the higher the effective APY — even if the stated interest rate is identical across accounts. This is why two accounts can advertise the same rate but deliver slightly different yields.
365x
How often daily-compounding accounts calculate interest
Daily compounding means the bank recalculates your interest every single day, slightly accelerating growth compared to monthly compounding.
$250,000
FDIC insurance limit per depositor, per bank
According to the Federal Deposit Insurance Corporation, deposits at insured banks are protected up to this limit per ownership category.
Rate Tiers, Variable Rates, and Other Terms to Know
Beyond APY and compounding, you may encounter a few other terms when shopping for or managing a savings account.
Rate Tiers
Some banks offer tiered interest rates, meaning the rate you earn depends on how much you keep in the account. A common structure might pay a lower rate on balances under $10,000 and a higher rate on balances above that threshold. Read the account disclosures carefully — sometimes only the portion above the threshold earns the higher rate, while other accounts apply the better rate to your entire balance once you qualify.
Variable vs. Fixed Rates
Almost every standard savings account carries a variable rate, which means the bank can raise or lower it at any time. This is normal, but it means the APY you see today is not guaranteed tomorrow. Certificates of deposit (CDs) are one common way to lock in a fixed rate for a set period, though they come with their own trade-offs around access to your money. For a deeper look at how savings accounts compare to other deposit options, see our comparison of savings and money market accounts.
Minimum Balance Requirements
Some accounts require you to maintain a minimum balance to earn the advertised APY or to avoid a monthly fee. Falling below that threshold could reduce your effective yield significantly.
This article is for general informational and educational purposes only and does not constitute personalized financial advice. Consult a qualified financial professional for guidance specific to your situation.
