Material Insight
Difference Between APR and APY Interest Rates (2026)
By YKWiki Editorial Team · Published 2026-07-12
Two Interest Rate Measures, One Critical Compounding Difference
Annual Percentage Rate (APR) and Annual Percentage Yield (APY) are both annualized interest rate measures, but they calculate interest differently. APR reflects the simple annual interest rate without compounding — it tells you what you pay (or earn) in interest per year as a flat percentage. APY accounts for compound interest — it tells you the effective annual rate when interest is added to the principal periodically and itself earns interest. The more frequently interest compounds, the larger the gap between APR and APY.
The Math: Why Compounding Matters
Suppose you deposit $10,000 in a savings account with a 5.00% APR that compounds monthly. Each month, you earn 5.00% / 12 = 0.4167% interest. In the first month: $10,000 × 0.004167 = $41.67. In the second month: $10,041.67 × 0.004167 = $41.84. The interest earns interest. Over 12 months, the total is $511.62 — not $500. The APY is $511.62 / $10,000 = 5.116%. That 0.116% difference may seem small, but on $100,000 over 10 years, it equals $1,896 in additional earnings compared to simple interest.
APY formula: APY = (1 + APR/n)^n - 1, where n = number of compounding periods per year.
| Compounding Frequency | 5.00% APR Becomes | 10.00% APR Becomes | 20.00% APR Becomes |
|---|---|---|---|
| Annually (n=1) | 5.000% APY | 10.000% APY | 20.000% APY |
| Semi-annually (n=2) | 5.063% APY | 10.250% APY | 21.000% APY |
| Monthly (n=12) | 5.116% APY | 10.471% APY | 21.939% APY |
| Daily (n=365) | 5.127% APY | 10.516% APY | 22.132% APY |
| Continuously | 5.127% APY | 10.517% APY | 22.140% APY |
Side-by-Side Comparison
| Feature | APR | APY |
|---|---|---|
| Full Name | Annual Percentage Rate | Annual Percentage Yield |
| Accounts For Compounding | No | Yes |
| What It Measures | Simple annual interest cost/rate | Effective annual yield with compounding |
| Typically Used For | Loans, credit cards, mortgages | Savings accounts, CDs, investments |
| Always ≥ or ≤ APR? | APY ≥ APR (when compounding) | APY ≥ APR (when compounding) |
| Truth in Lending Act Disclosure | Required for consumer loans | Required for deposit accounts |
| Includes Fees? | Can include certain loan fees (mortgage APR) | No — pure interest rate measure |
Why Banks Use Different Measures for Different Products
This is not accidental. Banks advertise APY for savings products because the higher number looks more attractive — a 5.00% APR savings account becomes a 5.12% APY, and the bank prominently displays the larger number. Banks advertise APR for loan products because the lower number looks cheaper — a 20.00% APR credit card has an APY of 22.13%, but the card disclosure highlights the smaller APR. Both numbers are accurate; they just measure different things. The Truth in Lending Act (TILA) requires lenders to disclose APR for consumer loans and credit cards. The Truth in Savings Act requires banks to disclose APY for deposit accounts.
Real-World Examples in 2026
Credit Cards
A credit card with 24.99% APR compounding daily has an APY of 28.38%. If you carry a $5,000 balance for a full year, you pay not $1,249.50 (24.99% of $5,000) but $1,419 in interest — $169.50 more than the APR alone suggests. This is why credit card debt compounds so aggressively. Minimum payments cover interest plus a tiny fraction of principal, leaving most of the balance to accrue interest again next month.
Mortgages
A 30-year mortgage at 6.50% APR with monthly payments results in an APY of 6.697%. The APR disclosure for mortgages also includes certain fees (origination, points, mortgage insurance), making the mortgage APR slightly higher than the stated note rate. On a $400,000 mortgage, the difference between 6.50% APR and its effective APY translates to approximately $13,000 in additional interest over 30 years compared to simple interest calculation.
High-Yield Savings Accounts
An HYSAs offering 4.75% APY compounding daily has an APR of approximately 4.64%. The bank advertises the higher APY — and you earn the APY, not the APR. On a $50,000 deposit, you earn $2,375 in the first year (APY) not $2,320 (APR). The compounding bonus is $55 in year one and grows over time as the balance grows.
Practical Rules of Thumb
- When borrowing: Compare APRs between lenders. The APR is the best single number for comparing loan costs because it includes certain fees. But remember — the actual cost is slightly higher than the APR due to compounding.
- When saving: Compare APYs between banks. The APY tells you exactly what you will earn in one year on a given deposit. Higher APY = more money.
- Credit card debt: The APY is the true annual cost — and it is always higher than the stated APR. Use the APY when calculating how much interest you will actually pay.
- Quick sanity check: For monthly compounding, APY ≈ APR + (APR² / 12). At 5% APR: 5% + (0.0025/12) ≈ 5.12%. Close enough for most comparisons.
References & Standards
- ASTM International. Steel & Alloy Standards. astm.org
- International Organization for Standardization (ISO). iso.org
- National Institute of Standards and Technology (NIST). Materials Data. nist.gov
- ASM International. Materials Information Society. asminternational.org
- World Steel Association. Steel Statistical Yearbook. worldsteel.org