APY Calculator

What this calculates

The advertised rate on a savings account or CD (the APR, or nominal rate) isn't what you actually earn — how often interest compounds changes the real, effective annual yield. This tool converts a nominal annual rate into its true Annual Percentage Yield (APY) for a chosen compounding frequency, shows what that same rate would yield at every other standard frequency side by side, and optionally projects an initial deposit's growth over a chosen period.

How this tool works

1. Enter the nominal annual rate (APR) — the advertised, uncompounded rate.
2. Choose a compounding frequency — annually through daily, or continuous.
3. Optionally enter an initial deposit and investment period to project future value.
4. Choose a currency for the formatted output.

The Summary table shows your nominal rate, the chosen frequency, the resulting APY, and the gap between APY and APR — the extra yield compounding adds. APY by Compounding Frequency recalculates the same nominal rate at every standard frequency at once, so you can see exactly how much more often compounding is worth. Deposit Projection applies the calculated APY to your initial deposit over the investment period, showing the future value and total interest earned.

The math

APY is derived from the nominal rate r and the number of compounding periods per year n:

APY = (1 + r/n)^n − 1

Continuous compounding is the limit as n → ∞, computed directly as APY = e^r − 1. APY is always greater than or equal to APR — compounding more frequently can only add yield, never reduce it — so the gap between the two is always zero or positive. The deposit projection then compounds the initial deposit at the resulting APY for the given number of years: future value = deposit × (1 + APY)^years.

Common uses

• Comparing two savings accounts or CDs that advertise the same APR but compound on different schedules
• Checking a bank's advertised APY against the nominal rate they quoted
• Seeing how much difference monthly vs. daily compounding actually makes at a given rate
• Projecting what a deposit will actually be worth once the true yield is accounted for

To convert an APY back to a nominal rate, or run the full year-by-year growth schedule with recurring contributions, use the Compound Interest Calculator.

Privacy

This tool runs entirely in your browser. Your numbers are never uploaded to a server.