Savings
Convert nominal APR to annual percentage yield, convert APY back to nominal APR, or project growth from a quoted APY.
Effective APY
5.12%
Interest earned
$2,833.59
APY
5.12%
Nominal APR
5%
Future balance
$12,833.59
Result comparison
Bank disclosures can use product-specific rules. Confirm whether a quoted number is APY or nominal APR before comparing accounts.
Calculation method
The variable m is the number of compounding periods per year. For the reverse conversion, nominal APR equals m × ((1 + APY)^(1/m) − 1).
Detailed guide
APY measures the effective annual growth of a balance after compounding. A nominal APR states the periodic rate on an annual basis but does not include the extra return created when interest is added to the account during the year. This calculator converts in both directions so rates can be compared on the same basis.
The growth mode treats the entered rate as APY and applies it once per year on an equivalent basis. It does not add a second compounding effect. This distinction matters because applying monthly compounding to an APY would count compounding twice.
The variable m is the number of compounding periods per year. For the reverse conversion, nominal APR equals m × ((1 + APY)^(1/m) − 1).
Future value from APY is principal × (1 + APY)^years. The model assumes no deposits, withdrawals, fees or rate changes during the period.
Decision guide
Google competitors focus on the APY formula, compounding frequency, and why APY is useful. APY converts a nominal rate and its compounding schedule into a one-year effective yield, assuming interest stays in the account.
More frequent compounding can raise APY even when the nominal rate is unchanged. Once a provider gives a valid APY, it can usually be compared directly with another APY for the same kind of balance. Do not treat APY as a monthly rate.
Savings-account rates can change during the year. A calculation using one constant rate shows what would happen if that rate remained in place. Test a lower rate when planning future interest rather than treating today’s quote as guaranteed.
Tiered rates, minimum balances, promotional periods, and fees can reduce the yield actually earned. Compare the APY with the account terms and your expected balance pattern. Withdrawals also reduce the dollars available to compound.
Save a baseline, then change only one input at a time: amount, rate, term, or recurring payment. Record the supporting outputs as well as the headline result—contributions, interest, total cost, remaining balance, or target date. This isolates the assumption that actually changes the decision instead of hiding it inside several simultaneous edits.
Do not tune every assumption until the calculator produces a preferred answer. Start with a cautious case, follow with a central case, and treat the favorable case as an upside scenario. A calculator result is not a lender quote, market forecast, or tax determination; actual dates, rounding, fees, contract rules, and required payments must be checked in primary documents.
Keep enough precision in the inputs and round only the output used for a decision. If the estimate supports a transaction, loan, tax calculation, or long-term plan, repeat it with figures from the contract or official statement. Any difference helps identify the assumption that still needs verification.
APY includes the effect of compounding. Nominal APR needs a compounding frequency before it can be compared with APY.
More frequent compounding slightly increases APY when nominal APR is unchanged. The difference becomes larger at higher rates.
Minimum balances, tiered rates, fees and promotional periods can matter more than a small APY difference and are outside this formula.
Not always. APY is an effective annual yield that includes compounding. A stated interest rate may be nominal.
Select the conversion mode, enter nominal APR, and choose the number of compounding periods used by the account.
No. Use the compound-interest or savings-goal calculator when regular cash flows are part of the scenario.
Updated: August 1, 2026
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