Annuity Calculator

Written by Great Medico

Updated September 25, 2026 •3 min read

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A financial result is only as useful as the inputs behind it. Annuity Calculator calculates the future value of a stream of equal annuity payments using the payment amount, annual rate, term, payment frequency, and payment timing entered, so you can test the scenario with numbers that match your own situation.

What this calculator does

Annuity Calculator calculates the future value of a stream of equal annuity payments using the payment amount, annual rate, term, payment frequency, and payment timing entered. The visible form contains Payment timing, Annuity payment, Annual interest rate, Annuity term, Payment frequency. These are the inputs that define this calculator’s scope. If a value, rule, or adjustment is not represented by a working field, it should not be assumed to be included in the result.

How to use it

Enter Payment timing, Annuity payment, Annual interest rate, Annuity term and Payment frequency. Enter percentage or rate fields on the scale shown by the form rather than converting them to decimals yourself. Keep monetary inputs in the same currency, or use the currency selector when one is provided. Keep time and payment-frequency assumptions consistent with the labels on the page. Before calculating, recheck Payment timing and the other values that materially affect the result. For a clean comparison, hold the other inputs constant while changing one assumption at a time so you can see what is driving the result.

How the calculation works

For an ordinary annuity, future value = PMT × [((1+r)^n − 1)/r]. For an annuity due, the ordinary-annuity value is multiplied by (1+r) because each payment is made one period earlier. This is the calculation method that should anchor any manual check of the output. If a displayed field does not affect the current calculation, that limitation is stated below rather than silently treating the field as part of the formula.

Example

With the displayed example values (Payment timing = ordinary, Annuity payment = 1,000, Annual interest rate = 5, and Annuity term = 10) and the remaining defaults unchanged, the current calculator returns $155,282.28 for future value of annuity payments. Replacing those defaults with your own values recalculates the same relationship; change one input at a time if you want to see which assumption is driving the difference.

How to interpret the result

The result shows the modeled value at the end of the annuity term. Beginning-of-period payments produce a slightly higher value than otherwise identical end-of-period payments because each payment compounds for one extra period. Compare results produced from the same definitions and time period. A mathematically larger or smaller number is not automatically better unless the financial context makes that direction meaningful.

Limitations and notes

Actual annuity contracts can include surrender charges, mortality and expense fees, guarantees, riders, taxes, insurer crediting rules, and market-linked returns that are not represented by a fixed-rate formula. Where the calculator depends on estimates, rates, accounting classifications, or future behavior, test more than one plausible scenario before making a decision.