Annuity Calculator

An annuity, in the mathematical sense, is just a series of equal payments made at regular intervals — a fixed contribution to a savings plan, a structured settlement, or level premiums building toward a payout. This calculator finds what that stream of payments grows to by the end, which is a different and easy-to-underestimate number from just multiplying the payment by the number of periods, since each payment compounds for whatever time remains after it's made.

This is the general building-block calculation behind a lot of retirement math: figuring out what regular payments into an annuity contract, a savings plan, or any fixed periodic investment will actually be worth once the interest earned along the way is accounted for, not just the raw total contributed.

The payment amount, rate and time period you're testing stay in your browser — no account, no data sent anywhere, just the math run locally on the numbers you're actually considering.

For an ordinary annuity, each payment is assumed to land at the end of its period, so the very last payment earns no interest at all while the first payment compounds for almost the full term. An annuity due assumes payments land at the start of each period instead, so every payment gets one extra period of compounding — which is why the annuity-due future value is always slightly higher for the same inputs.