Compound Interest Calculator

A savings balance grows faster when interest is added to the principal and then earns interest itself. Compound Interest Calculator projects that balance.

The inputs that change the result

You enter principal, annual interest percent, years, how many times a year interest compounds, and an optional contribution each period. Compounding can be annual, twice a year, quarterly, monthly, or daily (1, 2, 4, 12, or 365). The rate per period is the annual rate divided by that count. Future value is principal times (1 + rate per period) raised to the number of periods. A contribution is treated as an ordinary annuity: deposited at the end of each period, not at the start. At a zero rate the future value is principal plus contribution times the number of periods. The page also shows total contributed, interest earned, and the period count.

Contribution means per period, not per month

If you select annual compounding, the contribution is once a year. If you select monthly, it is once a month. There is no separate “monthly deposit” field that stays monthly while compounding stays annual. Taxes, fees, and market losses are ignored, and the result says the figure is an estimate. Simple Interest Calculator does not credit interest on interest. Mortgage Calculator and EMI Calculator amortize a debt. Loan Calculator is for a payment you owe, not a balance you are growing. Rule-of-72 style shortcuts are not used here; the page uses the compound formula.

What this tool will not do

It will not inflate the result, apply a tax rate, or vary the rate year by year. Principal and contribution cannot be negative. Years must be greater than zero. You cannot pick weekly compounding. The numbers stay in this browser. If you need a loan payment instead of a future savings balance, switch to EMI Calculator or Mortgage Calculator rather than forcing this form to answer that question.