Financial math you can inspect.

Our approach

We show the starting amount, total deposits, and projected interest separately, with a year-by-year table. The method page explains the formula, a small example you can reproduce, and the factors the model does not include.

The calculation was checked against independent high-precision examples and the Consumer Financial Protection Bureau's two-year example. Automated tests cover unusual rates, deposit schedules, invalid inputs, and keyboard use. These checks do not turn an estimate into a prediction or a financial recommendation.

What is available today

The compound interest calculator is the only published tool. It is designed for educational scenarios; it does not hold accounts, recommend investments, or collect the amounts you enter. See our privacy information for how the site handles data.