Compound interest calculator.

Interest earned on interest: each period's interest is added to the balance and earns interest itself from then on. For a lump sum the balance after t years is P(1 + r/n)^(nt), where r is the yearly rate and n the times it is compounded a year. Over long terms that is what makes the curve bend upward.

The rate you type is the nominal yearly rate; the APY (effective annual rate) is what it earns in a year once compounding is counted: (1 + r/n)^n − 1. 7% compounded monthly is 7.229% a year, and daily 7.250%. The APY is the fair way to compare two accounts.

Less than people expect. 10,000 at 7% for 20 years grows to 38,697 compounded yearly, 40,387 monthly and 40,547 daily. The rate, the time and the deposits matter far more than the compounding.

Each deposit lands on its own schedule, monthly or yearly. Between deposits the balance grows at the compounding's rate for that stretch, (1 + r/n)^(n/k) − 1, so any mix of compounding and deposits comes out exact. A deposit at the start of a period earns that period's interest; one at the end starts earning in the next.

Exactly, as ln 2 ÷ ln(1 + APY): at 7% compounded monthly that is 9.9 years. The rule of 72 (72 ÷ 7 = 10.3) is the mental shortcut for the same number. Deposits make it double sooner; the figure is for the starting balance alone.

Type the starting balance, the yearly rate and the years, pick how often it compounds, and add a monthly or yearly deposit if there is one. The balance, the deposits, the interest and the APY update as you type, with a chart and a table a year under them.

Yes. The CSV button downloads a row a year: the deposits and interest of that year, the balance at its end, and the running totals of deposits and interest, to the cent.

No. The figures are before tax, fees and inflation, at a rate that stays the same for the whole term. To see growth in today's money, take the inflation rate off the yearly rate as a rough guide.

No. The arithmetic runs in your browser and the page makes no request with your numbers.

No. The Compound interest calculator is free and opens without a sign-in, an account or an install.

The Compound interest calculator keeps nothing on a server; only the invoice generator saves its draft, in this browser's localStorage on your device. Nothing else is saved, and nothing is sent to shadcn.io.

annually, semiannually, quarterly, monthly, daily. Deposits are monthly or yearly, at the start or the end of each period, whatever the compounding.

From 1 to 100 whole years, at a yearly rate from 0% to 100%. The rate stays the same for the whole term.

A row a year: the deposits and the interest of that year, the balance at its end, and the running totals of deposits and interest, to the cent. The starting balance counts as a deposit in year 1.

Closest to the Compound interest calculator: Loan calculator, Percentage calculator, Currency converter, Discount calculator. Each opens on its own page, free and in the browser.

The Compound interest calculator is one of 20 in its group. The group's page, /tools/math, lists them all.

The tool is free. Its interface is built from shadcn.io's own components (Button, Input, Slider and the rest of the registry under /ui), which come in React, Vue, Svelte and Solid. Pro adds the blocks and templates for the product around it.