Compound interest calculator
Project the future value of your savings or investments with monthly contributions, see the total interest earned, a year-by-year growth table and a balance chart. Free, private, and calculated right in your browser.
Last updated: 18 June 2026
⚑ An estimate, not advice
This tool provides estimates for educational purposes only and is not financial, tax or legal advice. Returns are not guaranteed. Consult a licensed professional before making decisions.
$
$
Future value
$0
$0Starting principal
$0Total contributions
$0Interest earned
Year-by-year growth
| Year | Contributions to date | Balance |
|---|
Advertiser · affiliate
Put compounding to work — the halal way
Time in the market beats timing the market. If you want your wealth to grow without compromising your deen, start with Sharia-compliant funds and a steady monthly habit.
Best halal ETFs (US 2026) →How the compound interest calculator works
With monthly compounding, the future value of a starting principal plus a fixed monthly contribution is:
FV = P(1+r)n + C · [ (1+r)n − 1 ] / r
where P is your starting principal, C is the monthly contribution, r is the monthly interest rate (annual rate ÷ 12 ÷ 100) and n is the total number of months (years × 12). When the rate is zero, this simplifies to P + C × n.
Your total contributions are the starting principal plus every monthly deposit (P + C × n). The interest earned is simply the future value minus those contributions — the part your money made on its own. The longer your horizon, the more the curve above bends upward, because each year you earn interest on a larger balance, including last year's interest.
Frequently asked questions
How is compound interest calculated?
This tool compounds monthly: FV = P(1+r)ⁿ + C·[((1+r)ⁿ−1)/r], where P is the starting principal, C the monthly contribution, r the monthly rate (annual ÷ 12 ÷ 100) and n the number of months. With a zero rate it becomes P + C·n.
What's the difference between simple and compound interest?
Simple interest is earned only on your original principal. Compound interest is earned on your principal plus all previously earned interest, so it grows faster — and the longer the horizon, the bigger the gap.
How much does a monthly contribution change the result?
A lot. Each contribution compounds too, so regular monthly investing often makes up a large share of the final balance over long periods. Try changing the monthly amount to see the effect.
Is the return guaranteed?
No. This assumes a fixed annual rate for illustration. Real returns vary year to year and can be negative, and the result ignores inflation, taxes and fees. Treat it as an estimate, not a promise.
Related tools
Sources & further reading
Standard future-value-of-an-annuity and compound-interest formulas; U.S. Securities and Exchange Commission (investor.gov) compound interest guidance. Read our full disclaimer →