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Compound Interest Calculator

See how your money grows — or find the rate, time or starting amount you need to reach a goal.

Runs in your browser Free · no sign-up

At a glance

  • Compounds yearly, half-yearly, quarterly, monthly, weekly, daily or continuously — and compares all of them side by side for your numbers.
  • Add regular deposits monthly, quarterly or yearly, at the start or end of each period, and raise them every year.
  • Works backwards too: find the starting amount, interest rate or time needed to reach a target.
  • Shows the formula worked out with your numbers — A = P(1 + r/n)^(nt) — handy for homework and exams.
  • Gives the effective yearly rate (APY), how long your money takes to double, and how much more you earn than with simple interest.
  • A year-by-year chart and a monthly or yearly schedule you can download as CSV. Rupees, dollars, euros, pounds and dirhams.

Step by step

How to calculate compound interest

  1. 1

    Enter the starting amount

    The money you invest or deposit today (the principal).

  2. 2

    Set the rate and time

    The yearly interest rate and how many years (and months) it stays invested.

  3. 3

    Choose the compounding

    How often interest is added — quarterly for most Indian FDs, monthly or daily for many savings accounts.

  4. 4

    Add deposits if you like

    Turn on regular deposits to add money every month, quarter or year.

  5. 5

    Read the result

    The final amount, interest earned, effective rate, chart and schedule update as you type.

Features

Everything you need, nothing you don’t

Every compounding

Yearly to daily, plus continuous compounding.

Regular deposits

Monthly to yearly, start or end, with a yearly increase.

Solve for anything

Final amount, starting amount, rate or time.

Formula shown

Your values substituted into the formula.

Compare frequencies

See what daily vs quarterly compounding is worth.

Chart and schedule

Year by year or month by month, with CSV download.

The compound interest formula

A = P × (1 + r/n)^(n × t), where A is the final amount, P the principal, r the yearly rate as a decimal (8% = 0.08), n the number of times interest is compounded each year and t the time in years. The interest earned is A − P. For continuous compounding the formula becomes A = P × e^(r × t).

Example: ₹1,00,000 at 8% compounded quarterly for 5 years gives 1,00,000 × (1 + 0.08/4)^(4 × 5) = 1,00,000 × 1.02^20 = ₹1,48,594.74, so the interest is ₹48,594.74. With simple interest it would be only ₹40,000.

How much does the compounding frequency matter?

Compounding₹1 lakh at 8% for 10 yearsEffective rate
Yearly₹2,15,8928.000%
Half-yearly₹2,19,1128.160%
Quarterly₹2,20,8048.243%
Monthly₹2,21,9648.300%
Daily₹2,22,5358.328%
Continuously₹2,22,5548.329%

The rule of 72

Divide 72 by the yearly interest rate to estimate how many years it takes money to double: at 8% that is about 9 years, at 12% about 6 years. The calculator shows both this quick estimate and the exact doubling time for your compounding.

FAQ

Frequently asked questions

What is compound interest?

Interest earned on both your original money and the interest already added to it. Because the interest itself earns interest, the balance grows faster every year — unlike simple interest, which is paid only on the original amount.

How do I calculate compound interest?

Use A = P(1 + r/n)^(nt) and subtract P. For ₹50,000 at 7% compounded yearly for 3 years: 50,000 × 1.07³ = ₹61,252.15, so the interest is ₹11,252.15. The calculator shows these steps with your own numbers.

Is daily compounding better than monthly?

Yes, slightly. At 8%, daily compounding gives an effective rate of 8.328% against 8.300% for monthly — on ₹1 lakh over 10 years that is about ₹570 more. See the comparison table for your numbers.

How is an Indian bank FD compounded?

Most banks compound fixed deposit interest quarterly. For a detailed FD calculation with senior-citizen rates and TDS, use the FD calculator.

Can I find the rate I need to reach a target?

Yes. Choose Interest rate under Calculate, enter the amount you want, the starting amount and the time, and the calculator finds the yearly rate needed. It can also find the time or the starting amount.

What is the effective annual rate (APY)?

The rate you really earn in a year once compounding is counted. 12% compounded monthly is 12.68% a year effectively. It lets you compare offers with different compounding.

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