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Free Compound Interest Calculator

Enter an amount, an interest rate and a time period to see how your money grows when interest earns interest. Choose how often it's compounded, add a regular monthly or yearly deposit if you like, and compare the result with simple interest.

  • 100% free
  • No sign-up
  • Instant results
  • Nothing leaves your device

Your money

What you start with, the interest rate and for how long.

The amount you start with.

% a year
years

Part years work too, e.g. 2.5.

Compounded

How often interest is added to the balance. Bank FDs are usually quarterly.

Regular deposits

Optional: add the same amount every month or year.

Add money

Results

Final balance

₹0

Enter the principal, rate and time period

Where the balance comes from
ItemAmount
Principal₹0
Interest earned₹0
Final balance₹0
What you put in vs interest
  • Principal₹0
  • Interest₹0

Compared with simple interest

At the same rate without compounding, you'd earn ₹0 in interest. Compounding adds ₹0 more, because interest earns interest.

  • Tax on the interest isn't included. The rate is an example: real rates can change over time.

Put it to work in a fixed deposit.

Try the FD calculator

Year by year

What you've put in, the interest earned so far and the balance at the end of each year.

Enter the principal (or a regular deposit), rate and time period to see the growth year by year.

How it works

  1. 1

    Enter the amount and rate

    What you start with, the yearly interest rate and how many years, including part years.

  2. 2

    Choose the compounding

    Yearly, half-yearly, quarterly, monthly or daily, and add a regular deposit if you want.

  3. 3

    See it grow

    The final balance, interest earned, the simple interest comparison and a year-by-year table.

Features

The compound interest formula

With compound interest, the interest you earn is added to your balance and then earns interest itself. The formula is A = P × (1 + r/n)^(n × t), where A is the final amount, P the principal, r the yearly rate ÷ 100, n how many times a year interest is compounded and t the number of years. The compound interest is A − P.

For example, ₹1 lakh at 8% a year compounded yearly grows to about ₹2,15,892 in 10 years, so you earn about ₹1,15,892 in interest. With simple interest, where interest is paid only on the original ₹1 lakh, you'd earn ₹80,000. Leave it for 20 years and it grows to about ₹4.66 lakh; for 30 years, just over ₹10 lakh. The longer the time, the bigger compounding's lead.

Regular deposits work the same way. The calculator adds each deposit at the end of its month or year, and from then on it grows at the same rate as the rest of your balance.

How often interest is compounded

The more often interest is compounded, the more you earn, because interest starts earning interest sooner. At 8% on ₹1 lakh for 10 years, yearly compounding gives about ₹2,15,892, quarterly about ₹2,20,804, monthly about ₹2,21,964 and daily about ₹2,22,535. The jump from yearly to quarterly is noticeable; beyond monthly, the extra is small.

In India, bank fixed deposits are usually compounded quarterly, recurring deposits quarterly too, and PPF interest is credited yearly. Our FD, RD and PPF calculators use the right method for each, so use them for those products, and this calculator for anything else.

The rule of 72

A quick way to estimate how long money takes to double: divide 72 by the yearly rate. At 8%, money doubles in about 9 years; at 6%, about 12 years; at 12%, about 6 years. It's an approximation, but a handy check on any result.

The same maths works against you on debt. A loan or credit card balance that's left to grow compounds in the same way, which is why paying off high-interest debt early often beats saving at a lower rate. The EMI calculator shows how much interest a loan really costs.

Frequently asked questions

How do I calculate compound interest?

Use A = P × (1 + r/n)^(n × t), then subtract P to get the interest. For ₹1 lakh at 8% compounded yearly for 10 years: 1,00,000 × 1.08^10 ≈ ₹2,15,892, so the interest is about ₹1,15,892.

What's the difference between simple and compound interest?

Simple interest is paid only on the original amount. Compound interest is also paid on the interest already earned. Over 10 years at 8%, ₹1 lakh earns ₹80,000 with simple interest and about ₹1,15,892 with yearly compounding.

Is monthly compounding better than yearly?

For savings, yes, slightly: interest is added 12 times a year instead of once, so it starts earning sooner. At 8% for 10 years on ₹1 lakh, monthly compounding earns about ₹6,000 more than yearly.

How are regular deposits treated?

Each deposit is added at the end of its month or year and then compounds at the same rate as the rest of the balance. Choose None to see the lump sum on its own.

How long does it take to double my money?

Roughly 72 ÷ the yearly rate, in years: about 9 years at 8% or 6 years at 12%. The year-by-year table shows exactly when your balance passes double.

Does this include tax?

No. Interest on most savings, such as FDs, is taxable, which reduces what you keep. The rate you enter is an example: check the actual rate and tax rules for your investment.

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