Calculator

Compound and Simple Interest Calculator

Work out simple or compound interest, see the total amount and a year-by-year table. Choose how often the interest is added.

Principal amount (₹)

Interest rate (% per year)

Time (years)

You can use a decimal, such as 2.5 for two and a half years.

Compounding

Principal

Interest earned

Total amount

Enter a principal, a rate (up to 100%) and a time of up to 100 years.

Balance at the end of each year
Year	Interest so far	Balance

An illustration of the maths, before tax. Banks and lenders may round differently or use their own day-count rules.

Interest Calculator quick facts

Simple interest:

Principal × rate × time ÷ 100

Compounding:

Yearly, half-yearly, quarterly, monthly or daily

Output:

Total amount, interest earned and a year-by-year table

Example:

₹1,00,000 at 8% for 3 years earns ₹24,000 simple interest

Tax:

Interest shown before tax

How to use the Interest Calculator

Choose compound or simple interest.
Enter the principal, the yearly rate and the time in years (decimals are allowed).
For compound interest, choose the compounding frequency, then read the interest, total and yearly table.

Simple versus compound

Simple interest is earned only on the original amount, so it grows in a straight line. Compound interest is earned on the amount plus the interest already added, so it grows faster over time.

Worked example

₹1,00,000 at 10% for 5 years earns ₹50,000 as simple interest. With yearly compounding it earns ₹61,051 and with monthly compounding about ₹64,531.

Common mistakes

Using a monthly rate as a yearly rate, entering months instead of years (use 0.5 for six months), and comparing deposits by stated rate without checking how often interest is compounded.

Frequently asked questions about the Interest Calculator

What is the formula for simple interest?

Simple interest equals principal × rate × time ÷ 100, where time is in years. For example, ₹1,00,000 at 8% a year for 3 years earns ₹24,000 in interest, so you receive ₹1,24,000 in total. The interest is always worked out on the original amount only.

What is the formula for compound interest?

Amount = principal × (1 + rate ÷ (100 × n)) ^ (n × time), where n is the number of times interest is added each year. Interest earned is the amount minus the principal.

How much does compounding frequency matter?

More frequent compounding earns slightly more, because interest is added to the balance more often. For example, ₹1,00,000 at 10% for 5 years becomes about ₹1,61,051 compounded yearly and about ₹1,64,531 compounded monthly. The effect grows with longer periods and higher rates.

How long will it take to double my money?

A quick estimate is the rule of 72: divide 72 by the yearly rate of return. At 8% it takes about 9 years with yearly compounding. It is a rule of thumb, so use the calculator's table for an exact figure at your own rate.

Is this the same as an FD or loan calculation?

It uses the standard formulas. Banks may use day counts, rounding or quarterly compounding, so use the FD and RD or EMI calculators for those products.

Is the interest taxed?

Interest is usually taxable as income, but the rules depend on where it is earned and your total income. This calculator shows interest before tax, so check how it will be taxed for your situation, or ask a tax professional.

Free, no sign-up. Reviewed 15 October 2026 by the Gopafy team. See all free tools.