Compound Interest Calculator
See how your money grows with compound interest. Add monthly deposits with a yearly step-up, choose how often interest compounds, adjust for inflation, or work out what to invest to reach a goal.
- Instant results
- Goal planner
- Growth chart & table
- Nothing stored
Calculated on your device. Nothing is stored or uploaded.
Enter your numbers
Add a starting amount or regular deposit, a rate and a period to see your growth.
Growth over time
The growth chart appears here.
Compounding frequency
The same money and rate, compounded differently.
How to use the compound interest calculator
- Enter your moneyAdd a starting amount and, if you like, a regular deposit with how often you make it and a yearly increase.
- Set the rate and timeEnter the annual interest rate, how often it compounds and how many years and months to grow.
- Explore the resultsSee the final balance, chart and yearly table – or switch to Goal to find the deposit needed to reach a target.
How compound interest works
Each period, interest is calculated on the current balance – which already includes past interest – and then added to it. The more often this happens and the longer you leave the money, the faster it grows.
A = P × (1 + r/n)n×t
A = final amount, P = starting amount, r = annual rate (e.g. 0.08 for 8%), n = compounding periods per year, t = years.
Example: ₹1,00,000 at 8% compounded quarterly for 10 years = 1,00,000 × (1 + 0.08/4)40 ≈ ₹2,20,804.
Why time matters most
Starting earlier usually beats investing more later. ₹5,000 a month at 12% compounded monthly grows to about ₹50 lakh after 20 years, but to about ₹1.75 crore after 30 years – the last ten years add more than the first twenty because interest is earned on a much bigger balance.
Simple vs compound interest
| ₹1,00,000 at 10% a year | Simple interest | Compound (annual) |
|---|---|---|
| After 5 years | ₹1,50,000 | ₹1,61,051 |
| After 10 years | ₹2,00,000 | ₹2,59,374 |
| After 20 years | ₹3,00,000 | ₹6,72,750 |
Effective annual rate
When interest compounds more than once a year, the rate you actually earn is a little higher than the quoted one: EAR = (1 + r/n)n − 1. For 12% compounded monthly that is about 12.68%. Use the effective rate to compare products with different compounding.
Frequently asked questions
What is compound interest?
Compound interest is interest earned on your original money and on the interest it has already earned. Each period’s interest is added to the balance, so the next period’s interest is calculated on a larger amount – which is why growth speeds up over time.
What is the compound interest formula?
For a single deposit, A = P × (1 + r/n)^(n×t), where P is the starting amount, r the annual rate as a decimal, n the number of compounding periods per year and t the number of years. With regular deposits each deposit is compounded for the time it stays invested; this calculator adds them period by period.
Does compounding frequency make a big difference?
More frequent compounding earns slightly more, but the difference is usually small. At 12% a year, monthly compounding gives an effective rate of about 12.68% versus 12.36% for half-yearly. The comparison table shows the exact difference for your numbers.
What is the Rule of 72?
Divide 72 by the annual interest rate to estimate how many years it takes to double your money. At 8%, money roughly doubles in 9 years. The calculator shows both the Rule of 72 estimate and the exact doubling time.
What does “in today’s money” mean?
Prices rise over time, so a future amount buys less than the same amount today. Enter an inflation rate to see what your final balance would be worth in today’s purchasing power.
What is a step-up and why use it?
A step-up increases your regular deposit by a set percentage each year – for example 10% as your income grows. Even small yearly increases can raise the final balance a lot over long periods.
Should deposits be at the start or end of the period?
Deposits at the start of each period earn interest for one extra period, so they grow a little more. Many savings plans and SIPs debit early in the month; most loan-style formulas assume the end.
Does this include taxes and fees?
No. Results assume a constant rate with no tax, fees or charges. Interest on bank deposits and gains on investments are usually taxed, and market returns go up and down – treat the result as an estimate, not a promise.
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