# Compound interest calculator

See how money grows with compound interest

Use it at https://www.quicktoolz.com/tools/compound-interest-calculator. From QuickToolz.

Compound interest is interest earned on earlier interest as well as on your original money. ₹1,00,000 at 8% compounded yearly grows to about ₹2,15,892 in 10 years. Compounding more often gives slightly more, and regular additions usually make the biggest difference over a long time.

## How it works

A = P × (1 + r ÷ n)^(n × t)

In the formula, P is the starting amount, r is the yearly rate, n is the number of compounding periods a year and t is the number of years.

Monthly additions grow at the same rate from the month they are added.

Worked example: ₹1,00,000 at 8% compounded yearly for 10 years is 1,00,000 × 1.08¹⁰ = ₹2,15,892.50. The interest is ₹1,15,892.50.

## Examples

| Start | Rate | Time | Final amount |
| --- | --- | --- | --- |
| ₹10,000.00 | 6% | 5 years | ₹13,382.26 |
| ₹1,00,000.00 | 8% | 10 years | ₹2,15,892.50 |
| ₹1,00,000.00 | 8% | 20 years | ₹4,66,095.71 |
| ₹5,00,000.00 | 10% | 15 years | ₹20,88,624.08 |

## What this tool doesn't cover

- This assumes the same rate every year.
- Tax and fees aren’t included.
- This is an estimate, not financial advice.

## Questions

### What is the rule of 72?

Divide 72 by the yearly rate to estimate how many years money takes to double. At 8%, that is about 9 years.

### Does compounding frequency matter much?

A little. The rate and the time matter far more.

### What is the difference from simple interest?

Simple interest is paid only on the starting amount. Compound interest also earns on past interest.

### What is the compound interest formula?

A = P × (1 + r ÷ n)^(n × t). P is the starting amount, r is the yearly rate, n is compounds per year, and t is the years.

### Why does compound interest grow so fast over time?

Each period, you earn interest on past interest as well as on your original money. The effect is small at first and larger each year.

## Sources

- [Reserve Bank of India](https://www.rbi.org.in)
- [SEBI investor education](https://investor.sebi.gov.in)