# Compound Interest Calculator

> Project savings growth with compound interest and regular contributions.

To calculate compound interest, enter your starting amount, any regular monthly contribution, the expected annual return and the number of years. The projection separates what you put in from what the interest earned, and shows the effective annual rate after compounding.

**URL:** https://convertto.tech/t/compound-interest-calculator
**Category:** Calculators (https://convertto.tech/c/calculators)
**Privacy:** Runs entirely in the browser; no upload
**Cost:** Free, no sign-up
**Last updated:** 2026-08-01

## Key facts

- **Privacy:** Runs entirely in your browser — nothing is uploaded
- **Cost:** Free, unlimited, no sign-up

## How to use

1. Set the initial amount.
2. Set the added each month.
3. Set the annual return.
4. Set the years.
5. Choose the compounding.
6. The result appears immediately — copy or download it.

## FAQ

### What is the rule of 72?

A shortcut for doubling time: divide 72 by the annual percentage return. At 7% a year, money roughly doubles every ten years. It is an approximation but accurate enough for mental arithmetic between about 4% and 12%.

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