---
title: "Compound Interest Calculator with Monthly Contributions"
canonical: https://luckpanda.app/tools/compound-interest-calculator
language: en
updated: 2026-10-09
content: baseline
---

# Compound interest calculator

**Compound interest calculator: how it works** A = P × (1 + r ÷ n)^(n × t), where P is the starting amount, r the yearly rate as a decimal, n the number of times interest compounds a year and t the years. $10,000 at 8% compounded yearly for 10 years grows to $10,000 × 1.08^10 = $21,589.25.

Free online tool: https://luckpanda.app/tools/compound-interest-calculator (create on screen, no account needed).

## Compound interest, worked through

With yearly compounding, each year’s interest is added to the balance and earns interest the next year. $10,000 at 8%: year 1 ends at $10,800, year 2 at $11,664, year 3 at $12,597.12, and year 10 at $21,589.25. Of that, $11,589.25 is interest, more than the starting amount.

An Indian bank fixed deposit of ₹1,00,000 at 7% compounded quarterly for 5 years grows to ₹1,41,477.82, an effective rate of 7.186% a year.

| Compounding | Periods a year | $10,000 at 8% after 10 years | Effective annual rate |
| --- | --- | --- | --- |
| Yearly | 1 | $21,589.25 | 8.000% |
| Half-yearly | 2 | $21,911.23 | 8.160% |
| Quarterly | 4 | $22,080.40 | 8.243% |
| Monthly | 12 | $22,196.40 | 8.300% |
| Daily | 365 | $22,253.46 | 8.328% |

## How to use the compound interest calculator

1. Pick the currency and enter the starting amount.
2. Enter the yearly interest rate and the number of years.
3. Choose how often interest compounds, and add a monthly contribution if you have one.
4. Read the final amount and open the year-by-year table.

## Saving every month

Regular contributions usually matter more than the rate. $5,000 at 7% compounded monthly grows to about $20,194 in 20 years on its own. Adding $200 a month takes it to $124,379.03: $53,000 deposited and $71,379.03 of interest. Starting earlier matters most, because the first contributions compound the longest.

## Compound vs simple interest

Simple interest is paid on the starting amount only. Compound interest is paid on the growing balance. $10,000 at 8% for 20 years earns $16,000 of simple interest, but $36,609.57 compounded yearly. Use the simple interest calculator to compare.

## Questions people ask

### What is the compound interest formula?

A = P × (1 + r ÷ n)^(n × t), where P is the starting amount, r the yearly rate as a decimal, n the number of times interest compounds a year and t the years. $10,000 at 8% compounded yearly for 10 years grows to $10,000 × 1.08^10 = $21,589.25.

### Does compounding more often make a difference?

A little. $10,000 at 8% for 10 years reaches $21,589.25 compounded yearly, $22,080.40 quarterly, $22,196.40 monthly and $22,253.46 daily. The effective annual rate rises from 8% to 8.243% quarterly and 8.300% monthly.

### How are monthly contributions handled?

Each contribution is added at the end of the month and then earns interest at the same effective rate as the balance. $5,000 plus $200 a month at 7% compounded monthly grows to $124,379.03 after 20 years, of which $71,379.03 is interest.

### What is the rule of 72?

A quick estimate of how long money takes to double: divide 72 by the yearly rate. At 8% that is about 9 years (the exact figure, compounded yearly, is 9.01 years).

### What is the effective annual rate?

What a nominal rate earns in a year once compounding is counted: (1 + r ÷ n)^n − 1. Banks call it the annual equivalent rate (AER) in the UK and the annual percentage yield (APY) in the US.

### Is interest on savings taxed?

Usually, yes, but the rules depend on your country and the account. This calculator shows growth before tax; your bank or tax adviser can say what is taxable.