Compound Interest Calculator

Calculate compound interest with monthly contributions and see your savings grow — free online.

About

About the Compound Interest Calculator

Calculates how a starting amount grows over time with compound interest and optional regular contributions, letting you choose how often interest compounds — monthly, quarterly, twice a year, yearly or daily.

Savers use it to see how much an account could grow by a future date, while anyone comparing savings products uses it to see how different rates or compounding schedules perform over the same term. It's one of many free calculators on Toolapt, and like every tool here, it's free to use with no sign-up and no limit on how many times you run it.

Choose what to view about this tool

Guide

Using the Compound Interest Calculator

  1. 1

    Step 1

    Enter your starting amount, annual interest rate and the number of years.

  2. 2

    Step 2

    Choose how often interest compounds, and how much (if anything) you add each period.

  3. 3

    Step 3

    Click "Calculate growth" to see the future value, total contributed and interest earned.

  4. 4

    Step 4

    Change any number and recalculate to compare different rates, terms or contribution amounts.

  • Supports five compounding frequencies — monthly, quarterly, twice a year, yearly and daily
  • Adds a regular contribution each compounding period, not just a one-time starting amount
  • Shows interest earned separately from what you actually contributed
  • Reports the effective rate per compounding period alongside the annual rate
  • Works entirely in your browser — no installs and no sign-up
  • Free to use, with no limit on how many times you run it
  • Fully responsive, so it works just as well on a phone as on a desktop

Savers

Savers use the Compound Interest Calculator for seeing how much a savings account or investment could grow by a future date.

Anyone planning regular contributions

Anyone planning regular contributions uses the Compound Interest Calculator for seeing how adding a fixed amount each period changes the final total.

Students learning personal finance

Students learning personal finance use the Compound Interest Calculator for seeing how compounding frequency changes the growth of the same rate.

Anyone comparing savings products

Anyone comparing savings products uses the Compound Interest Calculator for comparing how different rates or compounding schedules perform over the same term.

Examples

Compound Interest Calculator examples

3 worked examples

01

Lump sum, monthly compounding

Growing $5,000 at 6% compounded monthly for 10 years reaches $9,097.07, with $4,097.07 of that in interest earned.

02

Lump sum, yearly compounding

Growing $10,000 at 4% compounded yearly for 5 years reaches $12,166.53, with $2,166.53 in interest earned.

03

Monthly contributions, no starting balance

Adding $200 a month at 7% compounded monthly for 30 years reaches about $244,330, from $72,000 contributed and roughly $172,330 in interest.

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FAQ

Frequently asked questions

Quick answers to common questions about the Compound Interest Calculator.

What does the Compound Interest Calculator do?

It calculates the future value of a starting amount plus optional regular contributions, growing at a given annual rate with a chosen compounding frequency.

Is the Compound Interest Calculator free to use?

Yes. It's free, with no sign-up, no watermark and no limit on how many times you use it.

Is my input safe when I use this tool?

Yes. The numbers you enter are processed entirely on your own device — nothing is sent to a server.

When are contributions added?

Contributions are added at the end of each compounding period, before the next period's interest is calculated.

Does compounding frequency actually matter?

Yes — the same annual rate produces a slightly higher future value the more often it compounds, since interest starts earning its own interest sooner.

Does this account for inflation, fees or tax?

No. It shows the raw growth of the numbers you enter; inflation, account fees and tax on interest are not included.

Can I use the Compound Interest Calculator on my phone?

Yes. The page is fully responsive and works on mobile, tablet and desktop browsers alike.

Does the Compound Interest Calculator have any limitations?

It's built for everyday savings projections over terms up to 200 years, assuming a fixed rate for the whole period.

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