MONEY & BUSINESS / SAVING & INVESTING

Compound interest

See how an initial balance and regular monthly deposits might grow over time.

← All tools

Your numbers

Loading calculator...

◈ Your values stay in your browser. No account needed.
YOUR RESULT

Enter your numbers to see a result.

WORKED EXAMPLE

Compound interest: a worked example

With starting balance 10,000, deposit each month 250, annual interest rate (%) 5, years 10, the projected balance is $55,290.66.

Inputs
Starting balance10,000
Deposit each month250
Annual interest rate (%)5
Years10
Results
Projected balance$55,290.66
Amount deposited$40,000.00
Interest earned$15,290.66

Amounts are shown in US dollars for illustration. Choose your own currency in the calculator above; it labels amounts and does not convert them.

THE METHOD

How it works

This projection assumes a constant nominal annual rate, monthly interest crediting and deposits made at each month end. It ignores inflation, fees and taxes.

FormulaMonthly balance = previous balance × (1 + annual rate/12) + monthly deposit.
WHY IT MATTERS

Make the numbers useful

Try changing one input at a time. The live result helps you see which assumption has the greatest effect.

Use Save scenario A, change an input, and compare both results side-by-side. You can also share your settings using a link.

Modelled results are estimates. Independently check decisions involving health, finances or safety.
QUESTIONS

Frequently asked questions

How is the compound interest calculated?

Monthly balance = previous balance × (1 + annual rate/12) + monthly deposit. This projection assumes a constant nominal annual rate, monthly interest crediting and deposits made at each month end. It ignores inflation, fees and taxes.

What does the compound interest example show?

With starting balance 10,000, deposit each month 250, annual interest rate (%) 5, years 10, the projected balance is $55,290.66. Amount deposited: $40,000.00; Interest earned: $15,290.66.

What assumptions and limits apply?

This is an estimate based on the inputs and assumptions shown on this page, not professional advice. Check anything with financial, health or safety consequences independently.

Is my data private?

Yes. Calculations run in your browser and your numbers are not sent to a server. A share link contains the inputs you choose to share, so check it before sending it to anyone.

Can I use my own currency?

Yes. Pick from 33 currencies and the amounts are labelled to match. The selector does not convert between currencies, so enter prices in your own currency.

FOR WEBSITE OWNERS

Embed this calculator on your site

Free to use. Paste this where you want the calculator to appear. It resizes itself and links back to Calculator786. Optional: add data-currency="EUR" to the div to preset a currency.