WerklyTools
Esc
↑↓ navigate↵ open
EN
Buy me a coffee

Compound interest calculator

Simulate how your savings or investment grows: initial amount, monthly contribution, interest rate, years and compounding frequency. You will see the final balance, what you paid in and the interest earned.

Processed 100% in your browser

How can I verify this?

Your files are never uploaded: they are processed on your device. Check it yourself: load the page, turn off your WiFi and the tool keeps working. Or open your browser’s developer tools (F12), go to the Network tab, and see that no file leaves your device.

—Final balance
—Total contributed
—Interest earned

Year by year

Ctrl + Enter runCtrl + C copy result

How to use

  1. 1Enter the initial amount and the monthly contribution.
  2. 2Set the annual interest rate and the number of years.
  3. 3Choose how often interest is compounded.
  4. 4Review the result and the year-by-year table.

Use cases

  • Estimate what you will have at retirement with monthly savings.
  • Compare the effect of different interest rates.
  • Plan an emergency fund or a home down payment.
  • See how much time matters for an investment.

Frequently asked questions

What is compound interest?

Interest calculated on the principal plus the interest already accumulated, so money grows faster and faster over time.

When are contributions made?

At the end of each month. Interest is compounded at the frequency you choose.

Does this guarantee a real return?

No. It is a simulation at a constant rate. Real investments vary, and it ignores taxes, fees and inflation. It is not financial advice.

Is my data stored?

It is not sent to any server. Calculations run in your browser.

Related tools

Age calculatorEnter your date of birth and find your exact age, how many days and hours you have lived and how long until your next birthday. You can also calculate how old someone was or will be on any other date.
BMI calculatorEnter your weight and height to get your BMI instantly, its World Health Organization classification and the healthy weight range for your height. Works with metric and imperial units.
Online timer and countdownSet the duration you need, or pick a date and time, and the timer counts down on a large, easy-to-read clock. When it reaches zero an alarm sounds and the display flashes. It suits cooking, studying, presenting or waiting for an event.
Date calculatorTwo calculators in one: find out how many days, weeks, months or years lie between two dates (with business days shown separately), or start from a date and add or subtract any amount of time to learn which day you land on. It handles leap years and sends nothing to a server.
Discount calculatorFind out how much you will pay after a markdown, what percentage you were actually given, how two successive discounts add up or what the price was before the sale. Enter the amounts and see the final price and your savings instantly.
PDF invoice generatorFill in your details and your client’s, add the line items and download a clean PDF invoice with the totals calculated: subtotal, discount, VAT and withholding. Your details are kept only in your browser so you do not retype them, and numbering advances by itself. There is no sign-up and no server involved.