Compound Interest Calculator

This compound interest calculator shows how a lump sum and regular deposits grow when interest is added on top of interest. Type a starting amount, how much you add each week, fortnight, month or year, the yearly rate and how long you will save. The final balance, the total you paid in and the total interest appear straight away and update as you type.

You choose how often interest is compounded: daily, monthly, quarterly, yearly or continuously. You can also say whether each deposit lands at the start or the end of the period, raise your deposit by a set percentage every year, and add inflation to see what the final balance would buy in today’s money. A chart and a year-by-year table show how the balance builds.

“Reach a goal” tells you how long it takes to hit a target with your current plan, and what deposit would get you there within your chosen number of years. The rule of 72 card shows roughly when your money doubles, next to the exact answer. Everything is worked out in your browser, so your numbers stay on your device.

1. Type your starting amount and, if needed, change the currency in the list beside it.
2. Add a regular deposit, choose how often you pay it, and whether it goes in at the start or end of each period.
3. Enter the yearly interest rate, the number of years and how often interest is compounded.
4. Optionally open “More options” to raise your deposit each year or allow for inflation.
5. Read the final balance, then explore the chart and the year-by-year table. Use Download CSV or Copy table to keep them.
6. Type a target in “Reach a goal” to see when you get there, and check the rule of 72 card for doubling time.

• Starting amount plus regular deposits weekly, fortnightly, monthly or yearly.
• Deposits at the start of each period (annuity due) or at the end (ordinary annuity).
• Daily, monthly, quarterly, yearly or continuous compounding, with the effective yearly rate (APY or AER) shown.
• Optional yearly rise in your deposit, for example 3% to keep pace with pay rises.
• Optional inflation adjustment that shows the final balance and every year in today’s money.
• Stacked bar chart of money paid in against interest, readable by hover, tap or arrow keys.
• Year-by-year table with CSV download and a copy button that pastes cleanly into Excel, Numbers or Google Sheets.
• Goal finder: time to reach a target, and the deposit needed to reach it in your chosen years.
• Rule of 72 estimate beside the exact doubling time, plus the rate needed to double in a set number of years.
• Thirty currencies, with yours picked from your browser’s language setting.

• Compare like with like. Banks often quote an effective yearly rate that already includes compounding, so check whether the rate you have is nominal or effective before typing it in.
• Paying in at the start of each period earns one extra period of interest on every deposit. Over decades that small change adds up to a noticeable sum.
• Use the inflation box to stay realistic. A balance that looks large in 30 years may buy far less, and the dashed line on the chart shows how much less.
• Tax on interest, account fees and changing rates are not included, so treat long-range results as a guide rather than a promise.