About the Compound Interest Calculator
The compound interest calculator shows how savings grow when the interest earns interest too. Enter a starting amount, a regular deposit, the yearly rate and the term, and see the final balance, how much of it you paid in and how much is interest.
Choose whether you deposit every month or every year, at the start or at the end of each period, and how often the interest is added: yearly, every six months, quarterly, monthly or daily. The effective annual rate shows what a rate compounded more often is worth over a whole year.
The year-by-year table lists what you paid in, the interest earned, the total interest and the balance at the end of every year, and you can download it as a CSV file for a spreadsheet. Everything is calculated in your browser; nothing you type is sent anywhere.
How to use it
- Enter a starting amount, a regular deposit or both, and choose the currency.
- Choose whether the deposit is paid every month or every year, and at the start or at the end of the period.
- Enter the yearly interest rate and choose how often interest is compounded.
- Enter the term in years or months, up to 100 years.
- Read the final balance, then open the yearly table or download it as a CSV file.
Features
- Deposits and a starting amount: Combine a lump sum with monthly or yearly deposits, paid at the start or at the end of each period.
- Any compounding: Yearly, every six months, quarterly, monthly or daily, with the effective annual rate it gives.
- Year-by-year table: See the deposits, interest and balance of every year, with a short last year shown in months.
- Spreadsheet download: Download the table as a CSV file with plain numbers, ready for Excel, Numbers or Google Sheets.
- Your currency: Amounts are shown in won, yen, dollars, euros, pounds or reais, in your language’s number style.
Examples
Monthly savings
Put away 100,000 won a month for 10 years at 3.5% compounded monthly and see how much of the result is interest.
A lump sum
Leave 10,000 dollars for 20 years at 5% compounded yearly to see it grow to about 26,533 dollars.
Comparing offers
Compare 4% compounded monthly with 4.1% compounded yearly by their effective annual rates.
Limitations and notes
- This is an estimate. It assumes money paid in between two compounding dates earns the same effective rate; banks often count simple interest for that part, so the result can differ by a few units.
- Taxes on interest, fees and inflation are not included.
- The rate and the deposit stay the same for the whole term.
- Amounts up to 1 trillion, rates up to 100% and terms up to 100 years are accepted.
Frequently asked questions
What is compound interest?
Interest that is added to the balance and then earns interest itself. Over many years this makes the balance grow faster and faster.
Does it matter when I deposit?
Yes. A deposit at the start of a month or year earns interest for that period; one at the end starts earning only after it, so the result is a little smaller.
What is the effective annual rate?
The yearly growth after compounding: 5% compounded monthly is worth about 5.12% a year. It lets you compare rates with different compounding.
Why is my bank’s figure slightly different?
Banks may round each interest payment, count interest by the day or treat money paid in between two compounding dates differently. The calculator does not round along the way.
Is my data sent anywhere?
No. The calculation runs in your browser and nothing is uploaded or stored.