Compound interest calculator

10,000 at 5% a year grows to 16,288.95 in 10 years when compounded yearly, or 16,470.09 when compounded monthly. You can add monthly or yearly contributions and enter your own interest rate.

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Please enter 0 if there is no initial deposit.

Please leave this blank or enter 0 if you make no regular contributions.

Contribution frequency
Contributions made at
%

Please enter the rate offered by your bank or investment product, or the annual return you expect. This tool does not suggest a rate.

Compounding
years

Result

Please complete the details. The result will appear here.

How it is calculated

  1. Rate per period i = (1 + annual rate ÷ m)^(m ÷ k) − 1, where m is the number of compounding periods a year (1, 4, 12 or 365) and k the number of contributions a year (12 or 1).
  2. Future value = initial deposit × (1 + annual rate ÷ m)^(m × years) + contribution × ((1 + i)^(k × years) − 1) ÷ i. For contributions at the start of each period, the contribution part is multiplied by (1 + i).
  3. Total interest = future value − initial deposit − total contributions.
  4. Effective annual rate = (1 + annual rate ÷ m)^m − 1.
  5. All values are calculated exactly and shown to two decimal places. Tax and charges are not included.
  6. All calculations are done in your browser. The details you enter are not sent to any server.

Worked examples

10,000 at 5% a year, compounded yearly for 10 years

Details
Initial deposit $10,000.00; 5% a year; compounded yearly; 10 years
Result
Future value $16,288.95; interest $6,288.95

10,000 at 5% a year, compounded monthly for 10 years

Details
Initial deposit $10,000.00; 5% a year; compounded monthly; 10 years
Result
Future value $16,470.09; interest $6,470.09

500 at the end of each month at 7% a year, compounded monthly for 30 years

Details
Initial deposit $0.00; monthly contribution $500.00 (end of period); 7% a year; compounded monthly; 30 years
Result
Future value $609,985.50; interest $429,985.50

1,000 plus 100 at the start of each month at 6% a year, compounded monthly for 20 years

Details
Initial deposit $1,000.00; monthly contribution $100.00 (start of period); 6% a year; compounded monthly; 20 years
Result
Future value $49,745.31; interest $24,745.31

5,000 at the start of each year at 8% a year, compounded yearly for 10 years

Details
Initial deposit $0.00; yearly contribution $5,000.00 (start of period); 8% a year; compounded yearly; 10 years
Result
Future value $78,227.44; interest $28,227.44