Project how a principal grows with monthly compounding and an optional monthly deposit.
| Future value | – |
| Total contributions | – |
| Total interest | – |
Use this compound-interest calculator for a savings account, CD, or investing habit where interest stays invested. Optional monthly contributions are added at the end of each month (ordinary annuity).
Interest is applied monthly at annual rate ÷ 12. Future value of the principal is P × (1 + r/12)^(12 × years). Future value of the deposits is PMT × ((1 + r/12)^(12 × years) − 1) / (r/12), or PMT × months if the rate is zero. Total contributions are principal plus all monthly deposits. Interest earned is future value minus total contributions. Years are whole years.
Principal: What you start with, before monthly deposits.
Annual rate (%): Yearly interest as a percent, e.g. 4 for 4%.
Years: How long the money stays invested, in whole years.
Monthly contribution: Extra you add each month. Use 0 if you will not add more.
Future value: Principal and deposits grown together.
Total contributions: Everything you put in.
Total interest: Future value minus contributions.
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