NumSmith

Compound interest calculator

How an initial amount plus monthly contributions grows with compounding.

…

Share

For reference only

Results use standard formulas and published rates. Actual figures may differ due to personal deductions, institution rules and rounding. Do not rely on this alone for legal or financial decisions.

When to use this

Project a savings or investment balance year by year. The table shows contributions, interest and balance for each year, making it obvious when compounding starts to dominate.

How to use it

  1. Enter the starting amount, monthly contribution, annual return and years.
  2. Pick the compounding frequency.
  3. Read the final balance and the yearly table.

Frequently asked questions

What is the rule of 72?
Divide 72 by the annual return to estimate the years to double. At 6% that is about 12 years.

When people use this

Related calculators