Compound Interest Calculator

Estimate future value with compounding and optional contributions. Includes growth table and Show Work.

How to Use

  1. Enter your starting amount (principal).
  2. Set interest rate and compounding frequency.
  3. Add optional recurring contributions (monthly or yearly).
  4. Pick a term (years and optional extra months), then view results and “Show Work”.

Tip: This tool assumes a fixed rate (no variable-rate modeling). Contributions are applied on a consistent schedule.

Inputs & Settings
Enter values below. Results update instantly (no URL changes while typing).
Starting balance (today).
APR = nominal rate. APY includes compounding effects.
Continuous uses e^(r·t) (no discrete periods).
Example: 5 years + 6 months.
Set to 0 for none.
If “No contributions”, the contribution amount is ignored.
Summary
At-a-glance outputs (USD).
Principal
—
Rate
—
Term
—
Compounding
—
Results assume contributions are applied evenly per selected schedule and interest accrues according to the compounding option.
Show Work (step-by-step)
—
Work is shown using standard compound interest notation and consistent units.

Growth Table

Optional schedule view of balance growth over time.
Growth table showing period, starting balance, contributions, interest, and ending balance.
Period Start Contrib Interest End
Enter inputs to generate the table.
Use the checkboxes above to toggle monthly rows and rounding behavior.

Reference

Basic compound interest (no contributions)
FV = P × (1 + r/n)^(n·t)
Continuous compounding
FV = P × e^(r·t)
Common symbols
  • P = principal
  • r = annual rate (decimal)
  • n = compounds per year
  • t = time in years

This calculator provides estimates. Taxes, fees, minimums, and bank-specific rules are not included.

Tool Info

Last updated:

Updates may include additional schedules, edge-case handling, and output formatting improvements.