Compound Interest Calculator — Free Investment Growth Tool
Free compound interest calculator — see how much your money can grow with compound returns. Calculate APY, investment growth & savings projections instantly.
Last Updated: March 25, 2026
Instant Results
$20,096.61
Future Value
$10,096.61
Interest Earned
$10,000
Principal
How to Use
- Enter your starting principal (the lump sum you're investing today).
- Set the expected annual interest rate (7% is a long-run S&P 500 nominal benchmark; 4–5% is conservative for high-yield savings).
- Choose the time horizon in years.
- Set compounding frequency (12 for monthly, 365 for daily, 1 for annually). Read future value and total interest instantly.
Formula Explained
A = P × (1 + r/n)^(n × t)
- A
- = Future value — what your money grows to
- P
- = Principal — your starting amount
- r
- = Annual interest rate as a decimal (7% = 0.07)
- n
- = Number of times interest compounds per year
- t
- = Time in years
Worked example: $10,000 at 7% compounded monthly for 10 years: A = $10,000 × (1 + 0.07/12)^(12 × 10) = $20,096.61. Total interest: $10,096.61.