Compound Interest Calculator 📈
Watch your savings grow over time.
Your numbers
How to use this calculator
Enter your starting amount (zero is fine).
Add a monthly contribution if you'll add to it.
Pick an annual interest rate and number of years.
Choose a compounding frequency (monthly is most common).
See your future balance, contributions, and total interest.
Calculation method
Data source: Standard time-value-of-money mathematics.
Last data update: May 24, 2026
Worked examples
$1,000 · $200/mo · 7% · 30 yr
Interest dwarfs contributions over a long horizon.
$10,000 · $500/mo · 6% · 15 yr
$5,000 · $100/mo · 4% · 10 yr
Frequently asked questions
No. Results are pre-tax. In a Roth IRA, HSA, or 529 the impact for many users is small; in a taxable brokerage account the actual after-tax result is lower.
Interest gets added to your principal more often, so each subsequent compounding period earns interest on a slightly larger base.
No. Real returns vary. Use this tool to compare scenarios, not to predict.
This shows what a given plan grows to. The Savings Goal Calculator works backwards from a target to find the monthly amount you need.