Compound Interest Calculator
Project how your savings grow with compound interest and regular contributions.
$
$
Future value
$125,510.22
Total contributions
$58,000.00
Total interest earned
$67,510.22
How to use
- Enter your initial investment and optional monthly contribution.
- Set the number of years and expected annual return.
- Choose how often interest compounds.
- See your future value, total contributions, and interest earned.
Formula
Future value with contributions: FV = P(1 + r/n)^(nt) + PMT × [((1 + r/n)^(nt) − 1) / (r/n)], where P is principal, r is annual rate, n is compounding frequency, t is years, PMT is contribution per period.
Example
$10,000 initial investment, $200/month for 20 years at 6% compounded monthly:
Future value ≈ $118,000+ (contributions $58,000, interest earned ≈ $60,000).
Frequently asked questions
What is compound interest?
Compound interest is interest calculated on both the initial principal and accumulated interest from previous periods. It makes your money grow faster over time.
How does compounding frequency affect returns?
More frequent compounding (e.g., monthly vs. annually) yields slightly higher returns at the same annual rate.
Are the returns guaranteed?
No. This calculator uses a fixed rate for projection. Actual investment returns vary with market conditions.
Can I model retirement savings?
Yes. Use the retirement calculator for a more detailed projection including withdrawal estimates.
What is compound interest vs simple interest?
Compound interest earns interest on both principal and accumulated interest. Simple interest is calculated on principal only.
How much will $10,000 grow in 10 years?
At 7% compounded monthly with no contributions, $10,000 grows to about $20,096 in 10 years. Use this calculator with your exact rate and contributions.