Compound Interest Calculator

Calculate the future value of your investments with compound interest. Compare different compounding frequencies and contribution schedules.

Calculator Inputs
Initial Investment Principal
$10,000
Annual Interest Rate APR
6%
Investment Length Years
10 years
Compounding Frequency
Tax Rate Annual
0%
Inflation Rate Annual
2.5%
Monthly Contribution Regular
$100
Contribution Frequency
Contribution Increase Annual
0%
Results
Future Value
$17,908.48
After 10 years at 6% APR
Total Interest
$7,908.48
Effective Rate
6.14%
Inflation Adjusted
$13,864.22
Total Contributions
$10,000
Compounding Frequency Analysis
Annual
Semi-Annual
Quarterly
Monthly
Daily
Continuous
Understanding Compound Interest

What is Compound Interest?

Compound interest is interest earned on both the principal amount and the accumulated interest from previous periods.

A = P(1 + r/n)^(nt)

Where: A = future value, P = principal, r = annual rate, n = compounding periods per year, t = years

The Power of Compounding

Starting early gives you a significant advantage due to the exponential nature of compound interest.

$200/month for 10 years (25-35)
vs $200/month for 30 years (35-65)

The early starter wins despite investing 1/3 the amount!

Rule of 72

A quick way to estimate how long it takes for an investment to double:

Years to Double = 72 ÷ Interest Rate

At 8%: 9 years. At 6%: 12 years. At 10%: 7.2 years.

Continuous Compounding

The theoretical limit of compounding frequency:

A = Pe^(rt)

Where e ≈ 2.71828 (Euler's number)

Frequency Comparison
Compounding Frequency Future Value Effective Rate Total Interest