Compound Interest Calculator
See how money grows over time with compound interest. Choose your compounding frequency, add monthly contributions, and compare compound vs simple interest on a graph.
Growth Over Time
Parameters
Results
Step-by-Step Calculation
1. Compound interest formula
2. Substitute values
3. Calculate rate per period
4. Final amount (principal only)
5. Doubling time (Rule of 72)
Year-by-Year Breakdown
| Year | Balance | Interest Earned | Total Contributions |
|---|---|---|---|
| 1 | $2,279.05 | $79.05 | $2,200.00 |
| 2 | $3,623.53 | $144.49 | $3,400.00 |
| 3 | $5,036.81 | $213.27 | $4,600.00 |
| 4 | $6,522.38 | $285.58 | $5,800.00 |
| 5 | $8,083.97 | $361.58 | $7,000.00 |
| 6 | $9,725.44 | $441.48 | $8,200.00 |
| 7 | $11,450.90 | $525.46 | $9,400.00 |
| 8 | $13,264.64 | $613.74 | $10,600.00 |
| 9 | $15,171.17 | $706.53 | $11,800.00 |
| 10 | $17,175.24 | $804.07 | $13,000.00 |
Reference Guide
Compound Interest Formula
Compound interest earns interest on previous interest, causing exponential growth.
P is principal, r is annual rate, n is compounding frequency, and t is time in years.
Continuous Compounding
When compounding happens infinitely often, the formula uses the natural exponential.
Rule of 72
A quick estimate for how long it takes to double your money. Divide 72 by the annual interest rate.
Compound vs Simple
Simple interest grows linearly. Compound interest grows exponentially. The difference becomes dramatic over long time periods, which is why starting to save early matters so much.
