Calculators
Compound Interest Calculator
Estimate final balance, contributions, and interest earned with compounding.
Interest earned: 23,367.82 before taxes, fees, inflation, or rate changes.
Starting principal
10,000
Principal growth
20,096.61
Total contributions
30,000
Contribution growth
43,271.2
Interest earned
23,367.82
Interest share
36.88% of final balance
Contribution share
47.34% of final balance
Principal share
15.78% of final balance
Compounding periods used
120 (Monthly)
About This Tool
Estimate how a balance grows when interest is added back into the principal over time. Add optional annual, monthly, biweekly, or weekly contributions to model a regular savings plan.
How To Use It
- Enter the starting principal.
- Enter the annual interest rate and time in years.
- Choose the compounding frequency.
- Optionally add a recurring annual, monthly, biweekly, or weekly contribution and whether deposits happen at the beginning or end of each contribution period.
Examples
Monthly compounding
10,000 at 7% for 10 years with monthly compounding grows to about 20,097 before any extra contributions.
Monthly savings plan
Adding 250 per month at the end of each period raises the same 10-year estimate to about 63,368.
Useful Notes
Formula
The starting principal uses A = P(1 + r/n)^(nt), where n is the number of compounding periods per year.
Contribution timing
Beginning-of-period contributions grow for one extra contribution interval compared with end-of-period contributions.
Assumptions
Results assume the annual rate stays constant and that contributions are made on schedule. Taxes, account fees, inflation, market volatility, and withdrawal rules are not included.
FAQ
Does this include regular deposits?
Yes. You can include annual, monthly, biweekly, or weekly contributions and choose whether each contribution is made at the beginning or end of its period.
Does this account for taxes or fees?
No. The estimate uses the rate you enter and does not subtract taxes, account fees, inflation, or changing rates.
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