Finance
Compound interest calculator
Compound interest is the engine behind both savings growth and debt growth, and small changes in rate or time swing the result surprisingly hard. Enter a starting principal, rate, compounding frequency, and optional monthly deposits to see the final balance, total interest earned, and the effective annual rate your nominal rate really delivers. Use it to compare savings accounts, project a certificate of deposit, or understand what a credit card balance does when left alone.
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Compound Interest Calculator
Watch principal, interest, and compounding frequency grow a balance over time.
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Savings and investment journalRecord starting balances and contribution assumptions for future comparisons.Paid link · Check current price ↗As an Amazon Associate I earn from qualifying purchases.The math, plainly
How it works
- 01
The principal grows at rate ÷ frequency, compounded once per period for all periods.
- 02
Monthly deposits are converted to the compounding period and earn the same rate — an approximation when deposits and compounding don't align exactly.
- 03
The effective annual rate shows what your nominal rate is really worth once compounding frequency is applied.
Try a real scenario
$5,000 at 5%
InputsCompounded monthly, 10 years, $100/month added
ResultAbout $23,763 final balance, with $6,763 of it interest.
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More options for this calculator
Compound interest workbook (paid link)
Work through contribution and compounding scenarios on paper.
Financial calculator (paid link)
Check interest and contribution calculations with a handheld tool.
Savings goal chart (paid link)
Track deposits and milestones alongside the estimate.
As an Amazon Associate I earn from qualifying purchases.