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Financial · Tool

Compound Interest Calculator

See how your money grows over time with compound interest — enter principal, rate, compounding frequency, and optional contributions.

Initial investment
$
Annual rate
%
Period
yr
Monthly contribution
$
Compounding
Total contributions$0.00
Total interest$0.00
Total return0.00%
Future value
$ 0
...
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Industry use cases
Retirement Fund Growth Estimate how monthly 401(k) contributions compound over decades to plan a secure retirement date.
College Savings Fund Calculate how regular deposits to a 529 plan grow tax-free to cover future education costs.
Investment Portfolio Analysis Model long-term investment returns with dividend reinvestment to evaluate portfolio growth potential.
Mortgage Interest Breakdown Analyze how interest accrues over a loan term to understand total borrowing costs and prepayment savings.
Frequently asked questions
What is compound interest?
Compound interest is interest earned on both your initial investment and previously earned interest. This creates exponential growth where your money grows faster the longer you invest.
How often should compound interest be calculated?
Daily compounding grows money fastest, while annual compounding grows slowest. More frequent compounding means slightly higher returns, but the difference is small for low rates.
What's the difference between compound and simple interest?
Simple interest only applies to your principal amount. Compound interest applies to both the principal and accumulated interest, resulting in exponential rather than linear growth.
How do monthly contributions affect compound interest?
Monthly contributions earn compound interest themselves from the month they're deposited. Over time, these smaller regular deposits can significantly boost total returns through compounding.
How long does money take to double with compound interest?
At 7% annual compound interest, money approximately doubles in 10 years. The exact time depends on your interest rate and compounding frequency—use the calculator to find your specific timeline.
Related in Financial
APR Calculator → Salary Inflation Calculator → After-tax Cost of Debt → Effective Tax Rate Calculator →
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