Compound Interest Calculator
Convert interest rates between compounding frequencies and calculate future value with compound growth formulas.
Interest Rate Converter
Convert an annual rate from one compounding frequency to an equivalent rate at another frequency.
Compound Growth Calculator
Calculate future value of a principal invested at a given rate and compounding frequency.
Formulas
A = P(1 + r/n)nt
APY = (1 + r/n)n − 1
APY = (1 + r/n)n − 1
How to use this compound interest calculator
- Rate converter: Enter a nominal rate and select input/output compounding frequencies to find the equivalent rate.
- Growth calculator: Enter principal, annual rate, years, and compounding to see future value and interest earned.
Compound interest formulas
A = P(1 + r/n)nt
APY = (1 + APR/n)n − 1
Where P is principal, r is annual rate (decimal), n is compounding periods per year, and t is years.
Example: $10,000 at 5% compounded monthly for 10 years grows to about $16,470.
Real-world uses
- Savings accounts: Compare APY quoted daily vs monthly compounding.
- Investments: Project long-term growth of retirement or brokerage accounts.
- Loans: Understand how compounding frequency affects effective borrowing cost.
Frequently Asked Questions
Interest calculated on both the initial principal and accumulated interest from previous periods — interest earns interest.
APR is the nominal annual rate. APY (effective annual yield) accounts for compounding frequency and is always equal to or higher than APR for the same rate.
Yes. More frequent compounding yields slightly higher effective returns at the same nominal rate. Daily compounding beats annual compounding.