Compound Interest Calculator
Convert an interest rate at one compounding frequency into its equivalent rate at another.
About this calculator
Convert an interest rate quoted at one compounding frequency into its equivalent rate at another — for example, turning a 6% Monthly (APR) rate into its equivalent Annually (APY) figure.
A rate compounded more frequently grows a balance faster than the same nominal rate compounded less often, so rates quoted at different compounding frequencies aren't directly comparable. This calculator converts any input rate to its effective annual rate (EAR) first, then converts that EAR into the equivalent rate at whatever output frequency you choose — the same method banks use to compare an APR (nominal, sub-annual compounding) against an APY (effective annual rate).
How to use
- Enter the input interest rate and select the compounding frequency it's quoted at.
- Select the compounding frequency you want to convert it to.
- Press Calculate to see the equivalent output interest rate.
Tips
- "Annually (APY)" is already an effective annual rate — every other frequency is treated as a nominal rate (APR) that compounds within the year.
Formula
Effective Annual Rate (EAR) = (1 + r/n)ⁿ − 1
Output Rate = n × [(1 + EAR)^(1/n) − 1]
where r = input rate, n = compounding periods per year (continuous compounding uses eʳ − 1 and ln(1+EAR) instead)