Interest Rate Calculators
Understand how interest works on loans, savings, and investments. Our free calculators help you make informed financial decisions.
Simple Interest Calculator
Calculate interest without compounding
Compound Interest Calculator
See how your money grows with compound interest
APR Calculator
Calculate true annual cost of loans including fees
APY Calculator
Convert interest rates to annual percentage yield
Interest Rate Comparison
Compare two rates and see the difference
Understanding Interest Rates
Simple vs Compound Interest
Simple interest is calculated only on the principal amount, while compound interest is calculated on both the principal and accumulated interest. Compound interest makes your money grow faster over time.
APR vs APY
APR (Annual Percentage Rate) shows the yearly cost of borrowing without compounding. APY (Annual Percentage Yield) includes the effect of compounding, showing what you actually earn on deposits.
Quick Reference Formulas
Simple Interest
I = P × r × t Interest = Principal × Rate × Time
Compound Interest
A = P(1 + r/n)^(nt) Final Amount with compounding
APY Formula
APY = (1 + r/n)^n - 1 Annual Percentage Yield from APR
Rule of 72
Years to Double ≈ 72 / rate Quick doubling time estimate