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Interest Rate Calculator
Solve for interest rate from principal, future value, and periods. Includes APR↔APY converter and effective annual rate.
Result
14.8698% per year
Formula: r = (FV/P)^(1/n) - 1
Rule of 72: At 14.87%, money doubles in ~4.8 years. (Rule of 72 estimate: 72 ÷ 14.87 = 4.8 years)
Formulas Used
- Simple Interest Rate: r = (FV - P) / (P × n)
- Compound Interest Rate: r = (FV/P)^(1/n) - 1
- Loan Rate: PV = PMT × [(1 - (1+r)^-n) / r] — solved via Newton-Raphson
- APR → APY: APY = (1 + APR/n)^n - 1
- APY → APR: APR = n × [(1 + APY)^(1/n) - 1]
- Rule of 72: Years to double ≈ 72 / rate(%)