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financial / Free Online Tool

Interest Rate Calculator.

Find the effective interest rate of a loan or investment based on payment structures.

Input Parameters

$
$
months

Comments & Feedback.

Documentation

User manual & function guide.

Detailed manual explaining every function, input parameter, and operational example for the Interest Rate Calculator.

Loan Principal

Function

Total borrowed loan principal.

Example Operation Principal = $10,000

Monthly Payment

Function

Regular monthly payment amount.

Example Operation Payment = $210

Term Duration

Function

Total loan term in months.

Example Operation Term = 60 months

Effective APR

Function

Solves for actual annual percentage rate using Newton-Raphson method.

Example Operation $10,000 loan with $210/mo for 60 mos -> 9.88% APR (10.34% APY)

Frequently asked questions.

What is the difference between APR and effective interest rate?

APR (Annual Percentage Rate) is the simple annual rate, while the effective interest rate accounts for compounding. The effective rate is always equal to or higher than the APR.

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