Skip to content
OneKitly
Sign up · Sign in

Interest Rate Calculator

Find the interest rate of a loan from its amount, term and monthly payment.

Related tools

All Savings & budgeting tools →
Nominal Interest Rate CalculatorWork back from an effective rate (APY/EAR) to the stated nominal rate.Compound interest calculatorSee how your money grows with compound interest and contributions.Simple interest calculatorCompute simple interest and the final amount from principal, rate and time.Percent Growth Rate CalculatorCompute the total change, simple annual growth and CAGR between two values.Savings rate calculatorCompute what share of your income you save each month.PVIFA Calculator (Present Value Interest Factor of an Annuity)PVIFA = [1 − (1+r)⁻ⁿ] / r — the number a payment is multiplied by to get a present value. Adjustable precision from 2 to 15 decimals, the ordinary and due factors together, an annuity-table row you can read across, and an explanation of why asking for more than 17 significant digits is meaningless in binary floating point.Forward Rate CalculatorDerive implied forward rates from a spot yield curve under annual, semi-annual or continuous compounding.Real Rate of Return CalculatorStrip inflation out of a nominal return with the exact Fisher equation, and see how far the simple subtraction is off.

Interest Rate Calculator works straight from this page — free, instant, nothing to install. You will find it under Savings & budgeting, with Nominal Interest Rate Calculator and Compound interest calculator for the neighbouring cases.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Interest Rate Calculator?

Find the interest rate of a loan from its amount, term and monthly payment.

When would I actually use this?

Planning a deposit, a safety net or a large purchase: how much to put aside each month, and how long a target takes at a given rate.

What is the most common mistake?

Reading a nominal rate as if it were real. Inflation is subtracted from the return, not from the capital, so a 3% account during 4% inflation loses purchasing power every year.

How is Interest Rate Calculator different from Nominal Interest Rate Calculator?

They sit next to each other but answer different questions: Nominal Interest Rate Calculator is the one to open when you need it to work back from an effective rate (APY/EAR) to the stated nominal rate. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

Compound interest calculator is the closest one after this: See how your money grows with compound interest and contributions.

What else is worth having open alongside it?

Simple interest calculator and Percent Growth Rate Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

Compound interest is arithmetic, so the maths is exact for the rate you enter. Real accounts vary in compounding frequency, tax treatment and whether interest is credited before or after a deposit.

Further reading

All guides →
ExplainerHow Does Compound Interest Work?Compound interest is interest earning interest. Here's the formula, a worked example, and why starting early beats saving more later.ComparisonSimple vs Compound Interest: What's the Difference?Simple interest grows in a straight line; compound interest snowballs. Here's how each works, a worked example, and which one you meet in real life.ExplainerWhat Is a Good Savings Rate? Benchmarks and Why It MattersYour savings rate decides how fast you reach financial independence. See how to calculate it, what benchmarks to aim for, and why it beats investment returns.How-toHow Long to Reach a Savings Goal: A Step-by-Step MethodWork out exactly how many months a savings goal will take from your monthly deposit, starting balance and interest rate — with worked examples.ComparisonAPR vs APY: What's the Difference?APR and APY both describe a yearly rate, but only APY includes compounding. Here's what each means and which one actually matters for savings and loans.ComparisonLife Assurance or a Pension Plan: the Lock-Up Decides, Not the Tax BreakScore both wrappers on the same rows and the pension plan wins the arithmetic at almost every horizon and almost every combination of tax rates — including when the rate does not fall at all. Which is exactly why the deduction is the wrong thing to decide on.