The method
How it is worked out
Solve Payment = P × i × (1+i)N ÷ ((1+i)N − 1) for i.
- P
- Principal
- Payment
- Monthly payment
- N
- Number of payments
- i
- Monthly interest rate
Interest Rate Calculator
Estimate the annual interest rate implied by a loan amount, repayment amount and term. The result updates as you type so you can compare scenarios quickly.
Keep in mind
What it leaves out
- FeesFees are not included.
- Nominal vs effectiveThe displayed annual rate is monthly rate × 12.
- Irregular schedulesIrregular payments need a cash-flow IRR calculation.
Use the calculator to compare scenarios rather than as a guaranteed forecast.
About the Interest Rate Calculator
Work backwards from a loan amount, monthly payment and number of instalments to estimate the rate built into the repayment schedule. Use it to sense-check a financing quote when the repayment is clear but the stated interest rate is missing or hard to compare.
How it works and an example to tryShow less
How to use the result
The tool solves the fixed-payment loan formula for a monthly interest rate and converts that to an annual figure. It assumes standard equal payments and a fully repaid balance at the end. An arrangement fee, insurance or final balloon amount would change the true borrowing cost and must be considered separately.
Example to try
Take a sofa or other fixed-payment purchase with 24 monthly instalments. Enter the financed amount and each payment, then compare the implied rate with the seller's quoted rate. If a deposit or fee is involved, adjust the financed amount before interpreting the answer.
Put it to work
Try it on a real situation
Load an example
What moves the result most
Worked out from your figures above. Tap a row to try it.
Who uses it, and when
Anyone offered instalment finance in a shop, buyers of furniture, phones or appliances on credit, and small businesses checking supplier finance that quotes a payment but not a rate.
Mistakes worth avoiding
- Forgetting to subtract the deposit from the price before entering the financed amount.
- Ignoring a final balloon payment, which makes the implied rate look lower than it is.
- Assuming zero-percent finance is free when the cash price would have been lower.
Questions
What does the Interest Rate Calculator do?
Estimate the annual interest rate implied by a loan amount, repayment amount and term.
How should I use the result?
The tool solves the fixed-payment loan formula for a monthly interest rate and converts that to an annual figure. It assumes standard equal payments and a fully repaid balance at the end. An arrangement fee, insurance or final balloon amount would change the true borrowing cost and must be considered separately.
Does TechBullion store the information I enter?
The core calculation or transformation runs in your browser. Normal website security and analytics may still record page-level events, but the tool does not need to create a public record from your inputs.
What mistakes do people make with an interest rate calculator?
Forgetting to subtract the deposit from the price before entering the financed amount. Ignoring a final balloon payment, which makes the implied rate look lower than it is. Assuming zero-percent finance is free when the cash price would have been lower.
Is the result guaranteed?
No. Use the result as a practical check or planning aid and verify important decisions with the relevant primary source, provider or professional advice.
Executive Insights
Leaders on this topic
Executive insightProgrammable Money Is the Next Banking Stack. Interview with Gleb Kurovskiy, LuminaryExecutive insightPaul Kukitz on Building Avoloan and Redefining the Future of Credit RefinancingExecutive insightHow Applied AI Is Reshaping Supply Chain: Javier Rodriguez Del Campo on Pricing, Procurement, and Decision-Making
Calculator results are estimates based on the figures entered and are not financial, investment, legal or tax advice.