Mortgage Refinance Calculator
Mortgage Refinance Calculator works out Current monthly payment and New monthly payment from Current loan balance, Current interest rate and Months left on the current loan. The default figures on this page give monthly saving of 308.14; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
6 steps
- Current payment = PMT on 250000 at 7.25% over 300 months = 1807.02
- New loan = 250000 payoff + 0 cash = 250000
- New payment = PMT on 250000 at 6% over 360 months = 1498.88
- Monthly saving = 1807.02 - 1498.88 = 308.14
- Break-even = 4500 of cash cost / 308.14 a month = 15 months
- Interest left on the current loan 292103.6 versus 289593.37 on the new one: a saving of 2510.23
Its 4 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
3 sources
Keep this result
Save it, change one figure, then compare the two
The calculation stays free. Save this scenario, adjust one assumption, save that too, and put them side by side to see exactly what the change costs you. A free account keeps 5 scenarios and 2 comparisons; Personal makes both unlimited and adds exports and private links. Nothing is saved unless you press Save.
What the Mortgage Refinance Calculator calculates
Compares the loan you have against the one you are being offered: new monthly payment, monthly saving, the months needed to recover the closing costs, and the lifetime interest difference, including cash-out and rolled-in costs.
How to use this Mortgage Refinance Calculator
Enter Current loan balance, Current interest rate, Months left on the current loan and New interest rate. Current monthly payment updates as you type. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Current monthly payment, New monthly payment and Monthly saving.
The method follows Board of Governors of the Federal Reserve System - A Consumer's Guide to Mortgage Refinancings, CFPB - Loan Estimate and Closing Disclosure (12 CFR 1026.37, 1026.38) and Standard annuity-immediate payment formula, PMT = P i / (1 - (1+i)^-n).
What you can compare
Change one input at a time to see how it affects Current monthly payment, New monthly payment and Monthly saving. The inputs you can vary are Current loan balance, Current interest rate, Months left on the current loan, New interest rate, New loan term and Closing costs.
Understanding Current monthly payment, New monthly payment and Monthly saving
An estimate from the figures you entered. A real offer depends on credit, appraised value, loan-level pricing adjustments and the lender's Loan Estimate, and refinancing resets the amortisation clock.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How much does it cost to refinance a $300,000 mortgage?
On the figures this page opens with — current loan balance 200,000, current interest rate 7%, new interest rate 5.5% and closing costs 4,000 — the monthly saving is 308.14. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
Is it worth it to refinance my mortgage calculator?
Compares the loan you have against the one you are being offered: new monthly payment, monthly saving, the months needed to recover the closing costs, and the lifetime interest difference. On the figures this page opens with — current loan balance 200,000, current interest rate 7% and new interest rate 5.5% — the monthly saving is 308.14. Put your own figures in their place and the working updates beside the result.
How to calculate a mortgage refinance?
Compares the loan you have against the one you are being offered: new monthly payment, monthly saving, the months needed to recover the closing costs, and the lifetime interest difference. Open “How this is worked out” beside the result to see each step for your own figures.
What information do I need for the Mortgage Refinance Calculator?
You need Current loan balance, Current interest rate, Months left on the current loan, New interest rate, New loan term, Closing costs, Discount points and Cash taken out. The page opens with default figures that give monthly saving of 308.14, so you can see the scale before entering your own.
What does this Mortgage Refinance Calculator show?
It shows Current monthly payment, New monthly payment, Monthly saving, New loan amount, Cost of discount points, Total up-front cost, Cash due at closing and Break-even point, with the working and any warnings for your entries.
Can I check how the Mortgage Refinance Calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.