Mortgage Refinance Calculator

Written by Great Medico

Updated September 25, 2026 •3 min read

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Small changes in rates, timing, or amounts can materially change a finance result. Mortgage Refinance Calculator compares the current mortgage with a proposed refinance using balance, old and new rates and terms, closing costs, and any cash-out amount entered, which makes the assumptions easier to test side by side.

What this calculator does

Mortgage Refinance Calculator compares the current mortgage with a proposed refinance using balance, old and new rates and terms, closing costs, and any cash-out amount entered. The visible inputs are current loan balance, current annual rate, remaining term on current loan, new annual rate, new loan term, refinance closing costs, and cash-out amount. Its result is driven by those values, so the calculation can be reproduced or stress-tested without relying on a hidden live-data feed.

How to use it

Enter Current loan balance, Current annual rate, Remaining term on current loan, New annual rate, New loan term, Refinance closing costs, and Cash-out amount. Keep all monetary inputs in the same currency; the currency selector formats results and does not perform foreign-exchange conversion. Enter percentage or rate fields on the scale displayed by the form; do not silently convert them to a different percentage or decimal convention. Keep the time period shown on the form consistent with the source value; convert it first if your source uses a different period. Before calculating, recheck Current loan balance, Current annual rate, Remaining term on current loan against the source values you intend to model. Use the labels on Mortgage Refinance Calculator as the source of truth and recheck any prefilled value before relying on the result.

How the calculation works

The calculator computes old and new amortizing payments, the monthly payment difference, new loan balance after any cash-out, modeled interest, and a simple break-even period based on closing costs divided by monthly savings when savings are positive. Mortgage Refinance Calculator applies that relationship only to the inputs represented on its form. If the result looks surprising, verify the entered values, units, and signs before interpreting the number.

Example

If refinancing lowers a monthly payment by $200 and closing costs are $4,000, the simple payment-savings break-even is 20 months, before considering the changed loan term, interest profile, or cash-out. The example is a math check for Mortgage Refinance Calculator; replace the sample values with your own inputs rather than treating the example as a target or recommendation.

How to interpret the result

A lower payment can come from a lower rate, a longer term, or both. Break-even is most useful when paired with total interest and the expected time you will keep the refinanced loan. A change in the result should be traced back to the input that changed before you draw a practical conclusion.

Limitations and notes

Refinance decisions also depend on points, prepaid items, escrow, taxes, mortgage insurance, appraisal, qualification, cash-out pricing, reset of the amortization clock, and the opportunity cost of closing costs. The safest way to reuse this calculation later is to keep the source values and date with the result.