Mortgage Comparison Calculator

Written by Great Medico

Updated September 25, 2026 •3 min read

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A headline number is more useful when you can see what created it. Mortgage Comparison Calculator compares two mortgage offers using each offer’s rate, term, and closing-cost assumptions for the same loan amount, keeping the calculation tied to the values on the form.

What this calculator does

Mortgage Comparison Calculator compares two mortgage offers using each offer’s rate, term, and closing-cost assumptions for the same loan amount. The visible inputs are loan amount to compare, option a mortgage rate, option a term, option a closing costs, option b mortgage rate, option b term, and option b closing costs. 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 Loan amount to compare, Option A mortgage rate, Option A term, Option A closing costs, Option B mortgage rate, Option B term, and Option B closing costs. 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 Loan amount to compare, Option A mortgage rate, Option A term against the source values you intend to model. Use the labels on Mortgage Comparison Calculator as the source of truth and recheck any prefilled value before relying on the result.

How the calculation works

The calculator computes the amortizing payment and lifetime interest for option A and option B, adds the entered upfront costs, and compares monthly payment and total modeled cost. Mortgage Comparison 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

For the same $300,000 loan, a 30-year 6.5% option may have a lower monthly payment than a 15-year 5.9% option, while the shorter term can produce much less lifetime interest. Closing costs can change the comparison further. The example is a math check for Mortgage Comparison Calculator; replace the sample values with your own inputs rather than treating the example as a target or recommendation.

How to interpret the result

No single output makes one loan universally better. Monthly affordability, expected holding period, total interest, upfront cash, and refinance plans can point in different directions. Read the output together with the component figures rather than treating the headline value as a complete decision rule.

Limitations and notes

APR, points, mortgage insurance, escrow, tax effects, rate-lock terms, prepayment features, and the time value of upfront costs may not be fully captured. Compare actual lender Loan Estimates before choosing. If the result will support a real transaction, compare it with the lender, broker, payroll, tax, or contract documents that actually govern the transaction.