Mortgage Comparison Calculator
Put two mortgages side by side and see which costs less over its life.
Mortgage Offer One
Mortgage Offer Two
Comparison Results
Choosing between two mortgage offers means weighing the monthly payment against what you'll pay over the whole term — and a lower rate doesn't always win once the loan amount or length differs. This calculator puts both loans side by side, working out each one's monthly payment, total interest, and total cost, then highlights the cheaper figure and shows how much interest the better option saves. Enter each loan's amount, rate, and term in years; it all runs in your browser.
The amortisation formula it uses
Each mortgage is priced with the standard fixed-rate amortisation formula, where the annual rate is divided by twelve for a monthly rate r and the term becomes n monthly payments:
Monthly = P × r × (1 + r)ⁿ ÷ [(1 + r)ⁿ − 1]
The total cost is the monthly payment times the number of payments, and the total interest is that total minus the amount borrowed. The calculator marks the lower monthly payment, the lower total interest, and the lower total cost, and if the two differ it shows the interest saved by the cheaper loan. That lets you see, for example, how a shorter term with a higher payment can still cost far less overall.
What the comparison leaves out
This compares principal and interest only. A real mortgage decision also involves closing costs, points, private mortgage insurance, property taxes, and homeowners insurance, none of which are included here. Adjustable-rate loans will also drift from the fixed figure once the rate resets. Use the comparison to understand the core trade-off between rate, amount, and term, then layer in fees and escrow from each lender's official estimate before deciding.
Frequently Asked Questions
Does a lower interest rate always mean the cheaper loan?
Not necessarily. A lower rate can still cost more in total if the loan amount is larger or the term is longer. Comparing total interest and total cost — not just the rate — is the point of this tool.
Are taxes and insurance included in the payment?
No. The figures cover principal and interest only. Property taxes, homeowners insurance, PMI, and closing costs are separate and vary by lender and location.
Can I compare a 15-year loan against a 30-year loan?
Yes. Enter different terms for each side. You'll typically see the shorter term has a higher monthly payment but much lower total interest.
Is my information saved?
No. The comparison is calculated in your browser and nothing you enter is uploaded or stored.