How this instrument works
A mortgage quote is never just a rate. Every lender is required to hand over a Loan Estimate that itemizes closing costs alongside the rate and term, and those figures move independently — a slightly higher rate can carry noticeably lower fees, or a 15-year term can demand a bigger monthly payment while erasing years of interest. This instrument runs the standard fixed-installment formula on each offer using its own amount, rate, and term, multiplies the result by the number of payments, then adds each side's own closing costs on top, so the two totals mean the same thing: every dollar that leaves your pocket from signing to the final payment.
The person running this comparison is usually a buyer holding two Loan Estimate forms from competing lenders, or an existing owner weighing a refinance offer against the mortgage already in place, or a buyer deciding between a 30-year term at one rate and a 15-year term at a lower one from the same bank. The habit that gets people into trouble is anchoring on a single figure — the advertised rate, the smaller closing bill, or the payment that fits the monthly budget — because none of those three numbers by itself says which offer hands over more money by the time the loan is retired. A rate that looks half a point better can still lose once its closing costs and its longer accrual period are counted.
Total cost here is principal, interest, and each side's own closing costs, computed from the amount, rate, and term entered — nothing more. It leaves out property tax, homeowner's insurance, private mortgage insurance, HOA dues, and any points or lender credits folded into the closing figure rather than itemized separately, and it assumes both offers repay as equal monthly installments through the full term rather than an interest-only or adjustable structure. Two offers with very different terms will always show a wide gap here, because more months means more interest, regardless of which rate looked better on the page.
- Enter the first lender's numbers under Loan A amount, $, Loan A rate, %, and Loan A term, years, then copy Loan A closing costs, $ straight from that Loan Estimate.
- Enter the second lender's numbers the same way, under Loan B amount, $, Loan B rate, %, Loan B term, years, and Loan B closing costs, $.
- Compare Loan A total cost (payments + closing) against Loan B total cost (payments + closing) rather than the rate or the payment alone.
- Read Total cost difference (A − B): a positive figure means Loan A costs more overall, a negative one means Loan B does.
- Change Loan A term, years or Loan B term, years to see how much a shorter payoff window is worth once its higher payment and its own closing costs are counted.
Worked example — 30 years at 6.5% against 15 at 6.0%
Loan A finances $300,000 at 6.5% over a 30-year term, with Loan A closing costs, $ set to 5,000. That prices out to a monthly principal-and-interest payment of $1,896.20 across 360 payments, and adding the closing figure brings Loan A total cost (payments + closing) to $687,633.47 — roughly $382,633 of that is interest, more than the amount borrowed.
Loan B finances the same $300,000 at a lower 6.0% rate but over 15 years instead of 30, with Loan B closing costs, $ set to 6,000 — a thousand dollars more than Loan A's. Its monthly payment runs higher, at $2,531.57 across 180 payments, yet Loan B total cost (payments + closing) comes to only $461,682.69. Total cost difference (A − B) works out to $225,950.78: the 30-year offer costs almost a quarter of a million dollars more by payoff, despite its lower headline rate and its cheaper closing bill.
Questions
Why does the loan with the lower monthly payment end up costing more?
Because a lower payment usually means a longer term, and interest keeps accruing on the unpaid balance every one of those extra months. In the worked example, Loan A's payment is $635 a month lower than Loan B's, but it runs for 180 more months, and that extra stretch of accrual outweighs the smaller payment by roughly $225,950 in Total cost difference (A − B).
Do closing costs actually change which mortgage wins?
Sometimes, especially when the two offers are close in rate and term. Here, Loan B's closing costs were $1,000 higher than Loan A's, yet Loan B still cost $225,950.78 less overall, because the 15-year term's interest savings dwarfed a four-figure fee gap. Closing costs matter most when comparing two offers with similar terms, where a fee difference of a few thousand dollars is not swamped by decades of interest.
Should I pick the lower rate or the lower total cost?
This instrument reports Loan A total cost (payments + closing) and Loan B total cost (payments + closing) so both are on the table, but it does not rank them for you. A lower total cost means less money changes hands by payoff; a lower rate with a lower payment can still be the more livable choice if the higher payment on the cheaper-overall loan would strain a monthly budget.
What if I plan to sell or refinance before either loan is paid off?
Then total cost through full payoff overstates what either loan actually costs you, since a shorter-term offer front-loads more principal into each payment while a longer-term offer front-loads more interest. Selling or refinancing after five or ten years favors whichever loan built more equity by that point, which this sheet does not isolate — it prices both mortgages to their final payment.
Does Loan A total cost (payments + closing) include property tax or insurance?
No. It is principal, interest, and the closing costs entered for that side only. Property tax, homeowner's insurance, private mortgage insurance, and HOA dues vary by location and policy and are not part of either lender's rate quote, so they are left out here and should be added from your own escrow estimate before comparing what either mortgage truly costs month to month.
Why do two lenders quote different closing costs on the same loan amount?
Origination fees, underwriting fees, discount points, and title charges are each set by the lender or a third party the lender selects, and they are not standardized the way the interest calculation is. A federal Loan Estimate form itemizes them so they can be checked line by line — comparing the itemized totals, not just the number at the bottom, shows which fees are actually negotiable.
References
- Consumer Financial Protection Bureau — Loan Estimate explainer
- Federal Reserve — Consumer's guide to mortgage settlement costs
Read this first: This instrument shows arithmetic, not advice. Real offers add fees, taxes and terms that vary by lender and place — verify the figures against your actual paperwork before deciding anything.