What do the two default offers show?
The calculator opens with a comparison worth walking through. Both offers are for $300,000. Offer 1 is 6.5% over 30 years, and Offer 2 is 5.75% over 15 years. Run the numbers and Offer 1 costs $1,896 a month while Offer 2 costs $2,491, so the longer loan is $595 a month easier to live with. Then look at the other columns. Offer 1 accumulates $382,633 in interest for a total cost of $682,633. Offer 2 accumulates $148,421 for a total of $448,421. Choosing the smaller payment costs about $234,000 over the life of the loan, roughly three quarters of the amount originally borrowed. Neither choice is wrong. Offer 1 protects your monthly budget, and Offer 2 protects your long-run wealth, so the question is which kind of pressure you can actually afford. What the default comparison teaches is that the monthly payment and the total cost usually point in opposite directions, and a decision made on the payment alone is only half a decision.
Which number should you trust, the rate or the APR?
The rate and the annual percentage rate describe the same loan from two angles. The rate sets your monthly payment and nothing else. The APR restates the cost of the loan as a yearly percentage after folding in most upfront fees, points, and certain closing charges, so it usually ranks two fixed-rate loans of the same length more honestly than the rate does. A 6.25% loan with two points can carry a higher APR than a 6.5% loan with no points, and when it does, the second loan is the cheaper one despite its bigger headline number.
APR has one blind spot. It spreads the upfront fees across the full term, so it assumes you keep the loan to maturity. Pay off early, through a sale or a refinance, and those fees weigh more than the APR implied. A borrower who expects to move within a few years should lean toward the low-fee offer even when its APR is slightly worse. Note also that survey rates like Freddie Mac's weekly average are quoted with points attached, so your own no-point quotes may sit a little above them without anything being wrong.
How do fees and points flip the answer?
This tool compares principal and interest only, and the fee sheet is where many comparisons are actually decided. Origination fees, discount points, underwriting charges, and prepaid items can differ by thousands of dollars between two offers with nearly identical rates. The fix is a break-even test. Take the extra upfront cost of the lower-rate offer and divide it by the monthly amount it saves. The result is how many months you must keep the loan before the lower rate has earned its fees back.
Concretely: on a $300,000 loan, one point costs $3,000 and typically buys the rate down around a quarter of a percentage point, which saves about $49 a month at these balances. Two points for $6,000 saving $100 a month break even at 60 months. Keep the loan past five years and the points were a good buy. Leave sooner and they were a donation to the lender. The FTC's consumer advice has warnings on the uglier version of this pattern, where low advertised rates hide fees that never pay for themselves. Add each offer's fees to its total cost from this calculator before deciding, because the fees are frequently the deciding margin.
How do you compare loans with different terms fairly?
Payment against payment is the wrong contest when the terms differ, because the shorter loan will always look expensive by the month and cheap by the decade. The default offers show it: the 15-year loan asks $595 more every month and finishes $234,000 ahead. So compare on total interest and total cost, then treat the monthly gap as a separate affordability question rather than a measure of which loan is better. If the honest answer is that the higher payment would squeeze out your savings or leave no slack for a rough month, the longer term is buying you real security and the extra interest is its price. If you can carry the higher payment comfortably, the shorter term keeps a great deal of money in your hands. There is also a middle route: take the longer loan for its lower required payment, then pay it on the shorter loan's schedule whenever you can. You capture most of the interest saving while keeping the smaller obligation as a fallback. Whichever way you lean, decide on the total cost with fees folded in, since that is the figure that actually leaves your account.