Interest Rate Comparison Calculator: Which Loan Is Better?

A loan quote gives you three levers and they don't move together. The rate sets how fast interest accrues. The term sets how long it accrues for — and, through that, what you pay each month. The fees accrue nothing at all; they're simply money handed over on the day you sign.

Change one lever and both scoreboards move in the same direction, so the comparison is easy. Change two and they can split. A lower rate on a longer term almost always produces a smaller monthly payment and a larger interest bill, and the offer that looks generous on the statement is the one that costs more. That's why the calculator reports cost of credit — interest plus fees, principal excluded — as the price of the loan, and treats the monthly payment as a separate question about what fits your budget.

Both scoreboards matter. The one you should never do is read the payment and conclude something about the price.

Load the auto loan preset above. Offer B is quoted at half a point below Offer A — an unambiguously better rate — and its payment is nearly ninety dollars a month lower. It also charges more total interest, because it runs twelve months longer. The rate improved and the loan got more expensive.

This is the single most common way a rate comparison goes wrong, and it's why dealers and lenders quote monthly payments rather than totals. A stretched term shrinks the payment and enlarges the interest, and the two effects are easy to confuse when only one of them shows up on the paperwork you sign. Compare terms first; compare rates within the same term.

The one honest defense of the longer term is cash flow. A payment you can always make is worth real money, and nothing here says otherwise — just know the price. And the longer term costs less than the schedule implies if you overpay it: extra principal on a fully-amortizing loan retires interest for the loan's whole remaining life. The auto loan payoff calculator models that with the daily interest accrual most car loans actually use, and the personal loan payoff calculator does the same for an installment loan.

An origination fee is interest paid in advance. A lender offering a lower rate for a fee is selling you a discount, and like any discount bought with cash, it only pays off if you use it long enough. Divide the fee by the monthly payment saving and you get the break-even month — the point where the savings have repaid the fee and every month after is profit.

That number is a forecast about your behavior, not just the loan. Break-even at month 32 of a 60-month personal loan is a good trade if you carry the loan to term. It's a bad one if you expect a bonus in year two and intend to clear the balance early, because you'll have paid the fee and collected less than half of what it bought. The calculator flags the case where break-even lands past the point both loans would still be running — there, the fee never pays for itself at all.

The same logic explains why APR isn't a complete answer. APR spreads the fees across the loan's full term to express them as a rate, which is a fair summary only if you actually keep the loan that long. For a loan you might retire early, the break-even is the number that tells you something APR can't.

Comparing two consolidation offers against each other is only half the decision. The other half is whether the winner beats the debts it would pay off. A loan at 10.49% is a clear improvement on a stack of credit cards in the low twenties — but not on a car loan at 6% that got swept into the same refinance because it was convenient.

Run the offer you picked here through the debt consolidation calculator, which weights your existing balances into a blended rate and compares it against the new loan on both interest and payoff date. Then read when debt consolidation makes sense for the conditions that have to hold beyond the arithmetic — chiefly that the freed-up cards stay at zero. A consolidation loan that lowers your rate and refills the balances it paid off has not saved you anything; it has doubled your debt at a better price.