Loan Comparison Calculator
Two loan offers can look similar on the monthly payment yet differ by thousands in what you actually pay. This calculator puts up to four offers side by side and shows each one's monthly payment, total interest, and total cost, then highlights the loan that costs the least overall. Adjust the amount, interest rate, and term for each offer to compare apples to apples — or to see how a lower rate stacks up against a shorter term.
| Loan | Amount (USD) | Rate % | Years | Monthly | Total interest | Total cost | |
|---|---|---|---|---|---|---|---|
| A | $1,580.17 | $318,861.22 | $568,861.22 | ||||
| B | $1,498.88 | $289,595.47 | $539,595.47 | ||||
| C✓ cheapest | $1,863.93 | $197,343.88 | $447,343.88 |
💡 The lowest monthly payment is not always the cheapest loan. A longer term lowers the monthly figure but can raise the total interest — compare the total cost column, highlighted above, to see which loan actually costs less overall.
How it works
Each offer is run through the standard reducing-balance payment formula. The monthly payment is what most lenders advertise, but it is a poor way to compare loans: a longer term lowers the monthly figure while quietly increasing the total interest. The total cost column — the monthly payment multiplied by the number of payments — is the honest comparison, and the calculator marks the lowest one.
Because the math is identical in any currency, you can compare offers from different lenders or countries by switching the display currency at the top of the page.
For each loan, monthly payment = P · i · (1 + i)^n / ((1 + i)^n − 1) with i = annual rate ÷ 12 ÷ 100 and n = years × 12. Total cost = monthly payment × n; total interest = total cost − P. The cheapest loan is the one with the lowest total cost, not the lowest monthly payment.
Worked example
Compare three offers on the same 250,000 loan: (A) 6.5% over 30 years, (B) 6.0% over 30 years, and (C) 6.5% over 20 years. Offer C has the highest monthly payment but the lowest total cost, because the shorter term means far less interest. Offer B beats A thanks to the lower rate. The lowest monthly payment (A) is the most expensive loan overall — exactly the trap the total-cost column exposes.
Things to watch out for
This compares principal and interest only. Fees, origination charges, insurance, and prepayment penalties can change which loan truly wins — fold those into the amount or compare the lender's APR, which bundles many fees. Also weigh affordability: the cheapest total cost may carry a monthly payment you cannot comfortably sustain.
Frequently asked questions
Why isn't the lowest monthly payment the best deal?+
A low monthly payment usually comes from a longer term, which means you pay interest for more years. Stretching a loan out can add a large amount of total interest even when the rate is the same, so always compare total cost.
How many loans can I compare?+
Up to four at once. Add or remove offers to match the deals you're weighing.
Does a lower interest rate always win?+
Not necessarily. A lower rate over a much longer term can still cost more in total than a slightly higher rate over a shorter term. The total-cost column settles it.
Should I include fees?+
This tool compares principal and interest. To account for fees, either add them to the loan amount or compare each lender's APR, which expresses the rate including many standard fees.
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Disclaimer: This calculator is for educational and informational purposes only and provides estimates, not financial advice. Interest rates, taxes, fees, and local rules vary and change over time. Confirm figures with a qualified professional before making any financial decision.
Last reviewed: 2026-06-22