Loan Interest Comparison Calculator
Compare two or more loan offers side by side by principal, rate, and term to see monthly payment, total interest, and total cost — with the lowest-interest offer highlighted.
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| Offer | Monthly Payment | Total Interest | Total Cost |
|---|---|---|---|
| Lender A Lowest Interest | $489.15 | $4,349.22 | $29,349.22 |
| Lender B | $413.14 | $4,746.30 | $29,746.30 |
How to Use the Loan Interest Comparison Calculator
List two or more loan offers with each one's principal, annual interest rate, and term in months. For every offer, the calculator computes the standard amortized monthly payment, then multiplies it by the term to get the total cost, and subtracts the principal to isolate total interest paid. The offer with the lowest total interest — not necessarily the lowest monthly payment or the lowest rate — is highlighted so you can see which loan actually costs you the least over its full life.
Total Interest = (Monthly Payment × n) − P
Example
A $25,000 loan at 6.5% over 60 months costs about $489/month and roughly $4,340 in total interest. A competing offer of the same $25,000 at a lower 5.9% rate but stretched to 72 months costs less per month (about $412) but accrues roughly $4,650 in total interest — slightly more than the shorter, higher-rate offer, because of the longer time the balance accrues interest.
Common Use Cases
- Comparing two or more auto, personal, or personal loan offers side by side before signing.
- Seeing how a lower rate but longer term can sometimes cost more in total interest than a shorter, higher-rate offer.
- Negotiating with a lender using a concrete total-interest figure instead of comparing rates alone.
FAQs
- Why does the highlighted offer have the lowest interest instead of the lowest payment? The lowest monthly payment often comes from stretching the term out, which usually increases total interest paid. This tool highlights whichever offer costs the least in total interest over the life of the loan, since that's the truest measure of which loan is cheapest.
- Can I compare more than two offers at once? Yes — use the "Add Loan Offer" button to add as many offers as you want to compare side by side in the same table.
- Does this include fees like origination charges? No — this compares principal, rate, and term only. If a lender charges an origination fee or other upfront costs, add that to your own comparison separately, since it isn't reflected in the total interest shown here.