Loan Calculator — compare rates & terms side by side

How it works

This calculator takes one loan amount and runs it through two or three scenarios — each a rate and a term — so you can compare them directly. For each scenario the monthly payment comes from the amortization formula, M = P·r(1+r)ⁿ ⁄ ((1+r)ⁿ − 1) — P the loan amount, r the monthly rate (the annual rate divided by 12), and n the number of payments — and the total cost is that payment multiplied by the number of payments, the amount you repay over the whole loan. Comparing scenarios makes the two levers visible: a longer term shrinks the monthly payment but stretches interest over more years, so it usually costs more in total; a lower rate reduces both the payment and the total. The scenario with the lowest total cost is highlighted.

Worked example

A $250,000 loan at 6% over 30 years has a monthly payment of about $1,498.88 (LibreTexts). Kept to term, that is 360 payments totalling roughly $539,600 (LibreTexts) — more than double the amount borrowed, because interest accrues for thirty years. The same $250,000 over 15 years costs more each month but far less overall, since the balance is gone in half the time. Set the two against each other and the monthly-vs-lifetime trade-off is explicit rather than buried.

Frequently asked questions

What does this loan calculator compare?

It compares the monthly payment and total cost of one loan amount under two or three different rate-and-term scenarios. It is built for questions like "15-year vs 30-year?" or "is shopping for a rate half a point lower worth it?" — where you want to see the options next to each other.

How is each scenario's total cost calculated?

Each scenario's monthly payment comes from the standard amortization formula (the loan amount, the monthly rate, and the number of payments); its total cost is that payment multiplied by the number of payments — the full amount you repay. The total is what this page compares: a lower monthly payment often carries a higher total, and putting both numbers side by side for each scenario is the point.

Is a shorter term or a lower rate better?

It depends on what you are optimising. A shorter term raises the monthly payment but cuts total interest sharply; a lower rate helps both. The comparison highlights the lowest total cost, but the right choice also depends on what monthly payment you can comfortably afford — so weigh both columns.

Why does a 15-year scenario cost less overall than a 30-year?

Seen side by side at the same rate, the 15-year option carries a higher monthly payment but a much lower total cost: interest is charged on the outstanding balance, and a 15-year loan clears that balance in half the time, so far fewer months of interest accrue. Comparing whole loans this way surfaces the size of that monthly-versus-lifetime trade-off for your own amount and rates.

How is this different from the amortization calculator?

This page compares whole loans against each other — which one to take. The amortization calculator takes a single loan and shows how its balance unwinds month by month, splitting each payment into principal and interest. Use this to choose a loan, and amortization to understand the one you chose.

What should I put in the third scenario?

Scenario C is optional — leave its rate and term at zero to compare just two loans. Reveal it under advanced options when you want a third option in the mix, such as a second lender's quote or an in-between term.

How accurate is this, and what does it exclude?

The payments and totals are exact for fixed-rate loans held to term. It excludes fees and points rolled into some loans, variable rates, and early payoff — so treat the totals as a like-for-like comparison of the loans as quoted, and confirm the details against each lender's offer.