Personal Loan Calculator: What You'll Really Pay

The monthly payment is a distraction (sort of)

Here's the trick lenders love. They advertise the monthly payment in big friendly numbers — "$289 a month!" — and bury the total cost in the fine print. A low monthly payment feels affordable. And it is, month to month. But stretch that loan over six years instead of three and you can easily pay double the interest for the same borrowed amount.

That's exactly why a personal loan calculator exists. Punch in the numbers and it shows both sides: what leaves your bank account each month and what the loan costs all-in. The monthly number tells you if you can afford it. The total tells you if you should.

The three numbers that actually matter

Every personal loan boils down to three inputs and two outputs. The inputs:

• Loan amount — what you're borrowing. Obvious, but borrow only what you need. Every extra thousand costs you interest for years.
• Interest rate (APR) — the yearly cost of borrowing, expressed as a percentage. This is where your credit score does its damage or its magic.
• Term — how long you take to repay, usually 2 to 7 years for personal loans. Longer term = smaller payment, much bigger total cost.

And the two outputs you actually care about:

• Monthly payment — can your budget handle it without stress?
• Total interest — the true price tag of the loan. This is the number most people never check, and it's the one that matters most.

If you want the mechanics behind these numbers, our guide on how loan interest is calculated walks through the actual formulas.

Let's run a real example together

Say you borrow $12,000 at 11% APR for 4 years (48 months). A personal loan calculator gives you roughly $310 a month. Feels manageable, right?

Now the part people skip: $310 × 48 months = about $14,880 total. Subtract the $12,000 you borrowed and you've paid roughly $2,880 in interest — nearly three grand just for the privilege of borrowing.

Now watch what happens if you stretch it to 6 years instead. The payment drops to around $228 a month — nice and comfy. But total interest climbs to roughly $4,450. You "saved" $82 a month and paid about $1,560 extra for the privilege. Lenders love long terms. Your wallet shouldn't.

Payments on common loan amounts

Here's what a personal loan costs at a 15% APR, a middle-of-the-road rate, over the two most popular terms:

The pattern holds at every size: going from 3 to 5 years cuts the payment by roughly a third but adds about 70% more interest.

Rates by credit score: what $10,000 really costs

Your credit score moves the price of a loan more than anything else you control. NerdWallet's October 2026 data on pre-qualified offers puts average personal loan APRs at:

So how much interest would you pay on a $10,000 loan with a 620 credit score? At the bad-credit average, about $6,300 over three years or $11,300 over five, more than the loan itself. The same loan with excellent credit costs about $2,500 over three years. That gap is why improving your score before you borrow is often the best money you'll ever "make."

Averages are estimates from NerdWallet (updated October 1, 2026). Your actual rate depends on the lender, your income and your existing debt.

How personal loan interest is calculated

Almost every personal loan is a fixed-rate installment loan with simple interest on a declining balance. Each month, the lender charges interest on what you still owe, and the rest of your payment pays down the principal. The payment itself comes from one standard formula:

Monthly payment = P × r × (1 + r)ⁿ ÷ ((1 + r)ⁿ − 1)

Here P is the amount you borrow, r is the APR divided by 12, and n is the number of months. For $12,000 at 11% over 48 months, r = 0.00917 and the payment comes out to $310.15.

Because interest is charged on the remaining balance, early payments are mostly interest and later ones are mostly principal. That's also why extra payments early in the loan save the most. Our amortization guide shows the month-by-month split.

Why your rate won't match the advertised rate

Ever seen an ad screaming "rates from 6.99%!" and then gotten quoted 14%? Yeah. That "from" is doing a lot of heavy lifting. The advertised rate goes to borrowers with excellent credit, steady high income, and low existing debt. Everyone else pays more.

Your actual rate depends on your credit score, income, debt-to-income ratio, and sometimes the loan purpose. Before you apply anywhere, check your credit score — it's free through most banks and credit card apps now. Even a few months of paying down balances can move your rate enough to save real money. Our guide on improving your loan eligibility covers the levers you can pull.

Watch out for origination fees

Some lenders charge an origination fee — usually 1% to 8% of the loan — just for setting it up. Sometimes it's deducted from your loan amount, so you borrow $12,000 but only receive $11,400. Sometimes it's rolled into the balance, so you're paying interest on the fee itself.

Either way, compare the APR — not just the rate — when shopping lenders, since APR is supposed to include fees. And if a lender won't clearly tell you the total cost? Walk away.

General information only, not financial advice. Loan terms and rates vary by lender and borrower.