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Loan calculator: monthly payment and amortization

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Estimate only: this is not a loan offer. The real APR (annual percentage rate) includes fees that are not calculated here, such as origination fees or closing costs.

A loan and mortgage calculator that runs in your browser

This loan calculator handles fixed-rate loans repaid in equal monthly installments: a mortgage, a car loan or a personal loan. Under “Calculate”, pick one of three questions. “Monthly payment” uses the loan amount, rate and term. “How much I can borrow” starts from the payment you can afford. “Loan term” tells you how long a given payment takes to clear a balance. Nothing you type leaves your device.

Amounts are shown in US dollars by default; the “Currency” menu switches to pounds sterling or euros.

How to use it

  1. Choose what to calculate, then fill in “Loan amount”, “Monthly payment you can afford”, “Annual interest rate” and “Loan term” (in years or months). Commas are fine: “300,000” and “6.5” both work.
  2. Tick “Loan insurance” to add a fixed monthly insurance cost based on a yearly percentage of the amount borrowed. In the borrowing and term modes, the payment you enter then includes that insurance.
  3. Tick “Extra monthly payment” to see how paying a bit more each month shortens the loan and how much interest it saves.
  4. Open “Amortization schedule”, switch between “Monthly” and “Yearly”, and use “Export to CSV” to open it in a spreadsheet. “Copy link to this calculation” gives you an address that reopens the page with your figures.

How the monthly payment is calculated

For a loan of P at a monthly rate r (the annual rate divided by 12) over n months, the payment is M = P × r ÷ (1 − (1 + r)^−n). Each month, interest is charged on the balance still owed, and the rest of the payment reduces the principal.

Example: a $300,000 mortgage at 6.5% over 30 years, which is 360 payments at a monthly rate of about 0.5417%. The payment is $1,896.20. In month one, interest is $300,000 × 6.5% ÷ 12 = $1,625.00, so only $271.20 goes toward the principal. Over the full term you pay $382,636.71 in interest, and $682,636.71 in total. Because the payment is rounded to the cent, the final one is adjusted to $1,900.91.

At 0% interest the payment is simply the amount divided by the number of months.

Reading an amortization schedule

Each row shows the payment, the interest part, the principal part and the remaining balance. Early on, interest takes most of each payment because the balance is still large: in the example, year one costs $19,401.28 in interest against $3,353.12 of principal repaid. The chart shows the shift: the balance line falls slowly at first, then faster and faster.

How term and rate change the cost

$300,000 borrowedMonthly paymentTotal interest
6.5% over 15 years$2,613.32$170,398.28
6.5% over 30 years$1,896.20$382,636.71
6% over 30 years$1,798.65$347,515.44

A 15-year term costs $717.12 more per month but saves $212,238.43 in interest. Half a point off the rate on a 30-year loan lowers the payment by $97.55 and the interest by $35,121.27.

Insurance, taxes and fees

Lenders may require some form of insurance, and a mortgage payment often also covers property taxes and homeowners insurance through an escrow account. This calculator only adds the optional insurance line you enter. Origination fees, points and closing costs are not included; they are part of the APR, the rate that reflects the real yearly cost of the loan, which is why the APR is higher than the interest rate.

How much can you afford?

Lenders look at the share of your income that goes to debt repayments, and each lender sets its own limits. With “How much I can borrow”, a payment of $1,000 a month at 4% over 20 years corresponds to a loan of $165,021.86.

Paying the loan off early

Adding $200 a month to the $300,000 loan at 6.5% clears it in 277 months instead of 360, which is 6 years and 11 months sooner, and saves $103,450.19 in interest. Some contracts charge a prepayment penalty, depending on the loan and local rules, so check your agreement first.

Frequently asked questions

Is this a loan offer?

No. It is an estimate. Your actual rate, insurance and fees depend on your situation and on the lender.

Why is the last payment different?

The payment is rounded to the cent, so tiny differences add up and the final payment settles the exact balance. The last row of the schedule always shows a remaining balance of $0.00.

How long does it take to repay $150,000 at $900 a month?

At 3%, the “Loan term” mode shows 18 years (216 months), with a final payment of $781.28 and $44,281.28 in interest.

Can I use it for a car loan?

Yes. Enter the amount financed after your down payment, the rate and a term in months, such as 60.