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SPCXTools

Loan Calculator

Work out your monthly payment, total interest and full amortization schedule for any fixed-rate loan.

Runs locally — files never leave your device

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How to use Loan Calculator

  1. 1Enter the loan amount, the annual interest rate and the term in years or months.
  2. 2Optionally add an extra monthly payment to see how much interest and time you save.
  3. 3Read the monthly payment, total interest, total amount paid and payoff time.
  4. 4Review the amortization schedule by year or by month, and download it as a CSV file for spreadsheets.

Calculate loan payments and interest

Before you take out a mortgage, car loan, student loan or personal loan, it pays to know exactly what it will cost. This loan calculator shows your fixed monthly payment, the total interest over the life of the loan, the total you will repay, and a complete amortization schedule. Add an extra monthly payment to see how much faster you could be debt-free. All calculations run in your browser; no financial data is sent anywhere.

Features

  • Monthly payment for any amount, rate and term (in years or months).
  • Total interest and total cost, with a bar showing how much of your money goes to interest.
  • Extra payments to model overpaying, with interest saved and the new payoff time.
  • Amortization schedule by year or by month, showing payment, principal, interest and remaining balance.
  • CSV export to open the full schedule in Excel, Google Sheets or Numbers.
  • Any currency — results are in the same units you enter.

Example

Borrowing 25,000 at 6.5% for 5 years gives a monthly payment of about 489.15. Over 60 payments you repay about 29,349, of which roughly 4,349 is interest. Paying an extra 100 per month clears the loan about 11 months sooner and saves several hundred in interest.

Understanding amortization

An amortizing loan is repaid in equal instalments. Each month, interest is calculated on the remaining balance, and the rest of the payment reduces the principal:

  1. Interest = remaining balance × annual rate ÷ 12
  2. Principal repaid = payment − interest
  3. New balance = old balance − principal repaid

Because the balance shrinks, interest falls every month and principal repayment rises — the reason why the schedule's interest column decreases while the principal column grows.

Tips for borrowers

  • Compare the total cost, not just the monthly payment. A longer term lowers the payment but usually costs much more interest overall.
  • Small rate differences matter. On a 30-year mortgage, half a percentage point can change total interest by tens of thousands.
  • Overpay early. Extra payments in the first years save the most interest.
  • Check the fine print for fees, variable rates and early-repayment charges, which this calculator does not include.

For quick percentage questions — such as how much a rate change represents — use the Percentage Calculator.

Frequently asked questions

How is the monthly payment calculated?
The calculator uses the standard annuity formula for fixed-rate loans: payment = P × r ÷ (1 − (1 + r)^−n), where P is the loan amount, r is the monthly interest rate (annual rate ÷ 12) and n is the number of monthly payments. Each payment is the same, but the split between interest and principal changes over time.
Why do early payments go mostly to interest?
Interest is charged on the outstanding balance. At the start the balance is largest, so most of each payment covers interest. As the balance falls, less interest accrues and more of the payment reduces the principal. The schedule shows this shift month by month.
How much do extra payments save?
Extra payments go straight to the principal, which reduces all future interest. Even small amounts can shorten a long loan by years. Enter an amount in Extra monthly payment to see the interest saved and the new payoff time. Check that your lender doesn't charge early-repayment fees.
Does this include taxes, insurance or fees?
No. The result covers principal and interest only. Mortgages often add property tax, insurance and other costs to the monthly bill, and loans may have arrangement fees. Compare offers using the APR, which includes most fees.
What is the difference between interest rate and APR?
The interest rate determines the interest charged on the balance. The APR (annual percentage rate) also includes fees spread over the term, so it is the better figure for comparing loans. Enter the nominal interest rate here to calculate payments.
Which currency does it use?
Any. The calculator works with plain numbers, so enter amounts in your own currency and read the results in the same currency.

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