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~6 min readHow to Calculate Loan Payments Online
A loan calculator does not just tell you the monthly payment — it shows you the true cost of borrowing. That total interest figure over the full loan term is often significantly larger than people expect, and seeing it before signing changes the conversation.
How to use the Loan Calculator
Open the Loan Calculator and enter three values:
- Loan amount — the principal you are borrowing
- Annual interest rate — the percentage rate, not the APR (though for simple loans they are often close)
- Loan term — the number of months or years over which you will repay
The calculator returns the fixed monthly payment, the total amount paid (principal plus interest), and the total interest paid over the life of the loan. This is the standard amortisation calculation used by banks and lending institutions.
Understanding amortisation
Amortisation is the process of spreading a loan repayment over time with fixed payments. Each payment has two components: interest on the outstanding balance, and principal reduction. Early in the loan term, most of each payment is interest. Late in the term, most is principal.
This is why making extra payments early in a loan term reduces total interest paid more effectively than extra payments made later. On a 30-year mortgage, an extra £200 per month in the first year can save more than £10,000 in total interest compared to the same extra payment made in year 20.
Comparing loan terms
Run the calculator multiple times with different terms to see the trade-off. For example, a £15,000 car loan at 7% annual interest:
- 36-month term: monthly payment £463, total interest £1,668
- 48-month term: monthly payment £358, total interest £2,194
- 60-month term: monthly payment £297, total interest £2,772
The 60-month term has a £166 lower monthly payment than the 36-month term but costs £1,104 more in total interest. Whether that trade-off is worth it depends on your cash flow, but the calculator makes the numbers explicit before you decide.
Other financial calculators to use alongside
Loan calculations rarely happen in isolation. Combine the Loan Calculator with these related tools for a fuller picture:
- The Compound Interest Calculator shows how savings or investments grow if the interest is reinvested — the other side of the borrowing equation.
- The Percentage Calculator helps quickly check what percentage of a monthly salary a loan payment represents.
- The Profit Margin Calculator is useful for business loans where the loan finances income-generating activity.
Browse all financial tools on the Calculator Tools category page.
How to Calculate Loan Payments Online FAQs
What is the difference between interest rate and APR?
The interest rate is the cost of borrowing the principal expressed as a percentage. APR (Annual Percentage Rate) includes the interest rate plus additional fees like origination fees, arrangement fees, and broker fees. APR gives a more complete picture of the total borrowing cost. The Loan Calculator uses the interest rate — for the most accurate comparison of loan offers, use each lender's published APR.
Does the loan calculator account for fees?
No. The calculator uses the standard amortisation formula applied to the principal and interest rate. Fees are not included. Add any upfront fees to the loan amount if you want to estimate the effective total cost including fees.
What is a good interest rate for a personal loan?
This varies significantly by country, economic conditions, and borrower credit history. In the UK, personal loan rates in 2025 range from around 6% to 30%+ depending on the lender and borrower profile. In the US, rates typically range from around 7% to 35%. The best rate available to you depends on your credit score and the lender's criteria.
Can I use this calculator for a mortgage?
Yes, for a basic fixed-rate mortgage calculation. Enter the principal, the annual interest rate, and the term in months (a 25-year mortgage is 300 months). Note that real mortgages often involve product fees, insurance requirements, variable rate changes after an initial fixed period, and other factors not captured in a simple amortisation calculation.
Related tools
Ready to try it yourself? Start with the tools below or browse the full tools directory.
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