See the real cost of borrowing money.
Estimate how much interest you could pay on a loan and understand the relationship between the amount borrowed, interest rate and repayment term. Adjust the figures to compare different borrowing scenarios.
Track the interest
See how the cost of borrowing can change when you adjust the rate or repayment period.
Calculate the interest on your loan.
Enter your own figures to estimate the monthly repayment, total interest and overall amount repayable. Results only appear after you run the calculation.
Loan details
Enter the figures you want to compare.
Loan interest
Your personalised estimate will appear after calculation.
What does loan interest actually mean?
Loan interest is the amount charged by a lender for providing you with access to borrowed money. The rate is usually expressed as an annual percentage, although the actual interest calculation depends on the loan structure and payment schedule.
For a typical amortising loan, each repayment contains a portion that reduces the outstanding principal and a portion that covers interest. As the principal falls, the amount of interest charged on the remaining balance can also change.
The interest rate is one of the most important factors in determining the total cost of borrowing. A higher rate generally means more interest over the life of the loan, all else being equal.
The repayment term matters too. Extending the term can reduce the regular payment, but it can also mean that interest is charged for a longer period.
This calculator provides an estimate based on the figures you enter. Actual lender calculations may differ because of fees, rate structures, payment dates and other terms in the agreement.
What affects the interest you pay?
Understanding the main variables can help you compare borrowing options more confidently.
Loan Amount
A larger principal means there is more money on which interest may be charged. Borrowing only what you need can help control the overall cost.
Interest Rate
The rate directly affects the cost of borrowing. Even a modest change in the rate can affect total interest, especially on larger or longer loans.
Loan Term
A longer term spreads repayments over more periods. This may lower each payment while increasing the time over which interest can accumulate.
Fees
Arrangement fees and other charges can add to the overall cost. Check the lender's complete terms before comparing offers.
Repayment Schedule
The timing and frequency of payments can affect how interest is calculated under particular loan terms.
Credit Profile
Your circumstances and credit history can influence the rates and products that may be available to you.
Don't judge a loan by the monthly payment alone.
A repayment that looks manageable can still result in a higher total cost if the loan runs for longer. Look at the interest and total repayment alongside the monthly figure.
How the repayment term can change your total cost.
The same borrowing amount can have a very different total cost depending on how long you take to repay it.
Higher regular payment
A shorter repayment period can mean larger regular payments, but you may pay less interest overall.
Lower regular payment
A longer term can reduce the regular payment, but interest may be charged for a longer period.
Look at the total cost
Compare monthly repayment, total interest and total amount repayable rather than focusing on one number.
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Loan Interest Calculator FAQs
Answers to common questions about loan interest, repayments, rates and borrowing costs.
Know your interest. Understand your borrowing cost.
Run different scenarios using your own loan amount, interest rate and repayment term before comparing borrowing options.