Compare on two measures
The monthly payment shows the immediate budget commitment. Total repaid shows principal plus modelled interest across the term. Read both together. These tools hold the interest rate constant so you can isolate the effect of the term.
Keep the rate definition consistent
Enter the nominal contractual borrowing rate. APR and APRC can include fees and other assumptions, so they are not necessarily the same input. Check the lender’s own repayment illustration for an actual offer and record upfront or financed fees separately.
Try a higher-rate scenario
For a mortgage, the rate offered for an initial period may not apply for the entire mortgage term. Run another calculation with a higher rate and see what it does to the payment. The result is a scenario, not a prediction of interest rates.
Do not confuse arithmetic with approval
A repayment calculator cannot determine how much a lender will offer, assess your household commitments or decide whether a product is suitable. It is a planning aid. For a personal decision, use the lender’s documentation and appropriate independent support.
Sources & methodology
- MoneyHelper: mortgage repayments
Repayment mortgages pay principal and interest; rate changes alter payments. No market rate is imported.
Checked 8 Oct 2026