Free calculator
Buy to let affordability calculator
Enter the rent, the property value and a product rate. The calculator shows the maximum loan a lender's rental stress test supports at 125% and 145% interest cover, and which constraint actually limits your borrowing.
Figures are illustrative only. They are not advice, not a quote and not an offer of finance. Lender criteria vary and change.
How the calculation works
Lenders test that the rent covers the mortgage interest with a margin. The margin is the interest coverage ratio, or ICR: typically 125% for basic rate taxpayers and limited companies, 145% for higher rate taxpayers borrowing in a personal name. The interest is calculated at a stress rate, not always the pay rate. On fixes shorter than five years lenders typically use the higher of the pay rate plus 2% and a floor around 5.5%. On five year fixes many use the pay rate itself. This calculator stresses at the higher of your entered rate and 5.5%, which is a reasonable midpoint. Alongside the rental test, the loan is capped at 75% of the property value with most lenders. Whichever cap is lower is your real limit. The full explanation with worked examples is in our guide to how lenders stress test buy to let affordability.