UK ICR mortgage and buy-to-let stress screening tool. Computes the maximum loan a BTL or HMO rent figure could support from qualifying gross annual rent, the lender's stressed interest rate, and the lender's interest cover ratio (ICR). Optional LTV produces an implied maximum purchase price. Not a mortgage offer.
ICR mortgage calculator and BTL stress test
UK ICR mortgage and buy-to-let stress screening tool. Computes the maximum loan a BTL or HMO rent figure could support from qualifying gross annual rent, the lender's stressed interest rate, and the lender's interest cover ratio (ICR). Optional LTV produces an implied maximum purchase price. Not a mortgage offer.
Inputs
- Gross annual rent (GBP): Qualifying gross annual rent the lender will accept (often AST gross).
- Stress interest rate (percent_per_year): The lender's stressed interest rate, e.g. 6.5%.
- Interest cover ratio (ICR) (percent): The chosen lender scenario's ICR requirement. The PRA does not prescribe one universal percentage by borrower entity.
- Loan-to-value (LTV) (percent): Optional. If supplied, the tool returns an implied maximum purchase price = maxLoan / LTV.
Outputs
- Maximum interest-only loan at stress (GBP)
- Implied maximum price at stated LTV (GBP)
Calculation formula and denominator
Maximum interest-only loan = annual qualifying rent ÷ (stress rate × ICR multiple). The LTV ceiling is tested separately; the lower loan is the binding screen.
How to Use This Calculator
- Enter the gross annual rent you believe the lender will accept (often AST gross).
- Enter the lender's stress interest rate as an annual percentage.
- Enter the ICR requirement (e.g. 125 means 125%).
- The tool returns the maximum interest-only loan computed as: annualRent / (icrMultiple × stressRateAnnual).
- Optionally tick "Show implied maximum price at LTV" and enter an LTV to see the implied purchase price ceiling (loan ÷ LTV). This ignores SDLT, legals, and deposit mix.
Worked example
£12,000 annual rent ÷ (6.5% × 1.25) = £147,692 maximum loan before lender-specific criteria and any LTV cap.
Method and sources
Reviewed: 26 August 2026
- Enter rent supported by evidence.
- Use the lender’s current stress rate and ICR, not a universal borrower-type preset.
- Compare the ICR result with the product LTV ceiling.
Sources
Assumptions and limitations
- A screening estimate, not a mortgage offer.
- Lenders can apply different rent, tax, portfolio and borrower assessments.
