Free tools/Buy to Let Mortgage Calculator UK
Buy to Let Mortgage Calculator UK
Estimate the maximum buy-to-let loan your rent can support at a chosen stress rate and ICR, plus monthly payments and LTV. Rates are your inputs - not live lender quotes.
Cash deposit £62,500
Typical lender stress rates often sit around 5-6%
Max loan at ICR / stress
£209,455
Binding loan (min of LTV & ICR)
£187,500
Requested £187,500
LTV on binding loan
75.0%
Monthly payment
£703
Interest-only at pay rate
ICR at stress rate
140%
Passes target
Rental cover vs stress ICR
£1,509
Annual rent minus (stressed interest × ICR target)
- Stress rate 5.5% with ICR target 125%
- Interest-only monthly payment uses pay rate on the binding loan
- Max loan is capped by ICR at the stress rate, then by purchase LTV
- Illustrative only - lenders apply their own criteria
How this BTL mortgage calculator works
UK buy-to-let affordability is usually rent-led. Lenders stress the interest rate, then check that annual rent covers a multiple of that stressed interest (the interest coverage ratio). This tool takes your monthly rent, purchase price, deposit, pay rate and stress assumptions, then shows the max loan that still clears your ICR target and the binding loan after LTV.
For a deeper walkthrough of the inputs lenders care about, read our buy to let mortgage calculator guide and the interest coverage ratio explainer.
Frequently asked questions
- How do lenders use ICR for buy-to-let?
- Most UK BTL lenders compare annual rent to stressed mortgage interest and require a minimum interest coverage ratio - often 125% for basic-rate borrowers and around 145% for higher-rate. Exact rules vary by lender and product.
- Is this the same as a lender decision in principle?
- No. This calculator is illustrative. Lenders also look at credit, portfolio criteria, valuation, and their own stress rates. Use it to sense-check a deal before speaking to a broker.
- Interest-only or repayment?
- Many BTL loans are interest-only. Switch to repayment if you are modelling a capital-and-interest product - the monthly payment will be higher for the same loan.
Related
Illustrative only - not mortgage, tax or financial advice. Figures depend on your lender, tax status and circumstances. Always check with a qualified adviser before acting.