Buy-to-let borrowing calculator
Buy-to-let lenders base the loan mainly on the rent, not your salary. Estimate the most the rent supports, and the deposit that leaves you needing.
How this is calculated
The rent test: the yearly rent must cover the interest at the stress rate by the interest cover ratio. The most the rent supports is the yearly rent divided by the ratio times the stress rate.
The loan to value test: the loan cannot be more than the maximum share of the price.
The lower of the two is the most you could borrow, and the deposit is the price less that loan.
Rates used · 2026/27
| Rent test | rent ÷ (cover ratio × stress rate) |
| Common cover ratios | 125% or 145% |
| Common maximum loan to value | 75% |
| Lender criteria | vary, check before applying |
Last checked July 2026. Source: HMRC and gov.uk.
Worked example
£1,250 a month is £15,000 a year. At a 125% cover ratio and a 5.5% stress rate the rent supports a loan of up to £218,182, but 75% of a £250,000 price caps it at £187,500, so the deposit needed is £62,500.
Common questions
How much can I borrow for buy to let?
Usually the lower of what the rent supports under the lender's rent test and the lender's maximum loan to value, often 75%.
Why do higher rate taxpayers face a higher ratio?
Because mortgage interest only gets basic rate tax relief for individual landlords, so lenders build in a bigger margin.
Does my income matter?
Less than for a home mortgage, but lenders often want a minimum personal income and may use it to top up a weak rent test.
Is it different through a limited company?
Companies are often tested at the lower ratio, because they can deduct mortgage interest in full.