Buy-to-Let Mortgage Calculator

Buy-to-let lenders base the loan on the rent, not your salary. Enter the rent and rates to see the most you can borrow, your interest-only payment and your yield.

Rates checked 1 November 2026.

Most buy-to-let lenders want 25%.
Rental cover (ICR) the lender uses
Letting fees, insurance, repairs, service charge.

Monthly interest-only payment

£937.50

The rent covers the lender test. You could borrow up to about £261,818.

Loan

£225,000

Loan to value

75.0%

Max loan from rent

£261,818

Rent needed for this loan

£1,289

Gross yield

6.00%

Yearly cash flow before tax

£4,350

How lenders work out a buy-to-let loan

Lenders use an interest cover ratio (ICR). The rent must cover the mortgage interest at a stress rate by 125% or 145%.

  • 125% usually applies to limited companies and basic-rate taxpayers.
  • 145% usually applies to higher and additional-rate taxpayers.
  • The stress rate is often 5.5% or the pay rate plus 2%. Five-year fixes are often tested at the pay rate.

Formula: maximum loan = yearly rent / ICR / stress rate. With £1,500 a month rent, a 125% ICR and a 5.5% stress rate, the maximum loan is about £261,818.

Deposit

Most buy-to-let mortgages need a 25% deposit. Some lenders go to 80% LTV at higher rates.

Costs to plan for

  • Stamp duty with the 5% surcharge. Use our stamp duty calculator.
  • Lender fees, often £995 to £1,999 or a percentage of the loan.
  • Letting agent fees, typically 10% to 15% of rent plus VAT for full management.
  • Landlord insurance, gas safety, EICR and EPC certificates, repairs and empty periods.

Frequently asked questions

How much rent do I need for a buy-to-let mortgage?

For a £200,000 loan at a 5.5% stress rate and 125% ICR, the rent must be at least about £1,146 a month. At 145% it is about £1,329.

Are buy-to-let mortgages interest only?

Most are, which keeps payments low. You repay the loan when you sell or refinance.

Can I get a buy-to-let mortgage through a limited company?

Yes. Many landlords buy through an SPV limited company, which often gets the 125% ICR.

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This calculator gives an estimate for guidance only. It is not financial or tax advice. Check the figures with your solicitor, mortgage broker or HMRC before you commit.