Buy to let calculator
Work out your deposit, stamp duty, buy-to-let mortgage payments on both interest-only and repayment, monthly cash flow and whether the rent passes a lender's stress test — before you make an offer.
The purchase
The mortgage
Lender stress test
£656/mo
Most common for landlords
£899/mo
Over 25 years
£294/mo
Rent minus costs and interest
6.60%
Annual rent ÷ price
Passes the rental stress test
At 145% interest cover and a 5.5% stress rate, a lender wants rent of at least £997 a month against a £150,000 loan. You have entered £1,100. On this rent the maximum loan would be around £165,517.
Money in, money out
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Analyse a deal freeHow a UK buy-to-let deal is priced
Cash in the deal is more than the deposit. On a £200,000 additional property at 25% down you need £50,000 deposit plus the stamp duty surcharge, legal and survey fees, and any refurbishment. That total is the number your return should be measured against.
The stress test decides your loan. Buy-to-let affordability is not based on your salary; it is based on rent covering interest by 125% to 145% at a notional rate of roughly 5.5%. If the rent falls short, the lender simply reduces the loan, which means you need a bigger deposit than planned.
Interest-only versus repayment changes cash flow dramatically. Interest-only maximises monthly profit and is the standard landlord choice, but the capital is still outstanding at the end of the term. Repayment builds equity every month at the cost of thinner cash flow — compare both above before deciding.
Tax matters after the numbers work. Individual landlords cannot deduct mortgage interest from rental profit; relief is given as a 20% credit instead, which is why higher-rate taxpayers often look at limited company ownership. Speak to an accountant before you structure the purchase.
Buy to let questions
How much deposit do I need for a buy-to-let mortgage?
Most UK buy-to-let lenders want at least 25% deposit, and the best rates usually start at 35-40%. A handful will lend at 20% but with higher rates and fees, which often wipes out the benefit of the smaller deposit.
What is the buy-to-let rental stress test?
Lenders check that the rent covers the mortgage interest by a margin, called interest cover ratio (ICR). Typically 125% for basic-rate taxpayers and 145% for higher-rate taxpayers, tested at a notional rate of around 5.5% (or the pay rate plus 2%) rather than your actual rate. This calculator shows the rent you need to pass.
How much stamp duty do I pay on a buy-to-let?
Additional properties in England and Northern Ireland carry a surcharge on top of standard SDLT rates, applied from the first pound of the purchase price. This calculator estimates it automatically using the current bands.
Should I use an interest-only or repayment buy-to-let mortgage?
Interest-only keeps monthly payments low and maximises cash flow, which is why most landlords use it, but you still owe the full loan at the end of the term. Repayment costs more each month and clears the debt, building equity faster. This calculator shows both side by side.
Is buy-to-let still worth it in the UK?
It depends entirely on the numbers of the individual deal. Higher mortgage rates, the Section 24 restriction on interest relief for individuals and the stamp duty surcharge have squeezed margins, so cash flow now depends on buying at a strong yield rather than relying on capital growth.
Estimates only, based on the figures you enter. Not financial, mortgage or tax advice — see our disclaimer. You may also like the rental yield calculator and the property ROI calculator.