Free tool for UK landlords
Looking at a property and wondering whether the rent will support the mortgage? Enter the loan you want and see the monthly rent a lender would need to see, at the interest cover ratio that fits your situation.
Enter the loan you want to see the monthly rent a lender would need to see.
Worked out on an interest-only basis, the way lenders assess buy to let, so the stressed payment is the interest on the loan at the stress rate.
Important, not financial advice: This calculator gives estimates using typical ICR and stress rate rules. Each lender sets its own figures, HMO ratios especially vary, and some allow top-slicing. It does not check loan-to-value or your wider circumstances. Always confirm with the lender and speak to a qualified mortgage adviser.
A buy to let is judged mainly on the rent, not your salary. The lender works out the interest on the loan at a stressed rate set higher than the rate you pay, then asks for rent worth a set margin above it, the interest coverage ratio. In short:
Rent needed = loan × stress rate × ICR ÷ 12
So a bigger loan, a higher stress rate, or a higher ICR all push up the rent you need.
The stress rate is the biggest lever on the rent needed. Many lenders stress a five-year fix at around 5.5% and a two-year fix or variable at 7% or more. Because a lower stress rate means less stressed interest, the same property needs less rent on a five-year fix, which is why landlords reach for one when the rent is tight.
If the realistic market rent is below the figure needed, the usual ways through are to:
To start from the rent instead and see your maximum loan, use the affordability calculator.
Hitting the rent needed is necessary, but lenders also cap the loan at a share of the property value, commonly around 75%, and run credit and property checks. Once you know the rent works, the mortgage comparison tool helps weigh the true cost of competing deals, and the profit and ROI calculator shows what the rent leaves after every cost.
Many high street lenders ask for a minimum income, most commonly around £25,000, though some lenders have no minimum at all. It is usually there for security rather than affordability: if the property sits empty between tenants, the lender wants comfort that you could still cover the mortgage from other income. The size of the loan itself is set by the rent, not your salary, and on a joint application often only one applicant needs to meet the minimum.
Usually at least a 25% deposit, which is a loan of up to around 75% of the value. A few lenders now go to about 80%, a 20% deposit, but the rates tend to be less competitive, so a larger deposit usually opens up the better deals. Whatever loan you take, the rent still has to pass the stress test on it.
No, it has to cover a tougher, made-up figure. The lender does not test the rent against the rate you actually pay. It works out what the interest would be at a stressed rate, set higher than your rate, and then asks for rent worth 125% or more of that. So the rent has to beat a harder number than your real monthly payment, which is why the rent needed here looks higher than the mortgage you would actually pay. That extra cushion is deliberate, there to cover running costs, empty periods and the chance of rates rising.
Some lenders can consider top-slicing, using your spare personal income to bridge a gap. It is worth pausing before relying on it. On an interest-only mortgage, if the rent does not cover the stressed interest, that is not just a hurdle with the lender, it can be a sign the deal itself does not stack up and is worth reconsidering. Where it can make more sense is a capital repayment mortgage aimed at building equity over the long term, where you are knowingly topping up to pay the loan down. This is general information, not advice, so weigh it up with a broker.
A quick reference at a 5.5% stress rate, showing the monthly rent needed at a 125% and a 145% ICR. For an even rougher gut check, landlords often use about £5.50 to £6 of rent per £1,000 of loan, which is roughly a 125% ICR at 5.5%. Use the calculator above for your exact loan and rate.
| Loan | 125% ICR | 145% ICR |
|---|---|---|
| £100,000 | £573 | £665 |
| £150,000 | £859 | £997 |
| £200,000 | £1,146 | £1,329 |
| £250,000 | £1,432 | £1,661 |
A higher rate taxpayer is held to 145%, so needs the larger figure. An HMO at around 165% needs more again.