Portfolio LTV and ICR calculator
Once you hold four or more mortgaged properties, lenders assess the whole portfolio, not just one property. Enter each property to see the aggregate loan to value, the rent weighted interest cover ratio, the maximum borrowing the total rent supports, and your capacity for a top up.
A portfolio landlord, under the Prudential Regulation Authority definition, holds four or more mortgaged buy to let properties, and is assessed on the whole portfolio at once. This calculator models the two ratios at the centre of that assessment: the aggregate loan to value across every property, and the rent weighted interest cover ratio against the total debt. Add a row for each property, enter its value, mortgage balance and monthly rent, and set the stress rate and interest cover. It starts with four rows because that is where portfolio status begins. Everything runs in your browser.
- Total value£0
- Total mortgage balance£0
- Total annual rent£0
- Rent weighted ICR0%
- Max aggregate borrowing (rent)£0
- Capacity for a top up£0
Indicative only. Not financial advice or an offer of finance. Lenders also apply a loan to value cap per property and their own background portfolio criteria.
The two ratios that decide a portfolio case
Portfolio lending turns on two aggregate numbers. The first is the portfolio loan to value: the total of all mortgage balances divided by the total value of all properties. Most portfolio lenders cap this in the region of 75 percent, and a background portfolio above that ceiling can block a new advance even where the property you are buying is modestly geared. The second is the rent weighted interest cover ratio: the total annual rent divided by the total debt stressed at the notional rate. This is the portfolio wide version of the single property stress test, and it tells the lender whether the combined rent covers the combined debt with the required margin.
Reading the borrowing capacity
The maximum aggregate borrowing is the total rent divided by the stress rate and the interest cover ratio, the same formula as a single property applied to the whole book. Your capacity for a top up is that maximum less the debt you already carry. Positive capacity means the rent would support further borrowing, subject to the loan to value cap on each individual property, which is how you plan a capital raise for the next deposit. Negative or zero capacity means the portfolio is already at the limit the rent supports, and the route to more borrowing is more rent, lower balances, or a higher yielding addition. This is the differentiator for portfolio landlords: it models the book the way a lender does, not one property at a time.
For the product and the underwriting expectations, see portfolio mortgages, and for the individual property maths that feeds each row, the buy to let mortgage calculator. If you are restructuring into a company, the limited company mortgage calculator and limited company buy to let mortgages cover the SPV route.
Portfolio calculator: common questions
What is a portfolio landlord?
Under the Prudential Regulation Authority definition, a portfolio landlord is one who holds four or more mortgaged buy to let properties. Once you cross that threshold, lenders assess the whole portfolio, not just the property you are buying or remortgaging. They look at the aggregate loan to value, the total rental income against the total debt, and often ask for a portfolio schedule, a business plan and cash flow. This calculator models the two ratios that sit at the centre of that assessment across every property at once.
How do lenders stress test a whole portfolio?
A portfolio lender tests the aggregate as well as the individual property. It takes the total rent, stresses it at a notional rate and applies an interest cover ratio to the total debt, giving a portfolio wide interest cover. It also looks at the aggregate loan to value across all properties, because a background portfolio geared to the hilt is a risk even when the new property stacks up on its own. If the aggregate loan to value is too high, or the combined rent will not cover the combined debt at the stress rate, the case is declined regardless of how strong the single property looks.
How much can I borrow against my portfolio?
The rent sets a ceiling on the total debt the portfolio can carry: total annual rent divided by the stress rate and the interest cover ratio. The capacity for further borrowing is that ceiling less the debt you already hold. If the ceiling is above your current balances, the difference is headroom you could draw by capital raising, subject to the loan to value cap on each property. If it is below, the portfolio is already stretched on the rent and further borrowing would fail the stress test. The calculator shows both the ceiling and the headroom on your figures.
Does one weak property drag down the portfolio?
It can. Because a portfolio lender looks at the aggregate, a low yielding or highly geared property pulls down the weighted interest cover and lifts the aggregate loan to value for the whole book. Sometimes the fix is to hold that property with a different lender, reduce its balance at the next remortgage, or improve the rent. Modelling the portfolio as a whole, as this tool does, shows you which property is doing the damage and by how much, so you can plan the next remortgage around it rather than discover the problem at underwriting.
Related calculators and finance
Buy to let mortgage calculator
Size the loan on a single property before you add it to the portfolio.
Open →Rental yield calculator
Check the yield on each property that drives the weighted interest cover.
Open →Portfolio mortgages
Finance and criteria for landlords holding four or more mortgaged properties.
Learn more →Restructuring a portfolio?
Send us the schedule and the rents. We model the aggregate loan to value and interest cover across the market and place the facility that releases the most capacity.