A yield calculator is only as honest as its inputs, and most of the ones online ask for two numbers and give a gross figure that flatters every property. This page is for the UK buy-to-let landlord using a rental yield calculator, the one on this site or any other: what it must ask for to produce a net figure, what each input does to the result, how to read the gross and the net side by side, and what the calculator cannot tell you. The calculator on this site is free, computes on the page, and takes the costs a real letting carries.
The two inputs every property yield calculator asks for
Purchase price or current value, and monthly rent. From those any gross yield calculator produces the headline figure: rent times twelve, divided by price, as a percentage. That is a fair comparison between properties and an unfair description of any one of them, because none of the costs are in it yet.
The inputs a net rent yield calculator needs
Letting agent fee as a percentage of rent including VAT, or nothing if you self-manage. Annual insurance. Service charge and ground rent for a leasehold flat. A repairs and maintenance allowance for the year. Void weeks expected between tenancies. The costs of buying: stamp duty, legal fees, survey, initial refurbishment. Each of these lowers the net yield, and a calculator that does not ask for them is not calculating a net yield whatever it calls the result.
Reading gross and net together
The gap between the two figures on the same property tells you how expensive the property is to hold. A flat with a heavy service charge shows a wide gap; a freehold house you manage yourself shows a narrow one. When comparing two properties, compare the net figures and glance at the gap; a high gross with a wide gap is a property that will disappoint.
What the buy to let yield calculator cannot tell you
It cannot tell you the rent you will achieve, whether the tenant will stay, what the roof will cost in year three, or whether the area will grow. It works the arithmetic on the assumptions you give it; the judgement about the assumptions is yours. Use realistic void weeks and a repairs allowance that matches the property's age, and rerun it when the facts change.
Keeping the figure once you own the property
A yield worked before purchase is a forecast. Once the property is let, the rent roll gives you the achieved rent and the actual costs, and the yield becomes a measurement. RentRollDesk Pro, at £9 per month for every property, keeps the rent roll and the saved yield figures per property so the forecast and the measurement can be compared at year end; the free calculator here needs no account at all.
Questions people ask about rental yield calculator UK
Which is the best btl yield calculator?
One that asks for the letting costs and the void weeks and shows gross and net side by side. Any calculator that asks for two numbers is a gross calculator.
Should a buy to let rental yield calculator include the mortgage?
No. Yield is worked before finance so properties compare fairly. The rental income tax calculator here handles the interest and the finance-cost restriction separately.
Why does my rental yield uk calculator result differ from the agent's?
The agent quoted gross on asking rent and asking price. Yours is net on achieved rent with real costs. Yours is the one to plan on.