Free tool for UK landlords
Work out your monthly cash flow and return on investment after all the costs of a buy to let, including void periods. Figures are before tax, with your deposit worked out for you.
Fill in the fields to see your cash flow calculation
Information, not financial or tax advice. BTL Insight is not a tax adviser. This calculator gives estimates only and the figures shown are before tax. You will pay income tax (personal name) or corporation tax (limited company) on rental profits, and Section 24 restricts mortgage interest relief for personal landlords, both of which reduce your actual returns. Always consult a qualified accountant or tax adviser for figures based on your circumstances.
The Return on Investment (ROI) shows what percentage return you're getting on the actual cash you've put in. This is the figure you should use to compare against other investments like savings accounts or stocks.
For example, if you invested £70,000 total (deposit plus all fees) and make £3,500 profit per year, your annual return is 5%.
This is more useful than just looking at rental income, because it accounts for all your costs and shows the return on your actual money invested, not the property value.
Many landlords only consider the deposit when calculating returns. But your true investment includes all the upfront costs:
On a £200,000 property, these additional costs can easily add £15,000 to £20,000 on top of your £50,000 deposit. That's a 30 to 40% increase in your actual cash invested, which significantly impacts your true return.
Monthly cash flow: What's left in your pocket each month after mortgage and all ongoing costs. Positive cash flow means the property pays for itself.
Annual return: Your yearly profit expressed as a percentage of your total cash invested. Compare this directly to savings accounts, stocks, or other investments to see how your BTL stacks up.
Initial term totals: Shows your total profit over the fixed rate period (2, 3, 5, or 10 years). This helps you understand the real return before you need to remortgage.
When that deal ends, the remortgage and ERC calculator helps you decide whether to switch early or wait, after weighing the early repayment charge.
There's no universal answer, it depends on your goals and alternatives:
Consider the full picture:
To size the borrowing first, use the affordability calculator, and the stamp duty calculator to estimate the tax across the UK.
To keep the result honest and based on numbers you actually know today, this tool deliberately leaves three big things out. Each can make a real difference, so weigh them up for yourself:
In short, this calculator answers one question well: based on today's numbers, what is your before tax cash return? Tax, future house prices and how rents drift over time are left to your own judgement.
Yield and return on investment answer different questions. Rental yield measures the annual rent against the property value, so it tells you how hard the property works regardless of how you paid for it. Return on investment, or cash on cash return, measures your annual profit against the cash you actually put in: the deposit, stamp duty and fees. This calculator focuses on ROI because it reflects the return on your own money once a mortgage is doing some of the work.
Gross yield is the annual rent divided by the property value, times 100. So £12,000 of rent on a £200,000 property is a 6% gross yield. Net yield does the same sum but takes the running costs off the rent first, which gives a more honest picture once management, insurance, maintenance and voids are paid. Net yield is always lower than gross. This tool goes a step further and works out your cash return after the mortgage as well, not just the yield on the property value.
There is no single number, but as a rough guide many landlords look for a gross yield of around 5 to 8% on a standard single let, which usually leaves a smaller net figure once costs are paid. Higher yields are possible on HMOs and in some northern and midlands cities, while London and the south often yield less because prices are high relative to rent. A strong yield on paper still has to pass the lender's stress test and leave positive cash flow, which is what this calculator checks.
This is the effect of the mortgage. Yield is measured against the full property value, but your ROI is measured against just the cash you put in, often around a quarter of the price on a 75% loan. Because the rent works against the whole property while your money only covers the deposit and costs, the percentage return on your cash can be noticeably higher than the yield. The trade off is that borrowing adds interest cost and risk, which the cash flow here already reflects.
For an honest figure, include both the one off purchase costs and the ongoing running costs. Up front that means the deposit, stamp duty, solicitor, broker, valuation and any lender fees, plus safety certificates. Ongoing it means the mortgage, letting or management fees, landlord insurance, maintenance, ground rent and service charge on a leasehold, and an allowance for void periods when the property sits empty. This calculator has a field for each so nothing quietly gets missed. Remember the result is before tax.
Interest only usually gives stronger monthly cash flow, because you pay only the interest and nothing towards the balance, which is why many landlords use it. Repayment costs more each month, but part of that payment chips away at the loan, so you are building equity rather than losing the money. This calculator shows both: switch the repayment type to compare the monthly cash flow, and on repayment it also credits the equity you build over the term.