Holiday Let Calculator UK: How to Run the Numbers Before You Buy

Start with realistic booking assumptions

A simple annual occupancy percentage is rarely enough for a UK holiday let. Demand is seasonal, and the same property can earn very different weekly rates in school holidays, shoulder months and quiet winter periods. Split the year into high, mid and low season. Enter a weekly rate for each period, then enter the number of weeks you think could be booked in each period.

For example, an illustrative coastal cottage might assume 10 high-season weeks at GBP 1,650, 14 mid-season weeks at GBP 1,050 and 10 low-season weeks at GBP 650. That does not mean the property will achieve those figures. It simply makes the revenue assumption visible, so you can challenge each part and compare it with listings, agent estimates and your own risk appetite.

Separate guest cleaning fees from owner cleaning cost

Cleaning is easy to understate. Some owners see the guest cleaning fee and assume it offsets the cleaner, laundry and changeover cost. In practice, the fee charged to guests may be lower than the amount paid to the cleaning team, especially for larger cottages, hot tub properties and remote locations. A calculator should show the cleaning margin or loss instead of hiding it inside total costs.

A useful assumption is one clean per booked week. That is still simplified because short breaks can increase changeovers, but it is a sensible starting point for pre-purchase screening. If your strategy depends on frequent weekend stays, add a more cautious cleaning cost or include extra annual cleaning in other costs.

Include the costs that make holiday lets different

Holiday lets are operational businesses as much as property investments. Common costs include platform fees, booking fees, agency or management fees, utilities, broadband, insurance, maintenance, repairs, linen, waste, compliance checks, rates or council tax, service charges and replacement furniture. If there is a hot tub, spa or sauna, maintenance and energy costs need their own line.

A maintenance reserve is helpful because repairs rarely arrive in neat annual amounts. The calculator can apply a percentage of booking revenue, such as 5%, as a simple allowance. This is not a prediction; it is a buffer that stops the base case from assuming every year is unusually smooth.

Model finance separately

Net operating income before mortgage is the property result before finance. Keeping it separate helps you compare properties with different deposit sizes and mortgage structures. A deal might have strong operating profit but weak cashflow after a high-rate repayment mortgage. Another might be acceptable only with interest-only finance, which creates a different risk profile.

For interest-only finance, annual mortgage cost is estimated as mortgage amount multiplied by interest rate. For repayment finance, the payment formula includes principal repayment over the term. Neither is a mortgage quote. Treat it as an illustrative scenario until a qualified broker or lender confirms real options.

Use break-even occupancy as a safety check

Break-even occupancy asks how much revenue, or how many booked weeks, are needed to cover operating costs and mortgage cost. This is often more useful than a single return figure. If the property needs very high occupancy just to avoid losing cash, the downside may be uncomfortable even if the optimistic case looks attractive.

You can improve the test by running a worst case. Reduce rates, reduce booked weeks and increase costs. If the worst case is painful but survivable, the opportunity may be worth more research. If a small change turns the result negative, the deal may need a lower purchase price, more deposit, lower management costs or a different strategy.

Before you rely on the scenario

Treat the numbers as a decision screen, not a decision in themselves. A useful holiday-let model should help you decide what to research next: which costs need quotes, which revenue assumptions need evidence, which finance terms need broker confirmation and which legal points need a solicitor. The output is strongest when each assumption has a source, even if that source is only an agent estimate, comparable listing review or supplier quote at the early stage.

Keep a simple evidence file for the property. Save comparable listings, agent income estimates, cleaner quotes, management fee schedules, insurance indications, service charge details, utility assumptions, mortgage illustrations and notes from calls. When the calculator shows a strong result, the evidence file helps you test whether that strength is real. When it shows a weak result, it helps you see which assumption would need to change before the property is worth more time.

Finally, run at least three versions of the deal. The base case should reflect your honest current view. The downside case should reduce revenue and increase costs enough to feel uncomfortable but plausible. The upside case can show what happens if the property performs well, but it should not be the only case used to justify an offer. A deal that survives a cautious downside is usually easier to own than one that needs every assumption to land perfectly.

If the scenario changes materially after one quote, one fee schedule or one mortgage rate update, that is useful information. It means the margin of safety is thin and the purchase needs more evidence before you spend money on surveys or legal work. The best early analysis makes uncertainty visible while there is still time to negotiate, pause or compare another property.

Use the guide with your own numbers

The next step is to turn the assumptions into a scenario for the actual property you are considering. Start with the free holiday-let calculator, compare the model in the premium spreadsheet, or request a practical property review if you want a structured second look.

This tool is for educational and illustrative purposes only and does not constitute financial, mortgage, tax, investment, or legal advice.

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