Overbooking Calculator

Some guests always cancel late or never show up, so a full book rarely means a full hotel. This tool tells you how many extra reservations to accept so you fill those rooms without walking too many guests, for tonight and for the next 14 nights.

Saves automatically in your browserNo sign-upFreeExact probability model, not a rule of thumb

1Tonight's numbers

Rooms you can sell, what is booked, and how often guests cancel or fail to show. Use your PMS history for the same day of week and season.

Sellable rooms, after rooms out of order
Confirmed bookings for tonight right now
Share of bookings cancelled from now to arrival
Share of remaining bookings that never arrive
ADR: average daily rate, before tax
Parking, restaurant, bar, resort fee
Cleaning, laundry, amenities. Use 0 for revenue only

2Cost of walking a guest

"Walking" a guest means sending someone with a confirmed booking to another hotel because you are full. List every cost of doing it once; the lines add up.

Cost itemAmount ($)
Total cost per walked guest

Tip: "future business at risk" is the profit you expect to lose because some walked guests never book again. A common estimate is the chance they don't return times what they would spend over the next few years.

3Your risk appetite

The best average result sometimes means walking a guest now and then. If your brand standards say that should be rare, set a cap.

For example 10% means about one night in ten
Results update as you type.

Tonight's recommendation

Based on the numbers above. "Expected" means the average over many nights like this one.

Expected net value by overbooking level

Net value = profit from rooms filled minus the cost of guests walked. The orange line is the chance of walking at least one guest.

Recommended level

Every level compared

Overbook byBooking limitGuests expected to arriveExpected empty roomsExpected walked guestsChance of walking anyoneExpected net valueGain vs no overbooking

Green row: recommended. The booking limit is rooms available plus the overbooking level: stop selling when bookings reach it.

414-night planner

One row per night. Type rooms available and bookings on the books; leave the rate columns blank to use the rates from step 1, or enter a night's own rate (for example a holiday or a big event). Revenue, walk cost and risk appetite come from steps 1 to 3.

NightRooms availableOn the booksCancel % (optional)No-show % (optional) Overbook byBooking limitWhat to doChance of walking anyoneGain vs no overbooking

CSV columns: date, rooms_available, on_the_books, cancel_pct, no_show_pct. The last two can be left blank. Up to 14 nights.

How it's calculated

Show-up chance. Each booking turns into an arriving guest with probability p = (1 - cancellation rate) × (1 - no-show rate). Guests are assumed to decide independently of each other.

Arrivals. If you accept L bookings (the booking limit = rooms available C + overbooking level k), the number who arrive, S, follows a binomial distribution with L trials and chance p. The tool works out the full distribution exactly (in log space so large hotels don't overflow). Above 3,000 bookings it switches to a normal approximation with a continuity correction, which is accurate at that size.

For each level:

Expected empty rooms   = E[max(C - S, 0)]
Expected walked guests = E[max(S - C, 0)]
Chance of walking any  = P(S > C)
Value of a filled room = room rate + extras - servicing cost
Expected net value     = value of a filled room × E[min(S, C)] - walk cost × E[walked]

Recommendation. The level with the highest expected net value. With a risk cap, only levels whose chance of walking anyone is at or below the cap are considered. Levels are tested from 0 up to well past the point where extra bookings stop paying.

Assumptions and limits. The model assumes you will sell up to the booking limit (overbooking only matters when demand is strong enough). It does not model walk-ins, early departures, stay-overs that extend, or guests on multi-night stays affecting the next night; no-show fees you collect are not counted, which makes it slightly cautious. Cancellations and no-shows often run together in groups (a storm, a cancelled concert), which this model treats as independent, so on unusual nights a lower cap is wise. Rates are best taken from at least 8 weeks of history for the same day of week and booking channel.

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