Hotel Room Block Calculator
How many hotel rooms to block for an event's travelling guests — from the guest count, sharing and the share who actually book — with the room-nights, the cost, and what you would owe under an attrition clause if fewer book than planned.
Out-of-town guests over the average per room gives the rooms needed if everyone booked; the pickup rate — the share who use the block rather than staying elsewhere — cuts it, usually to 60 to 80%.
How the hotel room block calculator works
Out-of-town guests over the average per room gives the rooms needed if everyone booked; the pickup rate — the share who use the block rather than staying elsewhere — cuts it, usually to 60 to 80%. That is the block to reserve. The attrition clause is the catch: if pickup falls below the contracted share, you pay for the empty rooms. The page shows the block, the room-nights and the exposure if bookings disappoint.
Formula: rooms = ⌈guests / per room × pickup⌉; room-nights = rooms × nights; attrition owed = (contracted − actual) × rate × nights
Worked examples
| Inputs | Rooms to block | Note |
|---|---|---|
| 80 guests, two nights, 70% pickup | 32 | 32 rooms |
| Everyone books | 45 | 45 rooms |
| A poor turnout | 32 | attrition bites |
FAQFrequently asked questions
What is a room block?
A set of rooms a hotel holds at a negotiated rate for an event's guests, released to the public at a cut-off date. It guarantees availability and a rate; it can also guarantee a bill.
What is attrition?
The clause that makes you pay for rooms in the block that go unbooked beyond an allowance — commonly 10 to 20%. A block of 40 with 20% attrition means you pay for at least 32.
What pickup should I assume?
Sixty to eighty per cent for a wedding or conference with a good rate; lower when guests have points to use elsewhere or the hotel is dear. Ask the hotel what similar events achieved.
Should I block fewer rooms?
Block what you expect at the poor end and negotiate a courtesy block — no attrition — for the rest. Running out of rooms is a nuisance; paying for empty ones is a bill.
What about guests per room?
Couples share, singles do not. One and a half to two is typical for a wedding; closer to one for a business conference.
Where these figures come from
- US FDA Food Code — food service guidance — holding and service context behind catering quantities
- UK Food Standards Agency — the UK food regulator
Last checked: September 2026. Portion and spacing figures are standard catering and event-industry conventions, stated on each page.