A room block is the one wedding or event line item where you sign a contract for money other people spend. Done right, it saves your guests 5–15% and earns you free nights. Done blind, an 80% attrition clause can quietly put a four-figure bill on your plate. Here's the whole mechanism, including the three numbers worth negotiating before you sign.
You contract to hold a set number of rooms at a fixed group rate for your event. Guests then book those rooms themselves — by phone or a custom booking link — until the cutoff date, usually 2 to 4 weeks out, when unsold rooms release back to the hotel. You never front the room charges; your exposure is the attrition clause, which we'll get to.
Hotels want blocks because they move predictable group volume, so 10+ room-nights is where negotiation starts. Under 10, most properties offer a courtesy block: rooms held without a contract, a smaller discount, zero attrition risk. For a 60-person wedding where most guests book one night, that's often the smarter ask.
| Block type | Discount off public rate | Comp policy | Attrition floor |
|---|---|---|---|
| Courtesy (5–9 rooms) | 0–10% | Rare | None |
| Wedding / social (10–30 rooms) | 5–15% | 1 per 10 rooms booked | 80% typical |
| Corporate (10–50 rooms) | 5–20% | 1 per 40–50 room-nights | 70–80% |
Two comp structures dominate. Weddings usually earn 1 comp room-night per 10 rooms booked, credited against your master bill or the couple's room. Corporate blocks use 1 per 40–50 room-nights actually picked up. Note the difference: "booked" counts reservations made, "picked up" counts rooms actually occupied. Read which one your contract uses — no-shows can shrink a pickup-based comp in a way a booking-based one ignores.
Attrition is your promise that the block will mostly fill. The contract sets a floor — 80% of contracted room-nights is the market standard — and if pickup lands below it, you owe damages on the shortfall: the group rate times the missed nights, reduced by whatever the hotel resells. The reduction matters. A hotel at 95% occupancy that resold your empty rooms owes you nothing further; a half-empty property in a soft week will bill you the full gap.
Negotiating moves exist. Ask for a lower floor (70%), a shorter review window, or a resell-credit clause that's automatic rather than "at hotel's discretion." Or sidestep the problem: contract for 20 rooms with an option to expand to 30. Hotels expand blocks readily; they rarely forgive attrition.
Here's the whole stack on a typical wedding block. Contracted: 25 rooms × 2 nights = 50 room-nights at $169, a block worth $8,450 at full pickup.
Guests pick up 88%: 44 room-nights ($7,436). Add 12.5% occupancy tax ($929.50) and a $20 resort fee per night ($880), then credit 2 comp nights — 1 per 10 of the 22 rooms picked, worth $338. Net guest spend: $8,907.50. The 80% floor is 40 nights; 44 clears it by 4.
Now the downside. If only 30 nights fill (60% pickup), you're 10 below the floor: up to $1,690 in damages before resale credits. That's the number to stare at before signing, and you can compute your own version — pickup, comps, and attrition exposure together — with the free hotel room block calculator.
Enter rooms, nights, rate, and expected pickup. Get guest spend, comp credits, and your attrition exposure in one pass.
Room Block Calculator →Book 3–9 months out for weddings, earlier if your dates collide with a citywide convention. Size the block from your guest list realistically: a useful rule of thumb is that 40–60% of out-of-town guests actually book inside the block, with the rest using points, third-party deals, or sharing rides from farther out. If 60 guests need rooms and you expect 1.5 per room, a 20-room block over 2 nights is a defensible start — expand later if reservations run hot.
Two practical safeguards beat any formula: set a reminder a week before the cutoff date to chase unbooked guests, and watch whether the hotel's public rate is undercutting your group rate. If it is, guests are quietly drifting out of the block. You can usually get the hotel to match or adjust rather than lose the pickup.
If your pickup falls below the attrition floor in the contract — usually 80% of room-nights — you owe damages on the shortfall, typically the group rate times the missed nights, minus whatever the hotel managed to resell. On a 50-room-night block that fills only 30, the maximum exposure is 10 nights times the rate: $1,690 at $169.
No. Guests book and pay for their own rooms inside the block at the group rate. Your money is at risk only through the attrition clause if the block underfills, and you may leave a deposit or sign a personal guarantee on large contracted blocks.
Usually, by design: group rates run about 5–15% under the publicly available rate for the same dates. The catch is timing — if the hotel's price drops below your group rate after the cutoff, or a third-party site undercuts it, guests drift out of the block and your attrition math suffers.