What is a hotel room block?
A room block is the contract behind a group hotel stay. This cheat sheet covers how to think about one, what attrition costs, the four stages and what to settle before you sign. The detail is further down.
How to think about it
- It's a contract. The rate, the rooms you commit to and what happens to empty rooms all live in one agreement.
- About 9 rooms is the line. At 9 or more rooms, most hotels move you to their group sales process.
- Courtesy or guaranteed. A courtesy block releases unclaimed rooms at no charge. A guaranteed block gets a better rate because you commit to filling a share of it.
- The rate isn't the whole cost. Attrition, the cutoff date and cancellation terms move the real cost more than the nightly rate.
The math
You pay for the rooms you committed to but didn't fill, times the nights, times the group rate.
Block 30 rooms for 2 nights at $180 with an 80% attrition threshold, and you owe for 24 rooms. Fill 20 and you pay for 4 empty rooms x 2 nights x $180.
$1,440 paid for rooms no one slept in
Illustrative example from Engine's room block guide. Thresholds, cutoff dates and rates vary by hotel contract.
The process
- QuoteSend hotels your dates, room count and location, usually as an RFP. They reply with a group rate.
- ContractThe rate, attrition, cutoff date, deposits and cancellation terms are set in writing.
- PickupTravelers claim rooms with a group code, booking link or rooming list until the cutoff, usually 30 days before arrival.
- Stay and settleThe hotel bills on the payment terms. If you fell short, this is where attrition comes up.
Before you sign
- Size. Adding rooms later at the group rate is usually possible. Shrinking a guaranteed block is a negotiation at best.
- Attrition. Often 80% or more, and it can be negotiated down before you sign.
- Mitigation. The hotel tries to resell your unfilled rooms and credits those sales against your attrition bill. Many contracts leave it out.
- Shrinkage. The right to cut the block by a set share before a deadline, without penalty.
- Master bill. If the company pays, ask for one account for the whole block, and write down whether incidentals go on it.
Courtesy block vs. guaranteed block
| Courtesy block | Guaranteed block | |
|---|---|---|
| If rooms go unused | They go back to the hotel at the cutoff, no charge | You pay for rooms below the attrition threshold |
| Typical size | Smaller groups | Larger groups, where most hotels require a guarantee |
| Rate | Modest, the hotel carries the risk | Stronger, your commitment buys it |
| Best for | Headcounts that might change | Firm rosters: crews, conferences, offsites |
How it works on Engine
Up to eight rooms book on Engine like any other trip. At nine rooms, Engine starts a Groups request, and the Groups team sources hotels, handles the contract and manages the block. Attrition terms are set in each proposal and contract, so review them before you commit.
Questions
How many rooms do you need for a room block?
Most hotels draw the line at about 9 rooms. Below that, it's usually a normal booking. On Engine, a ninth room starts a Groups request.
Does a room block cost money?
Opening one usually doesn't. A courtesy block has no commitment, and a guaranteed block usually takes a deposit that counts toward the final bill. The cost comes later, if you leave committed rooms empty.
What is attrition in a hotel contract?
The share of blocked rooms you promise to fill, often 80% or more. If you fall short, you pay for the rooms nobody slept in, usually at the group rate.
What is a cutoff date?
The date unclaimed rooms go back to the hotel, often about 30 days before arrival. After that, latecomers pay whatever the hotel is charging, if it has rooms at all.
What is the difference between a courtesy block and a guaranteed block?
A courtesy block holds rooms with no penalty if they go unused. A guaranteed block commits you to filling a share of the rooms in exchange for a better rate and terms.
Sources
- Engine, Hotel Room Blocks: How They Work and How to Book One for Your Business, accessed October 30, 2026.
- Engine, Group Hotel Room Blocks, accessed October 30, 2026.