Well, in simple terms, room inventory is basically a calculation:
The number of rooms a hotel has MINUS the amount of rooms sold
= the number of rooms available for a particular day
But wait. Does that mean every single room in the hotel? The answer is a resounding No. With room inventory, hotels must only include in their calculation the number of rooms available for reservation. For example, a 100-room hotel in Charleroi (Belgium) may be redecorating 25 of its rooms on the third floor, meaning that only 75 per cent of the total rooms at the hotel must be included in the room inventory sum.
The importance of room inventory cannot be stressed enough. After all, every hotel and motel in the world is in business to make money, and the majority of revenue comes from selling rooms. The frequency of carrying out a room inventory procedure is, of course, entirely up to each individual hotel or chain. But, it is advisable to do it at least once a week, and some hotels even carry out a room inventory procedure on a daily basis, as this can help enormously when keeping track of finance (profit and loss) and setting prices for rooms and suites.