Start from the house (free account) or from your own drawing. Letting a house to travellers in Japan, the floor of its rooms sets how many guests it may take, and each way of letting counts the floor differently. This article counts it for a synthetic single-storey 4LDK of 150 m², with the same tool your AI calls over MCP. Every number below comes from that run.
What the laws ask
From e-Gov:
- A private lodging (住宅宿泊事業, minpaku): at least 3.3 m² of room a guest (厚生労働省関係住宅宿泊事業法施行規則). The room is every part the guests have to themselves, their kitchen, bath, toilet, washroom and corridors too, but not closets or tokonoma, measured to the inner faces of the walls (住宅宿泊事業法施行要領, the national guidance, as revised on 24 December 2024). What they share with a host who lives there is not theirs.
- A simple lodging (簡易宿所: a guest house or hostel, licensed): guest rooms of 33 m² in all, or 3.3 m² a guest when it takes fewer than ten (旅館業法施行令, article 1, paragraph 2).
- An inn or hotel (旅館・ホテル営業): each guest room at least 7 m², 9 m² with a bed in it (the same article, paragraph 1).
Given the way of letting and the rooms, check_space with lodging returns the rooms’ floor, how many guests it allows, what the guests planned need, and for an inn each room’s minimum.
1. As a private lodging
| The guests have | Floor | Guests |
|---|---|---|
| The whole house: tatami room, bedrooms 1–3, living and dining room, kitchen, bath, washroom, toilet, corridor and entrance hall (not the tokonoma or closets) | 129.06 m² | 39 |
| The tatami room and bedrooms 1–3, the host living there and sharing the rest | 47.52 m² | 14 |
A party of ten needs 33 m², well within either way. The tokonoma (1.8 m²) and the two closets never count. The floor sets the most; the beds and futons there are, and the rules of the house, set how many actually sleep. The floor check (check_space) finds no issues, and from the front door a person reaches every room.
2. As a simple lodging
The four guest rooms come to 47.52 m², 33 m² or more, so the floor does not limit the guests: twelve, or more. Under 33 m², 3.3 m² a guest would be asked. What limits a guest house is elsewhere: the local ordinance (toilets and washbasins for the guests), the fire code and the building code.
3. As an inn
| Room | Floor | Minimum | |
|---|---|---|---|
| Tatami room | 12.96 m² | 7 m² | enough |
| Bedroom 1 (beds) | 12.96 m² | 9 m² | enough |
| Bedroom 2 (a bed) | 8.64 m² | 9 m² | short |
| Bedroom 3 (beds) | 12.96 m² | 9 m² | enough |
Bedroom 2 with its bed is under 9 m²; laid with futons instead of a bed, it would need 7 m².
4. How to use these numbers
- They compare floor areas with the law’s figures. They are not a notification or a licence: the health centre decides how a room is measured (whether a room’s own bath or toilet counts, for example).
- Draw each part the law may leave out (closets, tokonoma, and for a private lodging the parts shared with a host) as a zone of its own, and list only the rooms that count.
- The 180-night limit of a private lodging, local ordinances (areas and days), the fire code (fire alarms, the occupant load), the building code and the number of toilets are not checked.