In short
- Toilet or sink: 15 in from center to a side wall, 30 in center to center (IRC P2705.1).
- In front: at least 21 in of clear space (IRC P2705.1).
- Shower: at least 900 sq in, no side under 30 in (IRC P2708.1).
What the code and guidelines say
Code means the International Residential Code 2021 (IRC); local codes can be stricter. NKBA guidelines are recommendations, not law.
| What | Rule | Where it comes from |
|---|---|---|
| Floor area | no minimum | IRC 2021, a bathroom is not habitable space (R202) |
| Toilet or sink to side wall | at least 15 in from its center | IRC 2021, P2705.1 |
| Between toilet and sink | at least 30 in center to center | IRC 2021, P2705.1 |
| Clear space in front | at least 21 in | IRC 2021, P2705.1 |
| Shower | 900 sq in, no side under 30 in | IRC 2021, P2708.1 |
| Ceiling height | at least 6 ft 8 in | IRC 2021, R305.1 |
| Toilet center to wall | 18 in recommended | NKBA, NKBA guideline 20 |
| Shower | 36 × 36 in recommended | NKBA, NKBA shower guideline |
| Average bathroom | No public source yet | we found no survey of room sizes |
Minimum size by code
The International Residential Code does not count a bathroom as habitable space (R202), so the 70 sq ft rule for rooms does not apply. What decides the size is the space around the fixtures.
A toilet, sink or bidet must sit at least 15 in from its center to a side wall or vanity, and at least 30 in center to center from the next fixture. In front of each, leave at least 21 in to any wall, fixture or door (P2705.1). A shower needs at least 900 sq in inside, with no side under 30 in (P2708.1). The ceiling must be at least 6 ft 8 in (R305.1).
Source: International Residential Code 2021, section R202: Definitions (habitable space), International Code Council; International Residential Code 2021, section P2705.1: Fixture spacing, International Code Council; International Residential Code 2021, section P2708.1: Shower compartments, International Code Council; International Residential Code 2021, section R305.1: Minimum ceiling height, International Code Council.
What designers recommend
The National Kitchen & Bath Association recommends more room than the code: 18 in from the center of the toilet to a wall or fixture, 30 in of clear floor in front of each fixture, and a shower of at least 36 × 36 in.
Source: Bathroom Planning Guidelines with Access Standards (guidelines 4, 20 and the shower guideline), National Kitchen & Bath Association.
Plan the bathroom
Once the size works, these pages help you draw the rest: the water and drains, the tile and every wall.
- Bathroom layouts with dimensions you can edit
- Bathroom plumbing layout: water and drains on the plan
- Tile layout planner: floors and shower walls
- Interior elevations: every wall to scale
- Outlet and switch height
About this page · Written by the Squaremetry team. Sources: International Residential Code 2021, section R202: Definitions (habitable space) (International Code Council); International Residential Code 2021, section P2705.1: Fixture spacing (International Code Council); International Residential Code 2021, section P2708.1: Shower compartments (International Code Council); International Residential Code 2021, section R305.1: Minimum ceiling height (International Code Council); Bathroom Planning Guidelines with Access Standards (guidelines 4, 20 and the shower guideline) (National Kitchen & Bath Association). Last checked on September 27, 2026.