A half bath, a toilet and a sink, can be as small as 2 ft 6 in × 6 ft 9 in with the two facing each other, 4 ft 3 in × 4 ft 9 in with the toilet facing the door, or 5 ft × 4 ft 3 in side by side, at the building code’s clearances. For the roomier spacing designers use, plan on 3 ft 4 in × 6 ft 9 in, 4 ft 6 in × 5 ft 2 in or 5 ft 8 in × 5 ft. Those sizes hold an elongated toilet, a 24 in vanity and a 30 in door.
How small can a half bath be?
The size depends on where the toilet and the sink go, and on two sets of numbers. The code wants 15 in from the toilet’s or the sink’s centerline to a wall or a fixture beside it, 30 in from one to the other center to center, and 21 in of clear floor in front of each (IRC R307.1, P2705.1). The NKBA suggests 18 in beside a toilet, 20 in from a sink’s center to a wall and 30 in in front. The layout planner found the smallest room for each layout:
| Layout | At the code minimum | At the roomier spacing |
|---|---|---|
| Side by side, one wall | 5 ft × 4 ft 3 in (21.3 sq ft) | 5 ft 8 in × 5 ft (28.3 sq ft) |
| Facing, opposite walls | 2 ft 6 in × 6 ft 9 in (16.9 sq ft) | 3 ft 4 in × 6 ft 9 in (22.5 sq ft) |
| Toilet-room style | 4 ft 3 in × 4 ft 9 in (20.2 sq ft) | 4 ft 6 in × 5 ft 2 in (23.3 sq ft) |
Width × depth, the width along the wall the toilet stands on in the side-by-side and toilet-room layouts. Every room holds an elongated toilet (about 30 in deep), a 24 × 21 in vanity and a 30 in door. In the side-by-side and facing sizes the door can swing in if it opens beside the sink; in the toilet-room sizes it has to swing out or slide.
What sets each size
- Side by side: along the wall, 15 in from the wall to the toilet’s centerline, 30 in on to the sink’s, and 15 in from there to the other wall: 15 + 30 + 15 = 60 in. Out from the wall, the toilet’s 30 in plus 21 in of clear floor is 51 in. With the NKBA’s numbers it’s 18 + 30 + 20 = 68 in along the wall and 30 + 30 = 60 in deep.
- Facing: the room only has to be 2 × 15 = 30 in wide by code, or 40 in for the NKBA’s 20 in beside the sink. Its length is set by the door, not the clearances: the door goes in a side wall between the two fronts, so the gap has to take the 30 in door: 30 + 30 + 21 = 81 in.
- Toilet-room style: the toilet faces the door from the end wall and the vanity stands on a side wall, starting where the toilet ends. The toilet’s 30 in wide clear space has to clear the vanity’s front, which puts its centerline 36 in from the vanity’s wall, and 15 in more (18 for the NKBA) to the other wall makes 51 (54) in. The depth is the toilet’s 30 in, 12 in to the sink’s center and 15 in (20) to the door wall.
A shorter toilet helps everywhere. A compact elongated toilet is about 28 in deep (Kohler Santa Rosa: 27¾ in), and a wall-hung one about 21 in (Kohler Veil), against about 30 in for a standard elongated toilet. The tiniest rooms are on the powder room layouts page.
Will a half bath fit in your space?
“Roomy” means a layout fits with every NKBA number, “Code” that it fits at the code minimum, and “No” that nothing fits with these fixtures and a 30 in door.
| Room | Fits? | Layouts that work |
|---|---|---|
| 2 ft 6 in × 7 ft | Code | Facing |
| 3 × 6 ft | No | A wall-hung toilet and a 24 in door change that |
| 3 × 7 ft | Code | Facing |
| 3 ft 6 in × 7 ft | Roomy | Facing, toilet-room style |
| 4 × 5 ft | No | Too short for facing, too narrow for the others |
| 4 × 6 ft | Code | Facing |
| 4 ft 6 in × 5 ft | Code | Side by side, toilet-room style |
| 4 ft 6 in × 5 ft 6 in | Roomy | All three |
| 5 × 5 ft | Code | Side by side, toilet-room style |
| 5 × 6 ft | Roomy | All three |
Every door position and swing tried in 3 in steps, with an elongated toilet and a 24 × 21 in vanity. Your room in the planner: enter it, set the bath to “None (a half bath)” and see every layout that fits.
Three smallest half baths, drawn to scale
The dashed boxes are the clear spaces in front of each fixture, and the brass line marks the toilet’s centerline.
- Toilet centerline to the side: 18 in
- Clear in front of the toilet: 30 in
- Clear in front of the vanity: 39 in
- Sink centerline to the side: 20 in
Side by side, 5 ft 8 in × 5 ft
Along the 68 in wall: 18 in from the wall to the toilet’s centerline, 18 in on to the vanity, then 12 in to the sink’s center and 20 in from there to the far wall. The toilet and the sink are 30 in apart, center to center, and there’s 30 in in front of the toilet and 39 in in front of the vanity.
- Best for: a door in the wall facing both fixtures.
- At the code minimum: 5 ft × 4 ft 3 in, with the toilet 15 in from the wall and 21 in in front of it.
- Clear in front of the vanity: 30 in
- Sink centerline to the side: 15 in
- Toilet centerline to the side: 15 in
- Clear in front of the toilet: 30 in
Facing, 2 ft 6 in × 6 ft 9 in
The toilet and the vanity face each other from the two 30 in end walls, each centered: 15 in to each side, the code minimum. Between their fronts, 81 − 30 − 21 = 30 in, room for the door in the side wall and 30 in in front of each fixture.
- Best for: a long, narrow space with the door in the middle of a long wall.
- At the roomier spacing: 3 ft 4 in wide, for 20 in beside the sink.
- Toilet centerline to the side: 18 in
- Clear in front of the toilet: 32 in
- Clear in front of the vanity: 33 in
- Sink centerline to the side: 20 in
Toilet-room style, 4 ft 6 in × 5 ft 2 in
The toilet faces the door from the end wall, 18 in from the side wall, and the vanity stands on the other side wall where the toilet ends. There’s 32 in in front of the toilet and 33 in in front of the vanity, and the sink’s center is 20 in from the door wall.
- Best for: a deep room with the door in the short wall, facing the toilet.
- At the code minimum: 4 ft 3 in × 4 ft 9 in, with 27 in in front of the toilet.
Questions people ask
What is the minimum size for a half bath?
By the code’s clearances, about 2 ft 6 in × 6 ft 9 in with the toilet and sink facing each other, 4 ft 3 in × 4 ft 9 in with the toilet facing the door and the sink on a side wall, or 5 ft × 4 ft 3 in with both on one wall. That’s with an elongated toilet, a 24 in vanity and a 30 in door.
Can a half bath be 3 feet wide?
Yes, if the toilet and the sink face each other from the two short walls and the room is at least 6 ft 9 in long, so the door fits in the long wall between them. Side by side or toilet-room style, 3 ft is too narrow.
Is 4 × 5 big enough for a half bath?
Not with an elongated toilet, a 24 in vanity and a 30 in door: none of the three layouts fits. A wall-hung toilet and a small wall-mounted sink change that; see the powder room layouts.
How far apart should a toilet and a sink be?
At least 30 in from the toilet’s center to the sink’s by code, and 15 in from the toilet’s center to the side of a vanity (IRC P2705.1). The NKBA suggests 18 in from the toilet’s center to anything beside it.
Does a half bath door have to swing out?
Not always. In the side-by-side and facing sizes a door that swings in fits if it opens beside the sink rather than the toilet. In the toilet-room sizes it would hit the toilet, so it has to swing out or slide.
Can you add a shower to a half bath?
Only if there’s room: a shower needs at least 900 sq in and 30 in across, plus 24 in in front, which turns it into a 3/4 bath of at least about 5 ft 3 in × 6 ft. See what is a 3/4 bathroom.
Sources
- 2021 International Residential Code, chapter 3 (R307.1 fixture clearances, R305.1 ceiling height) and chapter 27 (P2705.1 fixture spacing, P2708.1 showers), read in Colorado’s adoption without amendments on UpCodes
- Larimer County, Colorado: Figure R307.1 bathroom clearances
- NKBA’s free bath planning guidelines: the roomier spacing (18 in beside a toilet, 20 in beside a sink, 36 in between two sinks, 30 in in front of each fixture, a 36 × 36 in shower, a 32 in door opening, a 36 × 66 in toilet compartment). Its newer, paid editions change some numbers.
- Toilet depths from the wall: Kohler Cimarron round and elongated spec sheets
- Kohler Santa Rosa compact elongated toilet spec sheet: 27¾ in from the wall to the front of the bowl
- Kohler Veil wall-hung toilet spec sheet: 21 in from the finished wall to the front of the bowl
Checked October 19, 2026. Every size and plan was worked out with the BathDraft layout planner; centimeters are converted from inches.