Key takeaways
- The 2021 IRC figures are 15 inches from a toilet's center to a side wall, 21 inches clear in front, and a shower of 900 square inches with a 30-inch minimum dimension.
- These are minimums, not design advice, and designers often recommend more.
- A minimum-size bathroom can still feel tight, so mock it up with tape first.
Enter your measurements to compare them with 2021 International Residential Code (IRC) minimums. This doesn't confirm that a room meets your code. It compares your numbers with named figures, while your local building department decides what applies.
The figures
| Item | 2021 IRC figure | Section |
|---|---|---|
| Toilet, sink or bidet center to side wall or partition | At least 15 in | P2705.1 |
| Between adjacent fixtures, center to center | At least 30 in | P2705.1 |
| Clear space in front | At least 21 in | P2705.1 |
| Shower interior | At least 900 sq in | P2708.1 |
| Shower's smallest finished dimension | At least 30 in | P2708.1 |
| Bathroom ceiling | At least 6 ft 8 in | R305.1 |
| Over a shower | At least 6 ft 8 in over 30 × 30 in at the showerhead | R305.1 |
| Waterproof wall finish at showers and tubs with showerheads | To at least 6 ft above the floor | R307.2 |
The code also calls for ventilation. Section R303.3 allows a window with at least 3 square feet of glazing, half of it openable, or artificial light plus local exhaust to the outdoors. Table M1505.4.4 sets bath fans at 50 cfm intermittent or 20 cfm continuous.
We checked P2705.1 and the start of P2708.1 against the 2024 edition and they match, but we haven't compared the others.
Code minimum or good design?
A room can reach every minimum and still be awkward. The National Kitchen & Bath Association publishes recommendations that are often more generous. They aren't code, and the free PDF is older than its current edition, so treat them as ideas.
For a toilet at exactly 15 inches each side, the compartment is 30 inches wide. Try this before you commit to a layout:
- Mark the fixtures on the floor with painter's tape.
- Walk through it, and open each door with people in the room.
- Check that door swings don't hit fixtures. Shower doors with hinges must open outward under P2708.1.
Checking a shower
Both shower figures must work together:
| Width | Depth | Area | Compared with 900 sq in and 30 in |
|---|---|---|---|
| 30 in | 30 in | 900 sq in | At both figures |
| 28 in | 40 in | 1,120 sq in | Area above, narrow side below |
| 32 in | 32 in | 1,024 sq in | Above both |
| 36 in | 36 in | 1,296 sq in | Above both |
P2708.1 also carries the size up to at least 70 inches above the drain outlet, so measure the finished size. Tile and backer take up space.
Before you start
Moving plumbing or electrical work can need a permit and a licensed professional, depending on your area. In older homes, read about lead and old floors before you demolish anything.
Frequently asked questions
How much room do you need around a toilet?
The 2021 IRC figures are at least 15 inches from center to each side and at least 21 inches clear in front. Many people prefer more.
What's the smallest shower allowed?
Under the 2021 IRC, at least 900 square inches inside, with at least 30 inches as the smallest finished dimension. There are exceptions, so check the full section.
Does this cover accessible bathrooms?
No. Accessibility standards are different and aren't covered by this tool.
Sources
We use primary sources where we can: building codes, federal rules and manufacturer documents. Read our editorial standards.
- 2021 International Residential Code: Chapter 27, Chapter 3
- National Kitchen & Bath Association: Bath Planning Guidelines