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Ducts, pipes & wiring · Bathroom Fixture Clearance Checker

Smallest shower allowed by code

The 2021 IRC asks for 900 sq in inside with no dimension under 30 in, so 30 by 30 in is its smallest square; the 2024 UPC asks for 1,024 sq in and room for a 30 in circle, so 32 by 32 in. Pick your code and enter your own inside dimensions below.

Short answer
2021 IRC: inside area, at least (P2708.1)
900 sq in
2021 IRC: smallest inside dimension, at least
30 in
2021 IRC exception: smallest inside dimension of 25 in allowed where the area is at least
1,300 sq in
2021 IRC: clear width of the access opening, at least (P2708.1.1)
22 in
2021 IRC: clearance in front of the opening, at least (Figure R307.1)
24 in
2024 UPC: finished interior area, at least (408.7)
1,024 sq in
2024 UPC: must hold a circle of
30 in
2024 UPC: unobstructed door opening, at least (408.6)
22 in
2024 UPC: smallest square that meets both (a longer rectangle with a 30 in short side can too)
32 by 32 in

Finished inside dimensions, measured at the height of the top of the threshold and kept up to 70 in above the drain. 30 by 30 in and 32 by 32 in are the smallest squares, not the only shapes that pass. The UPC minimums do not apply to a receptor at least 30 in by 60 in overall. This tool checks rectangular showers only. These are two different codes, not a range: use the one your area has adopted. Dwellings only; accessible (ADA, ICC A117.1) layouts need more room. Local amendments govern.

Your code and your tape

Enter every distance to the finished surface. If the walls are still bare framing, first subtract the thickness of the board and tile still to come: once for a distance to one wall, a shower wall or a curb, twice for a distance between two of them. This tool subtracts nothing for you.

Code your area uses

The International Residential Code and the Uniform Plumbing Code set different minimums. If you do not know which your building department enforces, ask before you set the drain.

Are the distances you are entering finished-surface distances?

Nothing passes until you answer Yes. Every distance is in inches; you can type fractions like 15 1/2.

Toilet or bidet
Check the toilet?

Stand facing the toilet: left and right are your left and right.

in
Measure level, to the nearest finished face of that thing: the tiled or painted wall, the tub rim, the tiled face of the shower wall or curb, the side of the vanity or cabinet, or the nearest edge of the fixture.
in
in
From the front edge of the bowl rim straight out to the nearest wall, fixture or door. If the toilet is not set yet, take that edge from the model’s rough-in sheet: its overall depth from the finished wall behind it.
Lavatory (bathroom sink)
Check the lavatory?

Stand facing the lavatory: left and right are your left and right.

in
Measure level, to the nearest finished face of that thing: the tiled or painted wall, the face of the shower wall, glass panel or door, the bathtub rim, the side of the other vanity or of the cabinet, or the nearest edge of the basin or fixture.
in
in
From the front edge of the lavatory, or of its counter if that sticks out farther, straight out to the nearest wall, fixture or door. If the lavatory is not set yet, take that edge from the model’s rough-in sheet: its overall depth from the finished wall behind it.
Shower (rectangular)
Check the shower?
in
in

Enter the smallest width and depth found between the top of the threshold and 70 in above the drain. Leave out valves, shower heads, soap dishes and grab bars (and shelves under the UPC). A built-in bench is on neither list: measure to its face. Rectangular showers only, not neo-angle, round or curved ones.

in
The narrowest clear width: jamb to jamb, or with a door fully open, from the door to the opposite jamb.
in
From the outside face of the shower at the opening (the curb, or the door when shut, whichever is farther out) straight out to the nearest wall, fixture or other obstruction. The IRC figure gives the 24 in without saying exactly where it starts; this is the stricter reading.
Result
Not checked yetPick your code to see a result.

    Plan view, looking down, one panel per fixture, each to its own scale, drawn from the figures entered. You are standing at the bottom of each panel facing the fixture. Shaded strips are the clear space the code asks for: green where it is met, red where it is not, amber where it is short only on a reading marked “Ask”. The toilet and lavatory outlines are generic, not your model. A distance over 48 in is drawn cut short with a dashed line.

    Rule: 2021 IRC R307.1 or 2024 UPC 402.5 · Tested against 32 worked examples, 1 printed in a published source · How this is worked out →

    Questions people ask

    How much space do you need around a toilet by code?
    Under the 2021 IRC a toilet needs at least 15 in from its centreline to any side wall, partition or vanity, 30 in centre to centre between adjacent fixtures, and 21 in of clearance in front. Under the 2024 UPC the side and centre-to-centre figures are 15 in and 30 in, and the clear space in front is 24 in. Local amendments can change either, and accessible bathrooms need more.
    Is the 15 inches measured from the edge of the toilet or the centre?
    From the centre. Both codes word it as the distance from the centre of the water closet to the side wall, and the IRC figure draws it from the centreline of the bowl. So a single toilet needs a space at least 30 in wide between two walls. This tool checks the distance to the finished wall surface, or to the nearest edge of a vanity, tub or other obstruction. It subtracts nothing for you: if you measure off bare studs, take off the thickness of board and tile still to come before you enter the figure.
    What is the smallest shower allowed by code?
    Under the 2021 IRC a shower compartment needs at least 900 sq in of inside area and no inside dimension under 30 in, so 30 by 30 in is the smallest square. An exception allows a dimension down to 25 in where the area is at least 1,300 sq in. Under the 2024 UPC it needs 1,024 sq in and room for a 30 in circle, so 32 by 32 in is the smallest square, and those two minimums do not apply to a shower receptor at least 30 in by 60 in overall. Both measure the finished interior and want the opening at least 22 in wide. The IRC figure also shows 24 in of clearance in front of the opening; no such figure was found in the UPC.
    Does a toilet have to be 30 inches from the sink?
    Under the 2024 UPC no: its 30 in centre-to-centre rule is between a toilet or bidet and a similar fixture, and a sink or vanity beside the toilet only has to be 15 in from the centreline of the toilet. Under the 2021 IRC the sentence asks for 30 in centre to centre between adjacent fixtures without saying which. This tool reads that as covering a toilet beside a sink, but the figure in the code draws that pair with only the 15 in dimension, so a shortfall there is reported as something to confirm with your inspector, not as a plain fail.
    Do these clearances apply to an accessible (ADA) bathroom?
    No. These are the ordinary minimums for one- and two-family dwellings. Accessible design standards such as the ADA Standards and ICC A117.1 set their own, larger clearances and are not checked by this tool.