Dimensions / Building materials / Toilets / One-piece toilet
A one-piece toilet casts the tank and bowl as one seamless piece. One-pieces from Kohler, TOTO, American Standard and Swiss Madison run 27 to 29-3/4 in long, 14-3/8 to 20-1/2 in wide and 24 to 31-3/16 in tall, and are usually lower than the two-piece of the same family (Kohler Cimarron 28-13/16 in against 30-3/4 in). They take a 12 in (305 mm) rough-in like two-pieces, with a 10 in model here and there (Swiss Madison Ivy), and ship whole: TOTO’s UltraMax II is 99 lb in one carton, Swiss Madison’s 89.21 to 107.93 lb net. Comfort-height rims are 16-1/8 to 16-1/2 in; ADA measures 17–19 in to the top of the seat.
| Length range | Rough-in | Shipping weight (TOTO UltraMax II) |
|---|---|---|
| 27–29-3/4in | 12in305 mm | 99lb |
Sources: Kohler, TOTO. Checked October 2026.
A 12 in rough-in one-piece on a drain exactly 12 in out, the room measured under the UPC and a 6.0 L single flush are filled in; change the rough-in, what you measured, the code or the flush.
Rough-ins and carrier depths are the makers’ printed minimums; clearances are the model plumbing codes, which a local code may change.
A 12 in rough-in toilet needs at least 12 in (305 mm) from the finished wall to the centre of the flange (American Standard, TOTO); you measured exactly 12 in, so the tank sits where the drawing shows it.
TOTO sets the flange at a nominal 12 in so the tank keeps its gap to the wall.
UPC 402.5 asks for at least 15 in (381 mm) from the toilet’s centreline to a side wall or obstruction and 24 in (610 mm) clear in front of it; you have 15 in and 25 in.
Washington’s UPC: 24 in clear in front, 21 in inside dwelling units.
The US federal limit for a tank toilet is 6.0 L (1.6 gpf) a flush (10 CFR 430.32). This toilet uses 6 L a flush.
American Standard’s one-piece 2034 uses 1.6 gpf (6.0 L): within the federal limit, over WaterSense.
Selling one-piece toilets? Photograph the toilet from the side and in its carton, mark length, width, height, rim height and the carton size and weight in SizeMarker, and send the picture with your quote.
Mark a photoHeight is to the top of the tank. Swiss Madison does not say whether its bowl height is to the rim or the seat; TOTO figures are read from its drawing.
| Model | Length | Width | Height | Rim or bowl height |
|---|---|---|---|---|
| Kohler San Raphael K-3722Elongated, 12 in rough-in | 29 in (737 mm) | 20-1/2 in (521 mm) | 24 in (610 mm) | 15 in (381 mm) |
| Kohler Santa Rosa K-3810Compact elongated, 12 in | 27-3/4 in (705 mm) | 18-3/4 in (476 mm) | 28-3/16 in (716 mm) | 16-1/2 in |
| Kohler Cimarron K-3828Elongated, 12 in | 29-5/16 in (745 mm) | 18-15/16 in (481 mm) | 28-13/16 in (732 mm) | 16-1/2 in |
| American Standard Champion 4 2034Elongated, 12 in, 1.6 gpf | 29-3/4 in (756 mm) | 17-3/4 in (451 mm) | 29-1/2 in (749 mm) | 16-1/2 in |
| TOTO UltraMax IIThis page | 28-3/8 in (720 mm) | 16-5/8 in (423 mm) | 28-3/4 in (731 mm) | 16-1/8 in (410 mm); seat 17-1/4 in (438 mm) |
| Swiss Madison St. TropezElongated, 12 in, 1.1 / 1.6 gpf | 27 in | 15-1/8 in | 31-3/16 in | 16 in |
| Swiss Madison IvyElongated, 10 in rough-in | 27-3/8 in | 14-3/8 in | 28-1/8 in | 15.5 in |
| Swiss Madison HugoElongated, 12 in | 27-3/16 in | 14-15/16 in | 28-15/16 in | 15.5 in |
Sources: Kohler · Kohler · Kohler · American Standard · TOTO · Swiss Madison · Swiss Madison · Swiss Madison
| Item | Figure |
|---|---|
| One castingKohler; Swiss Madison | Tank and bowl integrated into one seamless piece, with no tank-to-bowl joint to seal or clean |
| Ships wholeTOTO; Swiss Madison | UltraMax II 99 lb in one 32 × 20 in carton; Swiss Madison 89.21, 92.51 and 107.93 lb net; the heaviest two-piece part, TOTO’s Drake II bowl, is 57.3 lb |
| Lower, usuallySame family (our comparison) | Kohler Cimarron 28-13/16 against 30-3/4 in (1-15/16 in lower); Champion 4 29-1/2 against 31-3/16 in (1-11/16 in lower); TOTO 28-3/4 against 30 in. Not always: Swiss Madison’s St. Tropez is 31-3/16 in |
| Skirted trapwayKohler; Swiss Madison | Common on one-pieces, but Kohler’s Corbelle is a skirted two-piece, so a skirt alone does not mark a one-piece |
| Compact elongatedKohler Santa Rosa | An elongated seat in the space of a round-front bowl: 27-3/4 in long |
| Setting the flangeTOTO | At a nominal 12 in (305 mm) so the tank keeps its gap to the wall; allow for any baseboard |
Sources: Kohler · Swiss Madison · TOTO · Swiss Madison · Swiss Madison · TOTO · Kohler · Kohler · American Standard · American Standard · Kohler · Kohler · TOTO
Makers print the rim; ADA measures to the top of the seat, which adds the seat’s thickness.
| Item | Figure |
|---|---|
| Standard rimKohler | 14-1/2 in (Wellworth Classic), 15 in (San Raphael) |
| Comfort-height rimKohler; American Standard; TOTO | 16-1/2 in (Kohler Comfort Height, American Standard); 16-1/8 in (TOTO Universal Height) |
| With the seatTOTO drawings | UltraMax II 17-1/4 in over a 16-1/8 in rim |
| ADA, public toiletsADA 604.4 | 17–19 in (430–485 mm) to the top of the seat |
| ADA, dwelling unitsADA 604.4 exception | 15–19 in (380–485 mm) to the top of the seat |
| RoomIPC 405.3.1; UPC 402.5 in Washington | 15 in from the centreline to each side; in front 21 in (IPC) or 24 in (UPC), 21 in in dwelling units |
| Flush limits10 CFR 430.32; WaterSense; NPC 2025; Approved Document G | US 6.0 L (1.6 gpf); WaterSense 4.8 L (1.28 gpf) effective; Canadian homes 4.8 L single; England 4.5 L single |
Sources: Kohler · TOTO · Kohler · American Standard · TOTO · US Department of Justice · ICC · Washington State Legislature · govinfo · EPA WaterSense · National Research Council Canada · UK government
27 to 29-3/4 in long, 14-3/8 to 20-1/2 in wide and 24 to 31-3/16 in tall in the Kohler, TOTO, American Standard and Swiss Madison sheets; TOTO’s UltraMax II is 28-3/8 in long and 28-3/4 in tall.
Usually lower, not shorter: in the same family the one-piece is 1-11/16 to 1-15/16 in lower (American Standard Champion 4, Kohler Cimarron), and the lengths overlap. Kohler’s Santa Rosa fits an elongated seat into 27-3/4 in.
It ships in one carton: 99 lb for TOTO’s UltraMax II, 89.21 to 107.93 lb net for Swiss Madison’s. A two-piece splits the weight; TOTO’s Drake II bowl alone is 57.3 lb.
12 in (305 mm) for most, from the finished wall to the flange centre. TOTO advises setting the flange at a nominal 12 in to keep the gap behind the tank, and Swiss Madison makes the Ivy for a 10 in drain.
The rim is 16-1/2 in on Kohler and American Standard models and 16-1/8 in on TOTO’s; with its seat, TOTO’s UltraMax II comes to 17-1/4 in, inside ADA’s 17–19 in to the top of the seat.
No. Most one-pieces have a skirted base that hides the trapway, but Kohler’s Corbelle is a skirted two-piece.
A buyer of one-pieces asks for the overall length, width and height, the rough-in, the rim height and the seat height with your seat, the flush volume and how it is certified, and, because the toilet ships whole, the carton size and gross weight per carton. Mark those on a photo of your own toilet with SizeMarker, like the picture at the top, and share one card in WhatsApp or WeChat.
