Building materials · Reference
A standard toilet uses a 12 in (305 mm) rough-in. Elongated bowls run about 29-31 in (737-787 mm) front-to-back and round-front about 27-28 in (686-711 mm); seat height is ~15 in standard or 17-19 in for ADA.
Toilets are measured by overall length (front to back) × width × height, plus the rough-in from the finished wall to the floor-bolt centerline.
| Dimension | Round-front | Elongated |
|---|---|---|
| Overall length (front to back) | 27-1/2 in (699 mm) | 29-9/16 in (751 mm) |
| Overall width | ~15-18 in (381-457 mm) | 18-1/16 in (459 mm) |
| Overall height (to tank top) | ~28-30 in (711-762 mm) | 30-3/8 in (772 mm) |
| Rough-in (standard) | 12 in (305 mm) | 12 in (305 mm) |
Source: Kohler — Highline Arc K-78279 spec sheet (2020)
| Height class | Seat height | Typical use |
|---|---|---|
| Standard height | 14-15 in (356-381 mm) | Most common residential; easier for children |
| Comfort / chair height | ~16-17 in (406-432 mm) | Easier to sit down and stand up |
| ADA-compliant | 17-19 in (432-483 mm) | Required accessible seat height (ADA 604.4) |
Source: D&G Flooring — Toilet Dimensions Guide (2026)
| Clearance | IPC 405.3.1 minimum | ADA 604 minimum |
|---|---|---|
| Centerline to side wall / obstruction | 15 in (381 mm) | 16-18 in (406-457 mm) fixed |
| Center-to-center to adjacent fixture | 30 in (762 mm) | — |
| Clear space in front of bowl | 21 in (533 mm) | — |
| Clear / compartment width | 30 in (762 mm) | 60 in (1525 mm) |
| Clear / compartment depth | 60 in (1524 mm) floor-mounted | 56 in (1422 mm) from rear wall |
Source: ICC — IPC 405.3.1 Clearance of plumbing fixtures (2018)
A spec table only helps if the buyer reads it. Many don't — shoppers routinely try to judge a product's size straight from the images, and wrong size or fit is the most-cited reason things get returned. The fix is to mark the real dimensions on the photo itself, where the buyer is already looking.
SizeMarker snaps dimension lines to the toilet's edges and exports at Amazon or Alibaba size, so the measurement is accurate and legible — not a guess typed over the picture. That answers the size question up front and cuts pre-sale questions and size-driven returns.
Related: Building material spec diagram maker · Product spec sheet maker · Best tools to add dimensions to product photos · Ecommerce returns & size statistics
The standard rough-in is 12 in (305 mm) from the finished wall to the center of the floor bolts (waste outlet). Older or tight layouts may use 10 in (254 mm) or 14 in (356 mm) rough-ins.
Elongated bowls are about 2 in longer front to back — roughly 29-31 in (737-787 mm) overall vs 27-28 in (686-711 mm) for round-front — giving more seating room. Round-front models save space in small bathrooms.
Standard-height bowls seat about 14-15 in (356-381 mm) off the floor. Comfort/chair-height and ADA-compliant bowls sit at 17-19 in (432-483 mm), which is easier to sit down on and stand up from.
The IPC requires at least 15 in (381 mm) from the toilet centerline to any side wall, 21 in (533 mm) of clear space in front, and 30 in (762 mm) center-to-center between fixtures. ADA requires a 60 in (1525 mm) wide clear floor space.
A standard toilet is about 14-20 in (356-508 mm) wide, with most models around 15-18 in. Overall height to the top of the tank is typically 28-31 in (711-787 mm).
Every figure on this page is traced to a named source, linked under each table. Standard sizes come from published standards and established industry references; where a size is a typical range or varies by manufacturer, we say so. Sizes vary by region, model and revision — treat these as the standard reference, and confirm the exact spec of the item you are selling.
Mark accurate dimensions and specs on your product photos in minutes. Free to start.
Start free · 30 credits on sign-up