Toilet Rough-In Guide

How to measure rough-in

Rough-in is the distance from the finished wall behind the toilet to the center of the two closet bolts (the bolts holding the bowl to the floor flange) — not to the flange itself, and not from the baseboard. Measure along the floor, not the wall. Most US residential toilets are built for a 12″ rough-in. 10″ and 14″ exist for tight bathrooms or older construction, but they cost more and come in far fewer styles, so confirm your actual measurement before assuming you need one.

One-piece vs. two-piece

A two-piece toilet ships as a separate tank and bowl, bolted together on site — it’s the more common, generally less expensive option, and individual parts (just the tank, just the bowl) can sometimes be replaced without swapping the whole fixture. A one-piece toilet is a single fused unit — fewer seams means fewer places to leak or trap grime, and a lower profile, but the whole unit gets replaced if either half fails.

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Round vs. elongated bowls

Elongated bowls are about 2″ longer front-to-back than round bowls. That extra length is generally considered more comfortable and is the ADA-referenced shape for accessible installs, but it needs more clearance in front of the bowl — check your local code’s minimum clearance before committing in a tight powder room. Round bowls are the space-saving option for small half-baths.

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Flush rating and trapway

MaP (Maximum Performance) scores tell you how many grams of waste a toilet clears in one flush during independent lab testing — higher is better, and most modern residential toilets score well above what a household actually needs. A fully glazed trapway (the S-curve inside the base) resists buildup better than a rough cast one, which matters more for long-term cleaning than day-to-day flush power.