How to Measure Toilet Rough-In
Part of our Toilets & Bidets guides.
Rough-in is the distance from the finished wall to the center of the drain (the floor bolts). It decides which toilets fit.
| Time | 5 minutes |
|---|---|
| Difficulty | Easy |
| Tools | Tape measure |
Step by step
- Find the bolts. Locate the floor bolt caps at the base of the toilet.
- Measure from the wall. Measure from the finished wall (not baseboard) to the center of the bolts.
- Round. About 10, 12 or 14 inches; most US homes are 12.
- Check clearances. Also measure side clearance (15 in from center to wall is a common minimum) and front clearance.
Tips & common mistakes
- Measure from the wall behind the toilet, not the baseboard.
- With no toilet installed, measure to the drain center.
Measuring without the old toilet
If the old toilet is already removed, measure from the finished wall to the center of the drain opening. In new construction before drywall, add the thickness of drywall and any tile you'll install.
Common rough-in sizes
| Rough-in | Where you see it |
|---|---|
| 12 in | Most US homes; widest toilet selection |
| 10 in | Older homes, small bathrooms, some condos |
| 14 in | Some older homes; fewer toilet options |
Other clearances to measure
- Side clearance: codes commonly require at least 15 inches from the toilet's centerline to a wall or fixture.
- Front clearance: commonly at least 21 inches of clear space in front.
- Supply valve location: one-piece skirted toilets have specific inlet positions; VEVOR suggests placing the inlet valve about 15-20 cm (6-8 in) from the floor on the side wall for one model.
Odd measurements
An 11-inch measurement usually indicates a 12-inch rough-in with thick tile or wainscoting; a 13-inch measurement may be a 12-inch with an offset. When in doubt, choose the smaller rough-in toilet: it will leave a small gap behind it but will fit.
Frequently asked questions
What if I measure 11 inches?
That's usually a 12-inch rough-in with a thick wall finish; check the toilet's specs or use a 10-inch model.
Does rough-in affect bidet seats?
No, bidet seats depend on bowl shape and bolt spacing, not rough-in.
Can I convert a 10-inch rough-in to 12 inches?
It requires moving the drain, which is a plumbing job.
What is an offset flange?
A flange that shifts the drain connection slightly, used to adjust rough-in by an inch or two.
Do one-piece toilets come in 10-inch rough-in?
Yes, VEVOR offers a 10-inch rough-in one-piece model.