Measure from the finished wall (not the baseboard) to the center of the bolt caps at the toilet’s base. 12" is the usual rough-in; 10" and 14" turn up in older homes and small bathrooms.
How far is it from the wall to the bolt caps?
Measure from the finished wall, not the baseboard, to the center of a bolt cap at the base. With the toilet off, measure to the center of the drain.
Your rough-in
10" rough-in
The new toilet needs a 10" rough-in. Each toilet is made for at least its own rough-in, so a 12" model won’t fit.
On the package: 10 in. rough-in
Available on Amazon
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Start overYour rough-in
12" rough-in
The most common rough-in today.
On the package: 12 in. rough-in
Available on Amazon
See also
Start overYour rough-in
14" rough-in
Found mostly in older homes. A 14" toilet fits. A 12" one fits too but sits about 2" farther from the wall.
On the package: 14 in. rough-in
Available on Amazon
See also
Start overYour rough-in
Measure again
Rough-ins come out close to 10", 12" or 14". Check you went from the finished wall, not the baseboard, to the center of the bolt or drain.
See also
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A new toilet has to match the rough-in you measure.
How to measure
- Start at the finished wall itself, the tile or drywall. Baseboard and molding stick out from it.
- With the toilet in place, run the tape to the center of one of the bolt caps on either side of the base.
- With the toilet off, measure to the center of the drain opening and its flange, not to the near edge.
- Expect a number close to 10", 12" or 14". Anything else is worth measuring a second time.
Why it has to match
A toilet is designed for a minimum rough-in: a 10" model needs at least 10" from the finished wall to the center of its outlet, and a 12" model at least 12". A 12" toilet won’t fit a 10" rough-in. On a 14" rough-in it fits but sits about 2" farther from the wall. Moving the drain to change the rough-in means opening up the floor.
When your rough-in isn’t 12"
- A conversion kit: some skirted toilets adapt from 12" to 10" or 14" with their maker’s own kit. Kohler lists K-5383 (10") and K-5381 (14") for models such as Corbelle, and TOTO sells 10" and 14" Unifit rough-ins for select skirted toilets.
- A toilet made for your rough-in: makers sell 10" and 14" models; the spec sheet states the rough-in.
- An offset flange: it replaces the flange and moves the toilet’s connection up to 2" forward, back or sideways.
Replacing the flange too?
Toilet flange size