Guides / Bathroom · Published 2026-10-28

Toilet rough-in: 12″ is standard, check before you buy

The toilet number nobody checks: 12″.

Rough-in is the distance from the finished wall (not the baseboard) to the centre of the drain, and it decides which toilet fits. 12″ (305 mm) is standard, but older homes also have 10″ and 14″, so measure to the closet bolts before you specify. Wall-hung toilets usually need a 2×6 wall for the in-wall carrier, and you still need 15″ from centreline to the side wall and 21″ clear in front.

Toilet rough-in: 12″ is standard, check before you buy, drawing
Toilet rough-in: 12″ is standard, check before you buy, cheat sheet

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