Rough-in: the one number that decides which toilet fits
| Rough-in | Where you find it | What to buy |
|---|---|---|
| 12 inches | Most houses built since the 1960s; the standard | Any standard toilet; the widest choice and the best prices |
| 10 inches | Older houses, small bathrooms, some condos | A 10 inch rough-in model; fewer choices, often 1 to 2 weeks to order |
| 14 inches | Older houses, mostly pre-1960s | A 14 inch model, or a 12 inch with a 2 inch gap behind the tank (it works but looks off) |
Measure to the bolt centers, from the wall itself. If there is a baseboard, measure above it or add its thickness back. If the old toilet has two pairs of bolts, use the back pair. A reading of 11 1/2 or 12 1/2 inches is a 12 inch rough-in with a slightly thick or thin wall finish; anything under 11 inches is a 10, anything over 13 is a 14.
In a remodel, measure from the wall you will have, not the wall you have now. New cement board and tile on the wall behind the toilet can add 3/4 inch or more, which turns a 12 inch rough-in into an 11 1/4. That still fits most 12 inch toilets, but check the model’s spec sheet for the minimum, and tell the plumber the finished wall thickness before the flange is set.
Five checks before you buy
- Bowl shape against the door. An elongated bowl sticks out about 2 inches farther than a round one (roughly 28 to 31 inches from the wall versus 26 to 28). In a tight bathroom, measure from the wall to the door swing or the vanity edge first.
- Clearance. The usual residential code minimum is 15 inches from the toilet’s centerline to a side wall or vanity, and 21 inches of clear floor in front of the bowl. A new toilet in the old spot is normally fine; moving it is what triggers the check.
- Seat height. Standard bowls are about 15 inches to the rim; comfort or chair height is 17 to 19 inches with the seat. Taller is easier on knees, harder for small children.
- Flush volume. The federal maximum is 1.6 gallons per flush; WaterSense models use 1.28 or less, and some places require them. Dual flush gives a lighter option.
- What comes in the box. Many toilets ship without a seat, and some without the wax ring or bolts. Buy the seat, a wax or waxless seal, closet bolts and a braided supply line the same day, so the job does not stop at hour two.
How long it takes
| Job | Typical time | What makes it longer |
|---|---|---|
| Straight swap, same rough-in, good flange | 1 to 3 hours | Seized tank bolts, a stuck shutoff valve |
| Swap plus a new shutoff valve and supply | 2 to 4 hours | Old galvanized or soldered pipe at the wall |
| Swap plus a flange repair or spacer | Half a day | A cracked cast iron flange, rotted subfloor around it |
| Moving the toilet, or a different rough-in | 1 to 3 days plus inspection | Opening the floor, rerouting the drain, a permit |
| Wall-hung toilet | Planned at framing | It needs an in-wall carrier, usually in a 2x6 wall, before the drywall |
Lead time for the toilet itself is usually days: 12 inch two-piece models are stocked almost everywhere. One-piece, skirted, 10 and 14 inch and wall-hung models more often run 1 to 3 weeks, which matters if the bathroom is in a remodel with a fixed date. The rest of the bathroom’s lead times are in bathroom vanity lead times.
What has to be finished first in a remodel
The toilet sits on the finished floor, so it is one of the last fixtures in. The full sequence is in the order of a bathroom remodel; for the toilet, it comes down to this:
| Before the toilet | Why |
|---|---|
| Rough plumbing at the right rough-in | The drain is set to the toilet’s number before the floor goes down |
| Finished floor, tile grouted | The toilet and the flange both sit on it; tiling around a toilet leaves a patch |
| Flange at the finished floor height | The flange should sit on top of the tile, flush to about 1/4 inch above; a flange left below the tile leaks |
| Paint behind the tank | The wall behind a toilet is the hardest one in the house to paint later |
| Shutoff valve with its escutcheon | Set it about 6 inches left of center and 6 to 8 inches up, and replace any old multi-turn valve with a quarter-turn |
The order of the job
- Water off, tank and bowl empty. Close the shutoff, flush, sponge out what is left. If the shutoff will not close, that is the first repair.
- Old toilet out, drain plugged. A rag in the drain keeps sewer gas in and dropped bolts out. Scrape off every bit of the old wax.
- Check the flange. It should be screwed down, uncracked and level with or just above the floor. A repair ring or a spacer is cheap now and impossible later.
- Dry fit. Set the new toilet without the seal to check that it sits flat and clears the wall. A rocking toilet gets shims, not more wax.
- Seal, set, tighten evenly. One set, straight down. Snug the nuts a little at a time, side to side; porcelain cracks when one side is cranked.
- Supply, test, watch. New braided supply line, water on, flush ten times and check the base and the tank bolts with a dry paper towel. Caulk the base afterward if your code or the maker calls for it; many plumbers leave a small gap at the back so a leak shows instead of rotting the floor.
What it costs
A basic two-piece toilet runs about $150 to $350, mid-range one-piece and comfort-height models $300 to $700. A plumber’s straight swap is commonly $150 to $400 in labor, more with a new valve or a flange repair, and many charge to haul the old one away. Where a toilet sits in the whole bathroom budget is in what a bathroom remodel costs, and where it sits in the calendar is in how long a bathroom remodel takes. If the toilet is the last fixture in a bigger job, it is also the first line of the punch list: no rock, no run, no drip at the supply.
Measure the rough-in from the finished wall, buy the parts with the toilet, set it on the finished floor, and test it before the plumber leaves.