How to measure a toilet rough-in
One measurement decides which toilets can be delivered to your bathroom at all. It takes a tape measure and thirty seconds, and most people take it from the wrong place.
By Sawyer V. · · How we research
The short answer
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Quick picks
Tap any row for the full write-up. Prices are checked against Amazon rather than remembered — where we have no verified figure the button says so.
| # | Product | Best for | Renter | Price |
|---|---|---|---|---|
| 1 | No photo yet Colony 3 Two-Piece Round-Front Toilet A two-piece round-front published at a 10 in. rough-in and 1.28 gpf, WaterSense certified. | Older homes and tight bathrooms | Owner-only | |
| 2 | No photo yet Santa Rosa One-Piece Compact Elongated Toilet, 1.28 gpf A one-piece comfort-height at a 12 in. rough-in, 1.28 gpf, 27-3/4 in. deep. | Most bathrooms | Owner-only | |
| 3 |  Cadet PRO Two-Piece Chair Height Elongated Toilet Published at a 10 in. rough-in and 17 in. high with the seat, which is an unusual pair. | An older rough-in with modern seat height | Owner-only |
What a rough-in is
The rough-in is the distance from the finished wall to the center of the drain in the floor. Since the closet bolts sit in a flange centered on that drain, measuring to the bolts measures the rough-in without lifting anything.
It matters because a toilet is built around that distance. Fit a 12 in. toilet to a 10 in. rough-in and the tank hits the wall; fit a 10 in. toilet to a 12 in. rough-in and you are left with a two-inch gap behind it.
The three numbers you will meet
- 12 in. — the standard. Both Kohler one-pieces we cover publish it, and American Standard’s skirted Studio publishes 12 in. as well.
- 10 in. — common in older houses and small bathrooms. The Colony 3, in both bowl shapes, and the Cadet PRO publish 10 in.
- 14 in. — rare, and it exists. No toilet in our catalog publishes a 14 in. rough-in, which is itself the useful fact: if you measure 14, expect a short list.
Measure these three things at once
While the tape is out, take the two measurements that catch people after the toilet arrives:
- Side clearance. From the center of the bolts to the nearest wall, vanity or tub.
- Depth. Published footprints run 27-3/4 in. for Kohler’s Santa Rosa and Memoirs Stately, and 28-9/16 in. for the Adair. That is how far into the room the new toilet will come.
- Supply position. Which side the water line enters, and whether a one-piece tank will cover it.
If the old toilet has already gone
With the toilet removed the measurement is easier and the reference point changes: measure from the finished wall to the center of the floor flange, which is the plastic or metal ring the toilet bolts to. That center is the drain center, and it is the same number you would have taken from the bolts.
While the flange is visible, check two more things. First, that it sits on top of the finished floor rather than below it — a flange buried under new tile is the usual cause of a rocking toilet. Second, that the bolt slots run parallel to the wall, because a flange rotated a few degrees makes a toilet sit askew however carefully you measure.
What you cannot fix with a measurement
A rough-in that reads 11 in. is not a rough-in size — it is usually a 12 in. flange with a baseboard in the way, or a drain that was never set square. Offset flanges exist and they are a plumber’s solution, not a shopping one. Measure twice, and if the number is not near 10, 12 or 14, get the flange looked at before you buy anything.
If you rent
Toilets rate Owner-only on our install rating, and replacing one is the landlord’s work. The measurement is still worth taking: it is the first thing a landlord or plumber will ask, and it is the difference between a same-day swap and a return. What a tenant can change is covered here.
Every pick in full
3 we would buy. Each carries its Renter-Safe Install Rating, the published specs behind it, and the honest gap in what we know.
1. For a 10 in. rough-in
Colony 3 Two-Piece Round-Front Toilet
American Standard · 250DB104.020 · best for older homes and tight bathrooms
A two-piece round-front published at a 10 in. rough-in and 1.28 gpf, WaterSense certified.
A 10 in. rough-in narrows the field sharply. American Standard’s Colony 3 publishes a 10 in. rough-in with a round-front bowl, “1.28 gpf / 4.8 Lpf” and “WATERSENSE CERTIFIED”, on a 3 in. flush valve.
The same model is published in an elongated bowl at the same 10 in. rough-in, which is the rarer and more useful combination. Round against elongated is compared here.
Renter-Safe Install Rating
- Drilling
- None
- Tools
- Not published
- Time to fit
- Not published
- Power
- None
- Reversible on move-out
- No
Why: Replacing a toilet means draining and removing the old one, fitting a new wax ring to the closet flange and reconnecting the supply. It is plumbing work on the property's drainage and is never a tenant's change.
Read from published documentation, not from fitting one. American Standard — Colony 3 round-front 10 in. rough toilet, published flush data and warranty. How the verdict is derived: renter-safe ratings explained.
What’s wrong with it
American Standard publishes that the seat, wax ring and supply lines are not included.
What we can’t tell you
No MaP flush-performance score is published for it.
Published specifications
| Rough-in | 10 in. |
|---|---|
| Bowl shape | Round-front |
| Flush volume | “1.28 gpf / 4.8 Lpf” |
| Water efficiency | “WATERSENSE CERTIFIED” |
| Flush valve | 3 in. |
| Trapway | 2 in. |
| Water surface | 9 in. x 8 in. |
| Type | Two-piece |
| Seat | “Toilet seat, wax ring and supply lines are not included” |
| Warranty | “Limited Lifetime Warranty on Chinaware; 5-Year Warranty on Mechanical Parts; 1-Year Warranty on Seat” |
| Overall dimensions | Not published in the specification table |
| Bowl height | Not published in the specification table |
| MaP rating | Not published |
Source: American Standard — Colony 3 round-front 10 in. rough toilet, published flush data and warranty
#ad We have no verified live price for this one right now, so we are not showing a number. How we’re funded.
2. For the standard 12 in.
Santa Rosa One-Piece Compact Elongated Toilet, 1.28 gpf
Kohler · K-3810 · best for most bathrooms
A one-piece comfort-height at a 12 in. rough-in, 1.28 gpf, 27-3/4 in. deep.
Twelve inches is the modern standard, and it is where the choice opens up. Kohler’s Santa Rosa publishes a 12 in. rough-in, 1.28 gpf through an AquaPiston canister, a 16-1/2 in. rim height and a 27-3/4 in. deep footprint.
Depth is the measurement that matters after the rough-in: nearly 28 in. from the wall is a real amount of a small bathroom.
Renter-Safe Install Rating
- Drilling
- None
- Tools
- Not published
- Time to fit
- Not published
- Power
- None
- Reversible on move-out
- No
Why: Replacing a toilet means removing the old one, seating a new wax ring on the flange and reconnecting the supply. It is work on the property's drainage and never a tenant's change.
Read from published documentation, not from fitting one. Kohler — Santa Rosa K-3810 specification sheet. How the verdict is derived: renter-safe ratings explained.
What’s wrong with it
A one-piece is heavier to carry in and more expensive to replace if the china cracks.
What we can’t tell you
Kohler publishes no MaP score for it.
Published specifications
| Type | One-piece, floor-mount |
|---|---|
| Bowl | Compact elongated — “occupying the same space as a round-front bowl” |
| Height | Comfort Height; 16-1/2 in. from floor to rim on Kohler's drawing |
| Flush | 1.28 gpf (4.8 lpf), AquaPiston canister |
| Trapway | 2-1/8 in. fully glazed |
| Water surface | 11 in. x 8-1/8 in.; rim to water surface 6-1/4 in. |
| Rough-in | 12 in. |
| Footprint | 27-3/4 in. deep, 18-3/4 in. wide, 28-3/16 in. tall |
| Seat | Quiet-Close elongated seat with Quick-Release |
| Standards | EPA WaterSense; ADA when installed to its requirements |
| Warranty | KOHLER Toilets and Seats Limited Warranty — terms are on Kohler's website, not the sheet |
| MaP rating | Not published on the specification sheet |
#ad We have no verified live price for this one right now, so we are not showing a number. How we’re funded.
3. 10 in. rough-in at chair height
Cadet PRO Two-Piece Chair Height Elongated Toilet
American Standard · 609AB001.020 · best for an older rough-in with modern seat height
Published at a 10 in. rough-in and 17 in. high with the seat, which is an unusual pair.
The Cadet PRO publishes “10-in. (254 mm)” rough-in and “17-in. high with seat”, with a “fully glazed 2-1/8 in. trapway” and a “Lifetime on chinaware, 5 years on parts” warranty.
If your measurement comes back at 10 in. and you want comfort height, this is the combination to look for. Comfort height against standard is compared here.
Renter-Safe Install Rating
- Drilling
- None
- Tools
- Not published
- Time to fit
- Not published
- Power
- None
- Reversible on move-out
- No
Why: A full toilet replacement on the property's soil drainage. American Standard ships the wax ring and seat in the box, which makes it easier for an owner and changes nothing for a tenant.
Read from published documentation, not from fitting one. American Standard — Cadet PRO chair height elongated toilet, published height, flush data and contents. How the verdict is derived: renter-safe ratings explained.
What’s wrong with it
Chair height suits most adults and is too tall for small children without a step.
What we can’t tell you
American Standard publishes no MaP rating for it.
Published specifications
| Rough-in | “10-in. (254 mm)” |
|---|---|
| Bowl shape | Elongated |
| Height | “17-in. high with seat” — chair height |
| Flush volume | “1.28 gpf (4.8 LPF)”, WaterSense certified |
| Flush valve | “3-in. flush valve” |
| Trapway | “fully glazed 2-1/8 in. trapway” |
| Included | “Slow-close seat, metal trip lever, color-matched bolt caps, wax ring, EZ-Install Kit” |
| Surface | EverClean antimicrobial surface; PowerWash rim |
| Warranty | “Lifetime on chinaware, 5 years on parts” |
| MaP rating | Not published |
| Availability | Sold out on American Standard's own store at the time of writing |
#ad Price $360.59 as of October 18, 2026. Prices change; Amazon’s listing is the one that counts. How we’re funded.
Where to buy
Everything recommended on this page, in one place. Each link is an Amazon Associates link — we earn a commission at no extra cost to you, and it never decides a pick.
- Check price on Amazon
Colony 3 Two-Piece Round-Front Toilet
American Standard · 250DB104.020 · Renter verdict: Owner-only
- Check price on Amazon
Santa Rosa One-Piece Compact Elongated Toilet, 1.28 gpf
Kohler · K-3810 · Renter verdict: Owner-only
- $360.59View on Amazon
Cadet PRO Two-Piece Chair Height Elongated Toilet
American Standard · 609AB001.020 · Renter verdict: Owner-only
#ad Prices are not shown because we only publish figures we have verified on the day. How we’re funded.
Questions people actually ask
how do you measure a toilet rough-in
Measure from the finished wall behind the tank to the center of the closet bolts at the base of the toilet. Do not measure to the baseboard, and if there are two bolts per side use the rear pair.
what is a standard toilet rough-in
12 inches. Ten inches is common in older homes and 14 inches exists but is rare. Every toilet publishes the rough-in it is built for.
can you fit a 12 inch toilet in a 10 inch rough-in
No. The tank will not clear the wall. Buy a toilet published for a 10 in. rough-in — American Standard publishes the Colony 3 in both bowl shapes and the Cadet PRO at 10 in.
does the baseboard count when measuring a rough-in
No. Measure from the finished wall itself. A baseboard can add half an inch, which is enough to make a standard 12 in. rough-in read as something that does not exist.
Sources
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