Quick answer
A toilet flange, called a closet flange in plumbing codes, is the round fitting fastened to the top of a toilet drain pipe and the floor that holds the closet bolts, supports the toilet and gives the wax ring or gasket a flat face to seal against.
If the flange cracks, rusts or sits too low, the toilet rocks and the seal fails, which shows up as water or sewer odor at the base.
Quick facts
The key facts about Toilet Flange, with sources:
- Code name
- Closet ring or closet flange 1
- Diameter
- About 7 inches across (2025 California Plumbing Code) 1
- Drain size
- Usually fits a 3-inch or 4-inch drain pipe 3
- Bolt slots
- At the 3 o’clock and 9 o’clock positions 3
- Common rough-in
- 12 inches from finished wall to flange center (one maker’s toilet) 4
- Materials
- Copper alloy, cast iron, ABS, PVC and other approved types 1
Key takeaways
- The flange is the hidden fitting under the toilet that ties it to the drain and the floor.
- California’s code and one flange maker both say the flange should sit on top of the finished floor, not below it.
- A low, broken or loose flange is a common cause of a rocking toilet and a failed wax seal.
- Match the flange material to the pipe: PVC to PVC, ABS to ABS, cast iron to cast iron.
- Pulling and resetting a toilet can be permit-exempt, but replacing the drain fitting may not be.
A ring that does three jobs
A toilet flange is hidden once the toilet is in place, because it sits under the bowl, glued, caulked or screwed onto the end of the drain pipe that comes up through the floor. Its flat rim spreads out over the floor and gets screwed down into the subfloor.
That small ring has three jobs: it connects the toilet outlet (the horn, the short spout molded into the bottom of the bowl) to the drain line, it anchors the toilet because the two closet bolts that hold the bowl down slide into slots in its rim, and it gives the wax ring or rubber gasket a firm, level face to press against.
Plumbing codes call it a closet ring or closet flange, because the old trade term for a toilet is a water closet. The 2025 California Plumbing Code says closet flanges must be designed and secured to support the fixture connected to them 1. So it is a structural part, not just a pipe fitting.
How the flange holds the seal
Every flush follows the same path through the flange:
- Toilet bowl outlet (horn)
- Wax ring or gasket, squeezed flat
- Toilet flange face
- Drain pipe below the floor
- Drain-waste-vent system
The toilet’s weight and the closet bolts squeeze the seal between the bowl and the flange.
American Standard’s instructions have you set the bowl with a rocking motion until it seats fully on the wax ring and flange, then tighten the nuts in turn, without overtightening 4.
If the flange sits too low, the seal is never squeezed enough. If the flange is loose, the toilet can move and break the seal.
Oatey makes the same point: a flange below the floor cannot compress the wax ring properly, and an unanchored flange can shift and break the seal 3.
Which toilet flange types fit which drain pipes
| Type | How it attaches | Where it fits |
|---|---|---|
| PVC or ABS flange | Solvent cemented to matching plastic pipe 3 | Most newer homes with plastic drains |
| Plastic flange with stainless steel ring | Cemented to the pipe; metal rim resists bending | Oatey suggests stainless ring models for damp areas such as basements 3 |
| Cast iron flange | Caulked or otherwise joined to cast iron pipe | Older homes; caulked flanges must be at least ¼ inch thick and 2 inches deep under California’s code 1 |
| Inside-pipe or replacement flange | Fits inside the existing pipe with a rubber gasket | Repairs where the old flange broke off 3 |
| Offset flange | Shifts the outlet sideways | One maker says up to 2 inches for a misaligned drain 3; check your local code before using one |
| Repair ring and spacer kit | Screws over a broken rim or stacks on a low flange | Fixes a damaged flange or raises one left low by new flooring 3 |
Example: checking a flange before setting a new toilet
A worked example using the dimensions printed in one American Standard toilet’s instructions 4 and Oatey’s flange guidance 3. The measured values are illustrative; the targets come from the sources.
| Check | Target from source | Example reading | Result |
|---|---|---|---|
| Wall to flange center (rough-in) | 12 inches minimum for this model 4 | 12 inches | Fits |
| Closet bolt spacing | About 6 inches apart, parallel to wall 4 | 6 inches | Fits |
| Bolt slot position | 3 o’clock and 9 o’clock 3 | Slots at 3 and 9 | Fits |
| Flange height | On top of the finished floor 3 | About ¼ inch below new tile | Too low: use a spacer kit or thicker ring 3 |
| Anchoring | Screws through the floor into the subfloor 3 | Two screws loose | Re-anchor before setting |
| Side clearance | At least 15 inches from toilet center to a side wall (2015 UPC, WA) 2 | 16 inches | Meets |
In this example, the new tile floor left the flange below grade. That single number decides the repair: raise the flange with a spacer, or use a thicker seal. Fixing it now costs far less than a slow leak into the subfloor.
How to find your flange and tell what it is made of
With the toilet in place, you cannot see the flange. You can see signs of it: the two bolt caps at the base of the bowl sit over the closet bolts, and those bolts rise out of the flange slots.
Measure from the finished wall (not the baseboard) to the center of those bolts to get your rough-in 4.
With the toilet pulled, the flange is the round rim around the drain hole. Look at three things. What is it made of: white PVC, black ABS, cast iron, or plastic with a metal ring?
Is the rim whole, or are the bolt slots cracked or torn? Does it sit on top of the floor, flush with it, or below it?
On a plumber’s invoice, flange work shows up as "closet flange repair," "flange replacement" or as part of a toilet reset. If the drain pipe under it is rotted cast iron, it may turn into a drain repair.
What a sound flange does for you
Sound, well-set flange
Broken, loose or low flange
- Toilet rocks, which breaks the seal over time 3.
- Water seeps into the subfloor where you cannot see it.
- Sewer odor around the base.
- Snapped bolt slots let the bolts pull free.
What a flange cannot fix
A new flange cannot fix a rotted subfloor: if the plywood or planking around the drain has gone soft from a slow leak, the flange screws have nothing solid to bite into, and the toilet will rock again within weeks.
The damaged section of subfloor has to be cut out and replaced before any flange goes back on.
It also cannot fix a drain problem. A toilet that clogs often, or gurgles when another fixture drains, points to the vent system or the drain line, not the flange. And a flange will not change your rough-in.
If your toilet needs 12 inches and the drain is 10 inches from the wall, you need a toilet made for that rough-in, an offset flange where your code allows it, or a pipe change.
What makes flange repair cost more or less
We do not print prices, because a fair number needs dated local quotes, but the pattern is consistent: the flange itself is an inexpensive part, and what moves the bill is what the plumber finds once the toilet is lifted off the floor.
The main cost drivers are: the pipe material (a cast iron flange is harder to remove than a plastic one); whether a repair ring can fix it or the flange must be cut out.
Whether the drain pipe is cracked; whether the subfloor is rotted; whether the floor is concrete, which needs masonry anchors 3; and whether new tile left the flange low.
Our plumbing cost guide explains how plumbers price small repairs.
Lifespan depends on the material and how well the flange was anchored, and we found no national lifespan figure we could verify. A flange in a damp basement may corrode sooner, which is why one maker steers buyers to stainless steel rings there 3.
How a flange gets replaced or repaired
This is the order Oatey’s project guide uses for a plastic flange, plus the reset steps from American Standard’s toilet instructions 34. Many homeowners hire this out.
- Close the toilet supply valve, flush, and sponge out the remaining water 4.
- Disconnect the supply line, unbolt and lift off the toilet, and plug the drain opening to keep sewer gas out 4.
- Scrape away the old wax and inspect the flange, the screws and the floor around it.
- For a cracked rim, a repair ring may be enough. For a broken or wrong flange, cut the pipe to height, chamfer and deburr it, and dry-fit the new flange 3.
- Set the bolt slots at 3 and 9 o’clock and mark the position 3.
- Prime and cement a PVC or ABS flange, push it down with a twist, and hold it about 30 seconds 3.
- Screw the flange through the finished floor into the subfloor with corrosion-resistant screws, or use concrete anchors on a slab 3.
- Install new closet bolts and a new wax ring or gasket; never reuse the old wax 3.
- Set the toilet, tighten the nuts in turn without overtightening, reconnect the water and check for leaks 4.
Measure the floor height first
If you are tiling or adding a floor, check the flange height before the toilet goes back. Oatey says a flange that sits flush or below the floor needs a spacer kit or a thicker wax ring 3.
How to keep a flange from failing
- Fix a rocking toilet right away; movement is what breaks the seal 3.
- Do not overtighten the closet bolt nuts; American Standard warns the base can be damaged 4.
- Replace the wax ring every time the toilet comes off the floor 3.
- Check the flange height whenever you change flooring.
- Watch for soft or stained flooring at the base, an early sign the seal has failed.
Warning signs and when to call a plumber
- The toilet rocks or shifts when you sit on it.
- Water appears around the base after flushing.
- Sewer odor near the toilet that cleaning does not remove.
- Flooring around the toilet is soft, stained or lifting.
- A ceiling stain directly below an upstairs toilet.
- A bolt spins freely or pulls up out of its slot.
Keep the drain plugged and ventilated
An open toilet drain lets sewer gas into the room. American Standard’s instructions say to plug the floor waste opening while the toilet is off 4.
Wear gloves, ventilate the room, and do not leave the drain open overnight. If you smell strong sewer gas you cannot trace, leave the room and call a plumber.
Call a plumber when the drain pipe is cast iron, the flange is set in concrete, the subfloor feels soft, or you see a stain on the ceiling below. Those jobs can grow into leak repair or floor work.
What the plumbing code requires of a closet flange
Flange rules (2025 California Plumbing Code, §402.6, based on the UPC): toilet-to-drain connections must use approved copper alloy, hard lead, ABS, PVC or iron flanges, bolted with an approved gasket, washer or setting compound.
The bottom of the flange must sit on top of the finished floor. Closet flanges are about 7 inches across, and caulked-on flanges must be at least ¼ inch thick and 2 inches deep.
Fasteners must be copper alloy, copper or another equally corrosion-resistant material 1.
Clearances (2015 UPC as amended by Washington, §402.5): no toilet may be set closer than 15 inches from its center to a side wall, or 30 inches center to center from another toilet. Clear space in front is 24 inches, or 21 inches in dwelling units 2.
Permits (2018 IRC text as published by Idaho Falls): removing and reinstalling a toilet is exempt from a permit, as long as the repair does not replace or rearrange valves, pipes or fixtures 6. Cutting out and replacing a drain fitting may count as new work.
Codes differ by state and city. States using the IPC have their own section numbers. Check the code your jurisdiction adopted before you start. Rules checked 2026-10-12.
Flange vs. other parts at the toilet base
| Part | What it does | How a failure shows up |
|---|---|---|
| Toilet flange | Joins drain to toilet and anchors it 1 | Rocking toilet, broken bolt slots |
| Wax ring | Seals the bowl outlet to the flange 3 | Water or odor at the base |
| Closet bolts | Hold the bowl down through the flange 4 | Loose toilet, spinning nut |
| Flapper | Seals the tank, not the floor | Running toilet, not a base leak |
Flange myths that lead to leaking toilets
- Myth The flange should be flush with or below the floor.
- Reality California’s code and Oatey both say it goes on top of the finished floor 13.
- Myth Two stacked wax rings fix a low flange.
- Reality Oatey does not recommend stacking two wax seals; it suggests a jumbo or extra-thick ring or a spacer kit 5.
- Myth Caulk around the base will stop a rocking toilet.
- Reality Caulk hides movement; the fix is a sound, anchored flange and a level floor.
- Myth Any flange fits any pipe.
- Reality Match the material to the pipe, and use approved transition cement for mixed materials 3.
- Myth Tighter bolts make a better seal.
- Reality American Standard warns that overtightening can damage the base 4.
How your local code changes the job
The rule book changes at the state line: California and Washington base their plumbing codes on the Uniform Plumbing Code, which spells out flange materials and setting in §402.6 12.
Most other states base theirs on the International Plumbing Code, with different section numbers and local amendments.
Permit rules vary too: the IRC exemption for resetting a toilet is published by Idaho Falls 6, but your city may treat a flange replacement as new work.
Ask your building department, or have a licensed plumber pull the permit.
When to repair the flange, replace it or call a plumber
A cracked rim on an otherwise sound plastic flange is often a repair-ring job, and a flange left low by new flooring usually needs a spacer, while a broken flange on cast iron, a rotted subfloor or a drain set in concrete calls for a plumber.
The table below matches each finding to the fix that usually solves it.
Next step: if the toilet rocks, stop using it as soon as you can, pop off the plastic bolt caps and check whether the nuts are loose or the bolts spin, because a loose nut is a five-minute fix while a spinning bolt usually means the slot in the flange beneath it has torn.
- If Flange sits below new flooring
- Then Spacer kit or thicker seal 3
- If Bolt slot cracked, flange otherwise sound
- Then Repair ring over the old flange 3
- If Flange broken off inside the pipe
- Then Inside-pipe replacement flange 3
- If Subfloor soft or ceiling stained below
- Then Call a plumber; floor repair first
Source: [3]
Questions about Toilet Flange
Can a broken toilet flange be repaired instead of replaced?
Often, yes. When only a bolt slot or part of the rim is cracked and the flange is still glued solidly to the pipe, Oatey sells repair rings that screw down over the old rim and give the bolts a new hold.
A flange that has broken off inside the pipe can take an inside-pipe replacement flange that seals with a rubber gasket, so the pipe does not have to be cut out.
Rotted subfloor or cracked cast iron under the flange needs a plumber.
Should a toilet flange be flush with the floor?
No, it should sit on top of the finished floor. The 2025 California Plumbing Code says the bottom of the flange must be set on top of the finished floor, and Oatey says the same. A flange below the floor cannot compress the wax ring properly, which leads to leaks.
How do I know if my toilet flange is broken?
A rocking toilet, water at the base, or sewer odor are the usual signs. To confirm, pull the toilet and look. Cracked bolt slots, a rim that has split, a flange that moves when you push it, or rust eating through a metal ring all mean it needs repair or replacement.
Can you replace a toilet flange yourself?
On plastic pipe, many homeowners can, following the maker’s steps: cut, dry-fit, cement, and screw it to the subfloor. Cast iron, concrete slabs and rotted subfloors are harder. Check whether your city requires a permit, because replacing a drain fitting may count as new work.
What size is a toilet flange?
Most fit a 3-inch or 4-inch drain pipe, and the rim is about 7 inches across under the 2025 California Plumbing Code. Buy a flange that matches both the pipe size and the material. Some flanges fit over the pipe and some fit inside it.
What is toilet rough-in?
Rough-in is the distance from the finished wall to the center of the toilet flange. Measure it to the closet bolts. Twelve inches is common; one American Standard model calls for 12 inches minimum. Buy a toilet made for your rough-in rather than forcing the wrong one to fit.
What if my toilet flange is too low?
Raise it or use a thicker seal. Oatey sells flange spacer kits for a low flange and recommends a jumbo or extra-thick wax ring instead of stacking two regular rings. If the flange is far below a new floor, a plumber may cut the pipe and set a new flange.
Which way should toilet flange slots face?
The bolt slots should sit at the 3 o’clock and 9 o’clock positions, which Oatey says to mark during the dry fit. That puts the two closet bolts side by side; American Standard’s instructions set them about 6 inches apart and parallel to the wall behind the toilet.
Do I need a permit to replace a toilet flange?
It depends on your city. Under 2018 IRC text published by Idaho Falls, removing and reinstalling a toilet is exempt as long as no pipes, valves or fixtures are replaced or rearranged. Replacing the flange on the drain pipe may count as new work. Ask your local building department.
Sources
- 2025 California Plumbing Code (Title 24, Part 5) §402.6 Flanged Fixture Connections, as published by GoCodeBook, retrieved .
- Washington State Building Code Council, WSR 17-04-089 amending WAC 51-56 (2015 Uniform Plumbing Code), retrieved .
- Oatey, How to Install a Toilet Flange (manufacturer project guide), retrieved .
- American Standard, Cadet 1.6 GPF Pressure-Assisted Toilet installation instructions (730479-100), retrieved .
- Oatey, Toilet Gaskets and Bolts (manufacturer product and FAQ page), retrieved .
- City of Idaho Falls, ID, Work Exempt from a Permit (2018 IRC text), retrieved .
Expert review
Written by the HyrePlumber Research team. Not yet reviewed by an outside expert. We say so rather than imply a review that has not happened; see our editorial policy.
How the numbers were checked: Flange materials, setting height, diameter, thickness and fastener rules are from the 2025 California Plumbing Code §402.6 (third-party copy, checked against section text). Clearances are from the 2015 UPC as amended by Washington.
Installation steps, slot orientation, spacer and stacking guidance are from Oatey’s project guide (single maker, labeled). Rough-in and bolt spacing are from one American Standard installation sheet. Permit exemption from 2018 IRC text published by Idaho Falls. Example readings are illustrative. No prices.
Suggest a correction. We fix errors and say what changed.