How to Identify Your Toilet Flapper by Brand [2026]

Pop the tank lid to replace a leaking flapper and you’re staring down a hardware-store aisle of red rubber discs that all look roughly the same. How to identify your toilet flapper by brand actually starts inside the tank, not with the old flapper in your hand – Korky’s own compatibility tables match replacement flappers to a toilet’s brand, tank model number, and flush-valve size, not to the color or shape of whatever’s currently bolted in Korky 2-inch compatibility table. Get any one of those three wrong – brand, size, or valve style – and the new flapper either won’t seat or won’t seal, and you’re making a second trip.

This guide walks through where to find the tank’s model number, how to size the flush-valve opening, how to tell a hinged flapper from a canister or tower valve, and what the markings mean specifically for American Standard, Kohler, TOTO, Mansfield, and Glacier Bay toilets.

How to Identify Your Toilet Flapper by Brand: Start With the Tank, Not the Flapper

The most useful identifiers are the brand logo, the tank model number, the flush-valve style, and the flush-valve opening size – in roughly that order of usefulness Korky Toilet Genius. Lift the tank lid, set it aside, and look at the inside tank wall, where manufacturers commonly stamp or print the tank identifier. Korky’s compatibility tables repeatedly reference “models and tank numbers” as the lookup key, and that’s the number to compare against a parts chart – not the brand printed on the bowl or lid Korky 2-inch compatibility table.

A few real examples worth knowing: Korky lists its 2-inch Ultra 2X flapper as compatible with American Standard Cadet tank numbers 4029, 4078, 4083, 4053, and 4650, Kohler Portrait K-4590, Kohler Wellworth K-4620, K-4512, and K-4519, and TOTO Carusoe 706 Korky 2-inch compatibility table. On many toilets the tank number matters more than the bowl number, because the flapper attaches to the tank’s flush valve, not the bowl Korky toilet anatomy. In two-piece toilets the bowl and tank can carry separate numbers, so photograph the tank number specifically before you shop Korky 3-inch compatibility table.

If the tank wall is blank or hard to read, check the underside of the tank lid next – it can carry a brand mark or casting mark, though lids are sometimes swapped between similar toilets, so trust the tank wall first Korky Toilet Genius. And treat the old flapper itself as a clue, not proof: Korky and Home Depot both sell universal replacement flappers by model number, such as Korky’s 2017CM, which may have been installed by a previous owner or plumber after the toilet left the factory Home Depot Korky 2017CM.

Measure the Flush-Valve Opening: 2-Inch vs. 3-Inch

Once you have a tank number (or even without one), the physical opening at the bottom of the tank narrows the search fast. Korky says flappers are commonly sold as either a standard 2-inch or a large 3-inch replacement, and the quickest test is size comparison: an opening about the size of an orange or baseball is a standard 2-inch flush valve, while an opening about the size of a grapefruit or softball is a large 3-inch flush valve Korky flapper size guide.

Age is a rough guide, not a rule. Korky says most toilets made before 2000 use the standard 2-inch flapper, while some toilets made after 2000 use the larger 3-inch size – but there’s real overlap Korky flapper size guide. Specific post-2000 families that take the 3-inch path include American Standard Cadet 3, Kohler Cimarron K-4634, Mansfield Denali 3916, and TOTO Drake ST743, while other American Standard, Kohler, and TOTO tanks stay on the 2-inch table Korky 3-inch compatibility table. If you want the full measuring walkthrough and a chain-adjustment check before you buy anything, see our guide to what size flapper do I need.

Hinged Flapper, Canister, or Tower? Read the Flush-Valve Style

A traditional flapper sits on top of the flush-valve opening, seals the tank when closed, and lifts by chain when the handle is pressed Korky toilet anatomy. A tower or canister flush valve works differently – a vertical canister or tower lifts off a rubber seal instead of a hinged flapper swinging open, and Korky notes that leak is often fixed by replacing just the seal rather than the whole valve Korky toilet anatomy.

This distinction matters because a homeowner shopping for “a flapper” may actually need a flush-valve seal instead, on toilets like Kohler Class Five, Kohler Class Six, American Standard Champion, and Mansfield 210/211 Korky flush-valve seal guide. Korky’s canister-style seal for Kohler Class Five, Kohler Class Six, and American Standard Champion 3 replaces Kohler GP1059291 and American Standard 738651-0070A Korky flush-valve seal guide. For an American Standard Champion 4 or Eljer Titan 4 flush valve, Korky’s seal (part 450) replaces American Standard 7301111-0070A Korky flush-valve seal guide. Kohler also has a handful of specialty shapes worth knowing on sight: Rialto float flapper, hinge flapper, shark-fin flapper, and flush-ball flapper, all signals that a generic 2-inch flapper won’t work Korky Toilet Genius.

Visual ID by Brand: American Standard, Kohler, TOTO, Mansfield, and Glacier Bay

American Standard spans ordinary 2-inch and 3-inch flappers plus Champion-style seals, so the flush valve – not the brand name alone – decides the part. Cadet, Evolution 2 Flowise, Monarch, and Mainstream tanks sit on the 2-inch table; Actifresh, Cadet 3, Cadet 3 Flowise HET, Clean, Edgemere, and Titan Elite sit on the 3-inch table; Champion 4 and Eljer models need the specialty seal path covered above Korky 2-inch table, Korky 3-inch table.

Kohler is visually tricky because some models use ordinary flappers and others use canister-style seals or specialty shapes. Kohler Portrait K-4590 and Wellworth K-4620, K-4512, K-4519 are standard 2-inch flappers; Cimarron K-4634 is a 3-inch flapper; and Kohler’s own Rialto, hinge, shark-fin, flush-ball, and canister-seal variants are separate paths entirely Korky 2-inch table, Korky Toilet Genius.

TOTO tank numbers frequently carry an ST prefix in compatibility lists, like Drake ST743 and EcoDrake 743E, both on the 3-inch table Korky 3-inch compatibility table. TOTO Carusoe 706 sits on the 2-inch table, and Korky also lists a “Large 3-inch Genuine TOTO Toilet Flapper” (part 2023) for tanks that need a brand-specific fit rather than a generic universal Korky Toilet Genius.

Mansfield is distinctive because some Mansfield toilets use a tower-style flush valve instead of a hinged flapper. Barrett 106, Brentwood 3147, Denali 3916, Maverick 102/112, Protector 1386, Summit ADA 386, and Waverty 3195 all sit on the 3-inch flapper table, while a Mansfield 210 or 211 tower needs a dedicated seal that replaces the original rigid flapper Korky 3-inch compatibility table, Korky flush-valve seal guide.

Glacier Bay and other private-label toilets show up on both the 2-inch and 3-inch tables, so the house-brand label alone tells you almost nothing. WCRS1 sits on the 2-inch table; N2428T, N2428RB, TQRS1NP4P1, 173-239, 331-725T, and 1002-109-308/N2442T sit on the 3-inch table Korky 2-inch table, Korky 3-inch table. Glacier Bay is a Home Depot house brand with its own N-prefix model numbering, and our Glacier Bay toilet parts guide covers the fill valve and flush-valve side of that toilet in more depth.

Brand / system	Best first identifier	Visual cue	Likely part
American Standard standard tanks	Tank number inside tank	Hinged flapper, 2-in. or 3-in. opening	2-in. flapper (Cadet, Evolution 2, Monarch, Mainstream) or 3-in. flapper (Cadet 3, Clean, Edgemere, Titan Elite)
American Standard Champion 3	Tank family + canister valve	Canister-style seal, no flapper	Korky 435 seal (replaces AS 738651-0070A)
American Standard Champion 4 / Eljer Titan 4	Champion 4/Pro, Eljer Titan 4 family	Large specialty seal	Korky 450 seal (replaces AS 7301111-0070A)
Kohler standard tanks	K-number inside tank	Hinged flapper	Korky 2017 (2-in. tanks) or Korky 3070 (3-in. tanks)
Kohler Class Five / Six	Class Five/Six canister	Canister/tower, circular seal	Korky 435 or Kohler GP1059291
TOTO	Tank number, often ST-prefixed	Standard or large hinged flapper	Korky 2017 (2-in. Carusoe) or Korky 3070/2023 (3-in. tanks)
Mansfield	Tank model or 210/211 valve	Tower valve or rigid flapper	Mansfield 210/211 seal, or Korky 3070 for listed 3-in. tanks
Glacier Bay / private-label	Tank number + flush-valve size	2-in., 3-in., or dual-flush	Size-match first, then dual-flush seal if not a hinged flapper
Unknown brand	Measure the opening	Orange/baseball = 2-in.; grapefruit/softball = 3-in.	Universal 2-in. or 3-in. flapper after ruling out a specialty seal

Manufacturer and Retailer Lookup Tools

Korky’s Toilet Genius is the strongest homeowner-facing identification tool in this space: it asks about the flushing system type, offers visual choices like “Flush Valve with Flapper” and “Tower Style,” and routes to a brand and part recommendation without requiring a serial number Korky Toilet Genius. That fits the real-world scenario where the tank stamp is worn or unreadable. Korky’s flapper-size guide is a simpler path when the brand itself is unknown, since it reduces the first decision to 2-inch versus 3-inch – though size alone can’t identify a specialty Kohler, Mansfield, or Champion seal Korky flapper size guide.

Retailer pages are a useful cross-check once you have a tank number or part number in hand. Home Depot’s listing for Korky’s 2017CM, for example, shows photos, a retailer model number, and its “universal standard 2-inch” claim with a 10-year warranty – helpful for verification, but weaker than a manufacturer table for confirming exact tank-number fit Home Depot Korky 2017CM. Once you’ve matched a brand and tank number from the table above, our free Repair Finder can help confirm the exact part before you make a trip to the store.

What to Do If You Still Can’t Identify the Brand

If every marking is gone, work through this fallback order: photograph the whole toilet, photograph the inside tank, photograph the flush valve from above, then measure the opening and compare it against visual part-finder images Korky Toilet Genius. If it’s a traditional hinged flapper, measure the opening and choose between the 2-inch and 3-inch path Korky flapper size guide. If it’s a tower or canister valve, compare the seal to the Kohler, American Standard Champion, and Mansfield examples above rather than buying a hinged flapper that won’t fit Korky flush-valve seal guide.

A universal flapper is a reasonable choice for a standard hinged flush valve. Korky’s 2-inch Ultra 2X is built to fit most 2-inch valves, including American Standard, Kohler, TOTO, and others, and the 3-inch Ultra 2X extends that list to American Standard, Aquasource, Crane, Eljer, Ferguson, Gerber, Glacier Bay, Jacuzzi, Kohler, Mansfield, Pegasus, and TOTO Korky 2-inch Ultra 2X, Korky 3-inch Ultra 2X. Korky also sells a Fit-All adjustable 2-inch/3-inch flapper for when you haven’t measured yet, though the company still recommends confirming the correct size once you can Korky flapper size guide.

Replace the whole flush valve – or the toilet – when the valve is damaged, the seat is pitted, the specialty valve is obsolete, or repeated seal swaps don’t stop the leak. That’s the escalation point once seal-matching genuinely fails, not the first move for an ordinary worn flapper Korky flush-valve seal guide.

When to Call a Plumber for ID

Some identification problems aren’t worth solving alone. Call a plumber when the toilet has a canister, pressure-assist, dual-flush, or specialty tower system and you can’t identify the seal without disassembly Korky flush-valve seal guide. Call a plumber when reaching the markings means disturbing the tank bolts, the flush-valve nut, or the tank-to-bowl gasket – that gasket is what seals the joint between tank and bowl, and it’s not a place to guess Korky toilet anatomy. And call a plumber if the toilet keeps running after you’ve installed a correctly sized flapper, since the real problem may be the flush-valve seat, the chain adjustment, the fill-valve water level, or the tank-to-bowl connection rather than the flapper itself Korky toilet anatomy.

For cost context, The Spruce reports an average plumber hourly rate of $105, ranging from $35 to $170 depending on area and experience, with common flat-rate leak repairs and unclogs starting around $150 to $190 The Spruce plumber cost guide. A short identification visit is often cheaper than two or three wrong parts orders on a proprietary valve, though the exact dispatch fee will vary by market The Spruce plumber cost guide.

What to Do Next

Once you know your toilet’s brand, tank number, and flush-valve style, our guide to replacing a toilet flapper walks through the swap step by step. If you’re still narrowing down 2-inch versus 3-inch, What Size Flapper Do I Need? goes deeper on measuring and chain adjustment. If your toilet turned out to be a canister or tower system rather than a hinged flapper, How to Identify Your Toilet Flush Valve covers that broader identification problem. For identifying the toilet itself – brand, model, and bowl/tank numbers beyond just the flapper – see How to Identify Your Toilet.

Glacier Bay owners can go straight to our Glacier Bay toilet parts guide. And if the toilet is still running after the new flapper goes in, Why Is My Toilet Running? 6 Common Causes rules out the fill valve and chain next. For the rest of the tank and bowl, the Toilet Repair Guide is the Pillar 2 hub and index for every article in this cluster.

Sources

• Korky: Toilet Genius Visual Parts Assistant
• Korky: Anatomy of a Toilet
• Korky: What Size Flapper Do I Need?
• Korky: What Flush Valve Seal Do I Need?
• Korky: 2-Inch Ultra 2X High-Performance Flapper Compatibility Table
• Korky: 3-Inch Ultra 2X Premium Universal Flapper Compatibility Table
• Home Depot: Korky Ultra 2X High Performance Flapper, Model 2017CM
• The Spruce: How Much Does a Plumber Cost?

Educational content only. Not a substitute for licensed professional advice. Local plumbing codes vary by jurisdiction. Use of any guidance from this guide is at your own risk.

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