2 in vs 3 in Sizing, Which Flapper Fits Kohler, American Standard and TOTO, and the 10-Minute Dye Test
5 picks compared · prices, ratings and stock checked October 13, 2026
Our Top Pick
For a toilet with a 2 in flush valve, the Korky 100BP Standard 2-Inch Ultra High Performance Universal Toilet Flapper. For a 3 in flush valve, the Fluidmaster 5403 Universal 3-Inch Toilet Flapper. If you cannot open the tank to measure before ordering, the Fluidmaster 523A-009-T4 Super Flapper fits either size.
4.5 on Amazon · 16,906 ratings
Quick answer
The best toilet flapper for the 2 in flush valve in most toilets is the Korky 100BP Standard 2-Inch Ultra High Performance Universal Toilet Flapper, rated 4.5 stars across 16,906 Amazon ratings; if the opening at the bottom of your tank is closer to 3 in across, buy the Fluidmaster 5403 Universal 3-Inch Toilet Flapper instead. Size is set by that opening, not the toilet brand: about the size of a baseball means 2 in, closer to a softball means 3 in. Confirm the leak first with EPA's dye test: a few drops of food coloring in the tank, wait 10 minutes, and color in the bowl means the flapper is not sealing.
Every pick below is currently stocked — ratings and stock read from Amazon on 13 October 2026.
Best for: Replacing a worn flapper on a 2 in flush valve when you want one part that fits most brands
Listing verified 13 Oct 2026
Best for: A 3 in flush valve in a 1.28 or 1.6 gpf toilet, especially where in-tank chlorine tablets are used
Listing verified 13 Oct 2026
Best for: Matching a 3 in flapper to a less common brand such as Gerber, Glacier Bay, Eljer or Mansfield
Listing verified 13 Oct 2026
Best for: Landlords and multi-bathroom homes replacing 2 in flappers on a schedule
Listing verified 13 Oct 2026
Best for: A toilet whose flush valve size you cannot measure, such as a rental you are repairing in one visit
Listing verified 13 Oct 2026
How this page was made: we compare the current Amazon listings, the makers' published specs and what verified buyers report, then rank by fit for the job. Ratings, review counts and stock are read from Amazon and dated. We earn a commission on purchases through our links; it does not change the order. Reviewed by Marcus Reed, IICRC-certified Water Restoration Technician.
Full Reviews
Each pick in detail: what the listing states, what buyers report, and where it falls short.
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Listing verified 13 Oct 2026
See it on Amazon ↗Best Overall (2 in)
Quick Verdict
Korky 100BP Standard 2-Inch Ultra High Performance Universal Toilet Flapper: the widest stated fit of any 2 in flapper on this page.
Key Specs
Flush valve size
2 in
Fits (stated)
Most 2 in toilets, including American Standard, Kohler, Mansfield and TOTO
Tank sizes (stated)
Adjusts to fit 1.28, 1.6, 3.5 and 5 gallon per flush toilets
Replaces (stated)
Rubber, float-style and rigid-frame flappers
Material
Rubber; the compound is not named on this listing
Made in
USA (Wisconsin), per the listing
Pros
Cons
Suited to
Replacing a worn flapper on a 2 in flush valve when you want one part that fits most brands
Our take
The reason this flapper sits at rank 1 is the adjustment range. Korky states it fits 1.28, 1.6, 3.5 and 5 gallon per flush tanks, which spans a 1980s toilet and a current high-efficiency one, so you are unlikely to buy the wrong 2 in flapper. The brand list on the listing, American Standard, Kohler, Mansfield and TOTO, covers most of what is installed in US homes. What the listing leaves out matters too: it does not describe the adjustment mechanism or name the rubber, so if your tank holds a chlorine tablet you cannot tell from this page how the material will cope. Measure the flush valve opening before you order. If it is closer to 3 in across, this flapper will not seal, and no adjustment will fix that.
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These open a search for this model. We quote prices only where we can verify them — Amazon, Sylvane and eBay.
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Listing verified 13 Oct 2026
See it on Amazon ↗Best 3 in Flapper
Quick Verdict
Fluidmaster 5403 Universal 3-Inch Toilet Flapper: a silicone seal and a volume dial for 3 in high-efficiency toilets.
Key Specs
Flush valve size
3 in only; the listing says it is not designed for 2 in flush valves
Best for (stated)
High-efficiency 1.28 to 1.6 gallon per flush toilets
Seal material (stated)
Silicone, described as chlorine and hard-water resistant
Adjustment (stated)
Dial sets flush volume
Frame (stated)
Solid frame, said to resist twisting
Chain (stated)
Adjustable-length kink-free chain
Pros
Cons
Suited to
A 3 in flush valve in a 1.28 or 1.6 gpf toilet, especially where in-tank chlorine tablets are used
Our take
A 3 in flush valve dumps water faster than a 2 in one, which is how newer high-efficiency toilets clear the bowl with 1.28 gallons. The flapper covering that opening has to seal a larger area, and a hard, warped rubber disc is the usual failure. Fluidmaster uses a silicone seal here, and silicone generally keeps its flexibility in chlorinated water better than plain rubber, which matches the chlorine and hard-water claim on the listing. The dial matters for a different reason: an adjustable flapper lets you shorten the flush on a tank that was over-flushing, which saves water, but set too low it can leave waste in the bowl. Begin at the middle setting and move one step at a time. Note the listing's own warning: this flapper will not fit a 2 in valve.
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Listing verified 13 Oct 2026
See it on Amazon ↗Best Brand Fit List (3 in)
Quick Verdict
Korky 3062 Large 3-Inch Premium Toilet Flapper: a twelve-brand fit list in a two-pack.
Key Specs
Flush valve size (stated)
3 in; adjusts to fit all 3 in flush valves found in newer HET toilets
Fits (stated)
American Standard, Aquasource, Crane, Eljer, Ferguson, Gerber, Glacier Bay, Jacuzzi, Kohler, Mansfield, Pegasus and TOTO
Material (stated)
Korky's red rubber, described as its longest-lasting compound
Quantity
2 flappers
Made in
USA, per the listing
Chain
Stainless steel attachment, per Korky's single-pack listing for the same flapper
Pros
Cons
Suited to
Matching a 3 in flapper to a less common brand such as Gerber, Glacier Bay, Eljer or Mansfield
Our take
Most flapper listings name three or four brands. This one lists twelve, and the additions are the ones that trip people up: Gerber, Glacier Bay, Eljer, Crane, Mansfield and Jacuzzi toilets turn up in a lot of US homes and are often missing from universal claims. The listing says the flapper adjusts to fit every 3 in flush valve found in newer high-efficiency toilets, and Korky's single-pack page for the same flapper adds that the rubber is chlorine resistant with a stainless steel chain attachment. Red rubber is Korky's standard material rather than silicone, so if your tank holds a chlorine tablet, lift the lid once a year and press the flapper edge; a hard or cracked edge is the sign to swap it. Buy the pair if you have two 3 in toilets or want one on the shelf.
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Listing verified 13 Oct 2026
See it on Amazon ↗Best Multi-Pack (2 in)
Quick Verdict
Fluidmaster 502 Universal 2-Inch Toilet Flapper 3-Pack: adjustable 2 in flappers for homes that replace them on a schedule.
Key Specs
Flush valve size
2 in
Tank sizes (stated)
1.28 to 3.5 gallons per flush
Adjustment (stated)
Dial sets flush volume
Material (stated)
Solid frame with Microban material, described as chlorine and hard-water resistant
Quantity
3 flappers
Install time (stated)
10 minutes or less
Pros
Cons
Suited to
Landlords and multi-bathroom homes replacing 2 in flappers on a schedule
Our take
Flappers are a wear part, and if you own a rental or a home with three or four toilets, the sensible move is to replace them on a schedule rather than waiting for the dye test to fail. Fluidmaster's 502 in a three-pack suits that. Each flapper has the same solid frame and volume dial as the single 502, which lets you set each toilet's flush separately, useful when one bowl needs a fuller flush than another. The Microban mention on the listing describes an additive in the material, and the chlorine and hard-water resistance claim is Fluidmaster's own. One limit: the stated range is 1.28 to 3.5 gpf, so a very old 5 gallon tank is outside it. Store the spares flat and out of sunlight so the material does not set.
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Listing verified 13 Oct 2026
See it on Amazon ↗Best If You Cannot Measure First
Quick Verdict
Fluidmaster 523A-009-T4 Super Flapper: the one to buy when you cannot measure the flush valve first.
Key Specs
Flush valve size (stated)
2 in or 3 in
Adjustment (stated)
Adjustable to set water use per flush
Fit (stated)
Universal for most toilets
Material
Not stated on this listing
Chain
Not described on this listing
Warranty (stated)
10 years
Pros
Cons
Suited to
A toilet whose flush valve size you cannot measure, such as a rental you are repairing in one visit
Our take
Guessing the valve size wrong is the most common way a flapper purchase fails, and this is Fluidmaster's answer to it: one flapper the listing says fits both 2 in and 3 in flush valves. That makes it the pick for a toilet you cannot inspect before buying, or for a landlord carrying one part for mixed toilets. The listing is thin otherwise. It does not name the material, describe the chain, or explain how one flapper seals two openings, so you are trusting the 10-year warranty and the Amazon's Choice flag more than a spec sheet. For a toilet you can open and measure, the single-size flappers above have far longer buyer records. After fitting this one, run the dye test a week later to confirm the seal has settled.
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What to know before you buy.
A flapper leak makes no puddle. Water slips from the tank into the bowl around the seal, the fill valve tops the tank up, and the only clue is a toilet that refills by itself now and then or a water bill that has crept up. EPA WaterSense says an old or worn flapper can cause your toilet to flush on its own or silently leak thousands of gallons a year, and that the average household's leaks waste more than 9,300 gallons a year. The test takes 10 minutes. Put a few drops of food coloring in the tank, do not flush, and look in the bowl after 10 minutes. Color in the bowl means water is getting past the flapper. Clear water means the flapper is fine, and a running toilet has another cause, usually the fill valve or a water level set above the overflow tube.
Flappers come in two sizes, and the size is set by the opening at the bottom of the tank, not by the brand. Turn off the supply, flush to empty the tank, and look at the hole the flapper covers. Korky's own sizing guide puts it plainly: an opening about the size of a baseball or an orange takes a 2 in flapper; one closer to a softball or a grapefruit takes a 3 in. A tape measure across the opening settles it. Older toilets mostly use 2 in valves, and many high-efficiency toilets sold since the mid-2000s use 3 in, but there are exceptions both ways, so measure. The flapper itself is wider than the valve it fits, which is why measuring the old flapper misleads people. If you cannot open the tank before ordering, the Fluidmaster 523A-009-T4 fits either size.
Most Kohler, American Standard and TOTO toilets take a universal flapper of the right size, and Korky and Fluidmaster both name those brands on their listings. The exceptions are what catch people. Many Kohler toilets with a canister flush valve have no flapper at all; the seal is a flat ring under a canister that lifts straight up. Some Kohler toilets with a Class Five flush use a 3 in flapper with a float on the chain. Mansfield's flush tower uses a seal ring instead of a hinged flapper. Lift the lid and look before you order: a flat disc hinged on two pegs beside the overflow tube is a standard flapper, and anything that lifts straight up or has a cup underneath is a different part that takes the maker's own number. Korky's 3062 listing names twelve brands, which helps with Gerber, Glacier Bay, Crane and Jacuzzi.
An adjustable flapper has a dial or a float that changes how long it stays open, which sets the flush volume. Fluidmaster's 5403, 502 and 523A all use a dial; Korky's 100BP adjusts to tank size. Fixed flappers are simpler and fine when the old flush was right. Whatever you buy, set the chain with about 1/2 in of slack when the flapper is closed: too tight and the flapper cannot seal, which is itself a leak; too loose and the chain catches under the flapper or the handle has to travel too far. In-tank chlorine tablets are the other thing to know. The flapper soaks in that water, and plain rubber hardens and cracks sooner in chlorinated water, which is why Korky calls its rubber chlorine resistant and Fluidmaster fits a silicone seal to the 5403. If you use tablets, buy one of those and check the flapper edge yearly.
A new flapper fixes one thing: water passing the seal at the bottom of the tank. It does nothing for water on the floor. A toilet that leaks at the base on every flush has a failed wax seal, not a flapper problem. A tank that keeps running with a new flapper in it has a fill valve that will not shut off or a water level set above the overflow tube. A flush that is weak with the new flapper usually means a chain or dial set wrong, or a flush valve seat that is pitted or cracked, which no flapper can seal and which means replacing the whole flush valve. That last job means lifting the tank off the bowl, and if the tank bolts are rusted solid or the toilet is a one-piece, a licensed plumber is the right call. HearthDry's phone line reaches water damage restoration companies, not plumbers.
Once the new flapper is in, flush twice and watch the tank refill. The water should stop about 1 in below the top of the overflow tube; if it climbs higher, turn the fill valve's adjustment down, because water over the tube runs to the bowl and looks exactly like a flapper leak. Then repeat the dye test a day later. If color still reaches the bowl, the flush valve seat under the flapper is probably rough or scaled: with the tank empty, run a finger around the rim and clean it with a scouring pad, since a thin ridge of lime is enough to hold the flapper open. Write the date on the inside of the tank lid. Flappers wear faster in hard water and with tablets, and a yearly dye test catches the next failure before the water bill does.
Run EPA's dye test: a few drops of food coloring in the tank, no flushing, and a look in the bowl after 10 minutes. Color in the bowl means water is passing the flapper and it needs replacing.
Other signs are a toilet that refills by itself every so often, a flapper edge that feels hard or has a groove worn into it, and a rising water bill with no other explanation.
Look at the flush valve opening at the bottom of the tank with the water off and the tank empty. Korky's sizing guide says an opening about the size of a baseball or an orange takes a 2 in flapper, and one closer to a softball or a grapefruit takes a 3 in.
A tape measure across the opening settles it. Do not measure the old flapper, which is wider than the valve it fits.
Within a size, mostly. A universal 2 in or 3 in flapper from Korky or Fluidmaster fits most American Standard, TOTO, Gerber, Mansfield and many Kohler toilets, and both brands list the names on their pages.
The exceptions are toilets without a hinged flapper: Kohler canister flush valves use a flat seal under a canister, Mansfield flush towers use a seal ring, and some Kohler Class Five toilets use a 3 in flapper with a float. Those take the maker's own part.
Age and water chemistry. Rubber hardens, warps and cracks over years of sitting in water, and in-tank chlorine tablets speed that up, which is why chlorine-resistant rubber and silicone seals exist.
Hard water leaves scale on the flush valve seat so the flapper no longer sits flat. A chain set too short holds the flapper slightly open, and a chain too long can catch under it. Any of these lets water past the seal.
Because the flapper was not the only problem, or the new one is not seated. Check the chain has about 1/2 in of slack and is not caught under the flapper.
Check the water line sits about 1 in below the top of the overflow tube; if it is higher, water pours down the tube and the fill valve never stops. Then run the dye test again. Color in the bowl with a new flapper usually means a scaled or cracked flush valve seat.
There is no fixed number. None of the listings on this page states a service life, and the two Fluidmaster flappers with a 10-year warranty are covering defects, not predicting wear.
Hard water, in-tank tablets and a chain kept tight all shorten it. The practical answer is a dye test once a year and a replacement when color shows in the bowl or the flapper edge has gone hard.
Call (888) 840-6512. The line is answered 24 hours a day, seven days a week, and connects you with an IICRC-certified water damage restoration company that serves your area. A recorded menu picks up first: choose water damage or mold, key in your 5-digit ZIP code, and hold through the short silence while the call is passed to the company.
Describe what you can see — where the water is coming from, how long it has been there, and whether it smells — the more specific you are, the faster the right company is on the line. If the source is a pipe or an appliance, shut the main water valve first. Have four things ready and the call goes quickly: the address, when the water started, what is wet now, and whether you have filed an insurance claim.
Still not sure which of these is your situation? (888) 840-6512 · toll-free · answered 24/7
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