Kohler Toilet Flapper: 2-Inch vs 3¼-Inch (Class Five)

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Quick answer from a licensed plumber: First check that it is a flapper toilet at all: many Kohlers use a canister with a seal instead. If it has a flapper, measure it. A 3¼-inch flapper means a Class Five toilet; Kohler lists the GP1078441 for two-piece Class Five models. A 2-inch flapper on a two-piece toilet takes the GP85160 (with float) or GP87449 (without float); on a one-piece, Kohler lists the GP84995 or GP1078440 for various models, so check the lid label. The part number is often printed under the tank lid.

Two-piece Kohler with a 2-inch flapper and a float? Kohler’s part is the GP85160. See the Kohler GP85160 on Amazon

Kohler Flappers at a Glance

Kohler’s toilet service parts catalog sorts its gravity toilets by flushing technology. Only some of them use a flapper at all:

Two rules from that catalog do most of the work: a 3¼-inch flapper means a Class Five toilet, and all Class Five toilets use the GP1083167 fill valve. Kohler says toilets made before 2004 most commonly have a 2-inch flapper.

Step 1: Canister or Flapper?

Lift the lid. Kohler says that if you have a canister toilet “you will not see a flapper in the tank but a cylinder-shaped flush valve. These toilets do not use a flapper, but a seal.” Dual flush Kohlers, with two buttons on top instead of a lever, are canister toilets too. If that is what you see, a flapper will not fit; go to our Kohler canister flush valve seal guide.

Step 2: Read the Label Under the Lid

Kohler says that on toilets made after 1990, “various service part numbers are listed on the underside of the lid,” and the toilet’s own number is “imprinted on the inside back of the tank.” If the lid label lists a flapper number, buy that part. Toilets made before 1990 have no lid label, so look up the tank number in Kohler’s service parts catalog (linked below), which lists the flapper for each toilet, or use the table above.

Step 3: Measure the Flapper

A Kohler flapper is either about 2 inches across or 3¼ inches across. Neither is the common 3-inch size. Some universal 3-inch flappers do claim a Kohler fit (Fluidmaster lists its 5403 for the Kohler Cimarron), but the part Kohler lists is the one made for your toilet. If yours is 3¼ inches, it is a Class Five toilet: Kohler lists the GP1078441 for two-piece Class Five toilets and a model-specific flapper for one-piece models.

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2-Inch Two-Piece: GP85160 or GP87449?

Kohler’s catalog says to match the flapper that resembles your old one. The Amazon listings for the genuine parts describe the difference:

• GP85160 is a 2-inch flapper with a float, used in various 1.6 gpf two-piece toilets per its listing, which names Wellworth, Portrait and Memoirs models among others. Kohler’s current page says it fits “Portrait, Wellworth, Highline, Memoirs, and more.”
• GP87449 is a 2-inch flapper without a float, used in various two-piece toilets with 3.5+ gpf per its listing, which names some Wellworth and Highline models among others.
• GP49114: Kohler says older toilets “may have a black flapper; replace with GP49114.”

Which Fill Valve Goes With It

If a new flapper does not stop the running, the fill valve is next. Kohler’s catalog pairs them like this: all 2-inch two-piece toilets use GP1138930, and all Class Five toilets use GP1083167, the red-cap valve. The Amazon listings for the genuine Kohler parts add a quick check: look at the shank color of the old valve. Black means GP1083167; gray means GP1138930.

What to Buy

Genuine Kohler parts, matched to the table above. Check your tank or lid number against the model list on each listing:

• 2-inch two-piece, flapper with float: Kohler GP85160 flapper with float, sold by Amazon.
• 2-inch two-piece, flapper without float (3.5+ gpf toilets): Kohler GP87449 flapper, 2-pack, sold by Amazon.
• 2-inch one-piece: Kohler GP84995 hinge flapper, sold by Amazon. Its listing names Rosario 3434, Rialto 3386, San Raphael and Revival 3360 models.
• 3¼-inch Class Five two-piece: Kohler GP1078441 Class Five flapper, sold by Amazon. Its listing names Memoirs, Bancroft, Devonshire and Cimarron two-piece models.

Parts You’ll Also Need

Only if the fill valve is also leaking or noisy:

• Class Five (black shank, red cap): Kohler GP1083167 fill valve kit, sold by Amazon.
• 2-inch flapper toilets (gray shank): Kohler GP1138930 fill valve kit, sold by Amazon.

When to Call a Licensed Plumber

• You have a Power Lite toilet (a cord runs to an outlet) or a Pressure Lite toilet (a pressure vessel inside the tank). Kohler says both use model-specific parts.
• Water drops below the flapper to the base of the flush valve, which means the flush valve or its gasket, and the tank has to come off.
• The shutoff valve will not close.

FAQ

What size flapper does a Kohler toilet use?

Either 2 inches or 3¼ inches, per Kohler’s service parts catalog. Toilets with a 3¼-inch flapper are Class Five toilets; 2-inch flappers are most common on toilets made before 2004. Canister toilets use a seal, not a flapper.

What flapper fits a Kohler Class Five toilet?

Kohler lists the GP1078441 for two-piece Class Five toilets, replacing parts 1016546 and 1042313. One-piece Class Five models use model-specific flappers, such as GP1039444 for Cimarron and Memoirs one-piece toilets.

What is the difference between Kohler GP85160 and GP87449?

Both are 2-inch flappers for two-piece toilets. Per their listings, the GP85160 has a float and is used in 1.6 gpf toilets, and the GP87449 has no float and is used in 3.5+ gpf toilets. Kohler says to match the one that resembles your old flapper.

Where is the part number on a Kohler toilet?

On toilets made after 1990, Kohler prints service part numbers on the underside of the tank lid, and the toilet number is imprinted on the inside back of the tank. Older toilets have no lid label.

Which Kohler fill valve do I need, GP1083167 or GP1138930?

Kohler’s catalog lists GP1083167 (red cap) for all Class Five toilets and GP1138930 for 2-inch-flapper two-piece toilets. The Amazon listings for the genuine parts add a check: a black shank means GP1083167 and a gray shank means GP1138930.

Why Trust Plumbing Picks

Plumbing Picks is written by a licensed Georgia journeyman plumber. Every part number, size and fit on this page comes from the manufacturer pages and documents listed below, which we opened and read; product details come from those makers and from the Amazon listings, not from hands-on testing. Each linked product was shipped or sold by Amazon, new and in stock, when we checked on September 24, 2026. Nobody pays to be included here. Where a link goes to Amazon we may earn a commission at no extra cost to you. More on who writes this and how we pick.

Sources

• Kohler: Toilets Service Parts catalog (May 2011)
• Kohler: Toilet Flapper with Float, K-GP85160
• Kohler: Silent Fill Toilet Valve Kit, K-GP1138930
• Kohler: Silent Fill Valve Kit for Kohler Class 5 Toilets, K-GP1083167
• Fluidmaster: 5403 Universal Adjustable 3″ Flapper

Bottom Line

Canister or flapper first; then the lid label; then the size. 3¼ inches means Class Five and the GP1078441 on a two-piece. 2 inches means GP85160 or GP87449 on a two-piece and GP84995 or GP1078440 on many one-pieces. Match the fill valve by shank color if you replace it too.