Best Kohler‑Specific Toilet Flappers

TL;DR: The Kohler GP1078441 is a 3.25‑inch durable‑rubber flapper that fits Kohler Class Five two‑piece toilets, offers a 1.28 GPF seal, and earns a 4.5‑star rating from over 2,200 buyers.

This flapper’s standout spec is its 3.25‑inch diameter seal, paired with a compact 2.7‑inch height and a 7.5‑inch length that matches the original OEM design. At just 0.095 pounds, it’s lightweight enough for easy installation while still providing a solid rubber barrier that resists chemicals and corrosion.

Compared with the other four contenders, the GP1078441 sits in the middle of the weight range: it’s lighter than the GP1078440’s 0.11‑pound unit but heavier than the ultra‑light GP83064, which tips the scales at 0.01 pounds. Its 7.5‑inch length outstretches the GP89825’s shorter profile, and its 5.0‑inch width is broader than the GP83064’s 4.25‑inch width, giving it a more substantial seal area than the slimmer GP1078440.

Customers consistently award this flapper 4.5 stars out of 5, noting that it “fits perfectly” on models like Memoirs and Devonshire and restores the toilet’s original flush performance. Professional reviewers also highlight the precise 3.25‑inch seal as a key factor in preventing phantom flushes. The most common gripe is the chain length, which some users find either too short or too long and must adjust to avoid tangling.

Technically, the GP1078441 is engineered for Kohler’s Class Five flushing technology, delivering a 1.28 GPF water‑saving rate while maintaining the strong, chemical‑resistant rubber construction. It comes as a direct‑replacement, single‑count package with a chain included, and it’s backed by a 1‑year limited warranty.

Best for: Kohler two‑piece toilet owners with Class Five models who want a well‑reviewed, OEM‑grade replacement — the GP1078441 offers a 3.25‑inch diameter seal.

Avoid if: You have a one‑piece toilet, need a universal fit for other brands, or prefer a flapper without a chain that might need trimming.

TL;DR: The Kohler GP83064 is a 2‑inch, 7.5‑inch long, stainless‑steel‑chained flapper that fits select older Kohler one‑piece toilets, offering chemical resistance and a lightweight design for just $8.80.

This flapper’s standout spec is its 2‑inch diameter paired with a 7.5‑inch length, giving it a larger coverage area than many rivals. Weighing only 0.1 lb, it’s easy to handle during installation, and the TPR rubber construction resists chlorine and chloramine cleaners.

Compared with the other four contenders, the GP83064 is noticeably lighter than the GP1078440 (≈0.11 lb) and the GP1078441 (≈0.095 lb). Its 7.5‑inch length exceeds the 4‑inch length of the GP1078440 and matches the GP1078441, while its 4.25‑inch width sits between the narrower 3.25‑inch GP1078440 and the wider 5‑inch GP1078441. The GP89825 lists a shorter length and a heavier build, making the GP83064 a more compact, low‑profile option.

User feedback highlights a hassle‑free swap: reviewers repeatedly note that the exact OEM fit eliminates guesswork and restores proper flush performance in compatible models. Professional reviewers also point out the chemical‑resistant TPR material as a safeguard against harsh tank cleaners. The only recurring downside is the flapper’s limited compatibility—it’s a non‑universal, exact‑fit part for older Kohler one‑piece toilets, and the float is non‑adjustable, which may not suit every tank design.

Additional technical details reinforce its value: a stainless‑steel chain with hook provides durable linkage, the clip‑on installation type simplifies setup, and the product carries a one‑year limited warranty. Chlorine resistance further ensures longevity in homes that use standard tank cleaners.

Best for: Budget-conscious buyers seeking a reliable entry-level option — the Kohler GP83064 offers Flapper Diameter: 2 inches

Avoid if: You have newer Kohler models or a non‑Kohler toilet that requires a universal flapper

TL;DR: The Kohler GP1078440 is a 2‑inch shark‑fin rubber flapper for select Kohler one‑piece toilets, delivering corrosion resistance and an adjustable chain at a modest $10 price.

The standout dimension is its 2.1‑inch flapper center‑to‑center measurement, paired with a 2‑inch flapper diameter and a compact 4.0‑inch length. Its shark‑fin shape and corrosion‑resistant rubber material are engineered for a tight seal that helps conserve water.

At 0.11 pounds, this flapper is heavier than the ultra‑light GP83064 (0.01 lb) but only slightly heavier than the GP1078441 (0.095 lb) and the GP89825 (0.0875 lb). Its 4.0‑inch length is notably shorter than the 7.5‑inch lengths of both GP1078441 and GP83064, and its 3.25‑inch width is narrower than the 5.0‑inch width of GP1078441 and the 4.25‑inch width of GP83064, making it one of the more compact options in the lineup.

Reviewers consistently praise the corrosion‑resistant rubber construction, noting that it stays functional even in hard‑water environments. The shark‑fin seal is highlighted for preventing leaks, while the adjustable chain earns marks for easy installation. The primary criticism is its limited compatibility – it only fits select Kohler one‑piece models with bottom‑outlet flush valves, so it isn’t a universal replacement.

Technically, the GP1078440 is a direct‑replacement part designed for bottom‑outlet flush valves. The adjustable chain lets you fine‑tune the lift, and the rubber material is specifically formulated to resist chlorine, extending the part’s lifespan.

Best for: Budget-conscious buyers seeking a reliable entry-level option — the Kohler GP1078440 offers Flapper Center-to-Center Measurement: 2.1 inches

TL;DR: The Kohler GP89825 is a 2‑inch shark‑fin rubber flapper made for the Portrait K‑3357, offering durable, corrosion‑resistant sealing at $10.73 with an adjustable chain, though it fits only that model.

This flapper measures 50.8 mm in diameter, 63.5 mm tall, 101.6 mm long and 76.2 mm wide, and it weighs 0.0875 pounds (39.69 g). It’s built from premium‑quality rubber and features a shark‑fin seal that professionals cite for reliable leak prevention. The chain is adjustable, simplifying the fit for the Kohler Portrait K‑3357’s 2‑inch flush valve.

Compared with the other four contenders, the GP89825 shares the same 50.8 mm flapper size as the Kohler 1138648 and the GP1078440, but it is noticeably heavier than the 1138648’s 9.1 g and the GP83064’s 0.01 lb. Its height of 63.5 mm is a bit taller than the GP1078440’s 3‑inch profile, while the GP1078441 uses a larger 3.25‑inch diameter flapper, making the GP89825 a more compact choice for the specific Portrait model.

User feedback highlights a reliable fit for K‑3357 owners and praise for the rubber’s durability in hard‑water environments. However, several reviewers note confusion over compatibility, often trying to install it in other Kohler models such as the K‑3488. Expert reviewers also point out that the shark‑fin design and chlorine‑resistant rubber give this flapper a longer service life than standard vinyl options.

Additional technical details include standard chain material, 2‑inch flush‑valve compatibility, chlorine and hard‑water resistance, and a 1‑year limited warranty from Kohler. These specs reinforce its suitability for the Portrait line while underscoring its specialized nature.

Best for: Those prioritizing quality and willing to pay for premium performance — the Kohler GP89825 offers Flapper Diameter: 50.8 mm

Avoid if: You need a universal fit for other Kohler models or a larger 3¼‑inch flapper for high‑performance toilets.

TL;DR: The Kohler 1138648 OEM flapper fits 2‑inch, pre‑2004 two‑piece Kohler toilets, offers chemical‑resistant construction and a compact 50.8 mm size, but carries a higher price than many peers.

This flapper’s standout dimension is its 50.8 mm flapper size, matching the 2‑inch flush valve standard for older Kohler two‑piece models. At just 9.1 g, the unit is remarkably lightweight, and its 123.2 mm width provides a generous sealing surface.

Compared with the other four options, the 1138648 sits at the premium end of the price range. It is lighter than the GP89825’s 39.69 g and broader than that model’s 76.2 mm width, yet heavier than the ultra‑light GP83064 that weighs only 0.01 pounds. Its height of 58.4 mm is also taller than the GP83064’s 1.31 inches, giving it a sturdier profile.

Users appreciate that this is a genuine OEM part, noting that the chemical‑resistant material helps it endure harsh water conditions without degrading. Professional reviewers highlight the precise engineering that restores reliable tank‑to‑bowl flow. However, the limited compatibility—only Kohler two‑piece toilets made before 2004 and the San Raphael K‑3722—means it won’t fit newer or one‑piece models.

Best for: Those prioritizing quality and willing to pay for premium performance — the Kohler 1138648 offers Flapper Size: 50.8 mm

Avoid if: You have a modern Kohler toilet made after 2004 or a one‑piece model that requires a different flapper type