The 5 best toilet flappers for US homeowners in 2026 — Korky 100BP, Korky 3060BP, Korky 2017BP 2X Ultra, Fluidmaster 502P21 and TOTO THU500S reviewed and compared.
A running toilet is one of the most common and most fixable household plumbing problems — and in the vast majority of cases, a single worn-out rubber part is to blame. The toilet flapper is the rubber seal at the bottom of your tank that opens when you flush and closes to hold water for the next flush. When it degrades, water silently leaks from the tank into the bowl, your fill valve runs constantly to compensate, and your water bill quietly climbs. A replacement flapper costs just a few dollars and takes under ten minutes to fit — no plumber required.
We’ve identified the five best toilet flappers for US homeowners in 2026, covering universal 2-inch and 3-inch options, premium long-life formulations, and the OEM replacement that solves compatibility problems on TOTO toilets. Whether you’re fixing a running toilet for the first time or stocking a spare for your next repair, our guide to how to fix a running toilet covers the full diagnostic process. If you need to replace the fill valve at the same time, see our best toilet fill valves guide — and for a complete tank rebuild in one kit, our best toilet repair kits guide covers all-in-one solutions.
In This Guide
| Product | Rating | Best For | Price |
|---|---|---|---|
| Korky 100BP Ultra Standard 2″ Universal Flapper BEST OVERALL | ★★★★★ | Standard 2″ flush valves (most toilets) | $ |
| Korky 3060BP Universal 3″ Large Flapper | ★★★★★ | Large 3″ flush valves | $ |
| Korky 2017BP 2X Ultra High Performance 2″ | ★★★★★ | Long-term 2″ durability | $ |
| Fluidmaster 502P21 PerforMAX Universal 2″ | ★★★★★ | Adjustable fit + water saving | $ |
| TOTO THU500S Replacement Flapper 3″ | ★★★★★ | TOTO toilet owners | $ |
🏆 Best Overall Most Popular
The Korky 100BP is the most widely used replacement toilet flapper in the US — and its reputation is built on decades of real-world performance in American homes. Korky has been manufacturing rubber plumbing parts in the US since 1952, and the 100BP’s 2-inch universal fit works with virtually every standard residential toilet right out of the package, with no modifications or adjustments required. The Korky rubber compound outlasts the thin imported alternatives found in budget packs, which is exactly why it’s the part most plumbers and confident DIYers reach for first when a toilet starts running.
Installation is straightforward enough for a complete beginner: unhook the chain from the handle arm, unclip the two ear tabs from the overflow tube, fit the new flapper, reattach the chain with the correct amount of slack, and test. No tools needed. If you’re fixing a running toilet for the first time, see our complete guide to how to fix a running toilet for the full step-by-step walkthrough.
⭐ Our Top Pick Bestselling
The Korky 3060BP is the correct answer for anyone with a 3-inch flush valve — found in many newer water-saving and high-efficiency toilets. A standard 2-inch flapper will not seal a 3-inch valve seat no matter how carefully it’s installed, so if your current flapper is visibly larger than a typical 2-inch part, this is what you need. The same Made in USA Korky rubber quality that makes the 100BP the go-to standard flapper applies here, scaled to the larger flush valve geometry found in modern high-efficiency toilet designs.
Compatibility covers the most common 3-inch flush valve configurations found in US residential toilets, including American Standard and Kohler models with large flush openings. A bestselling choice with strong, consistent sales that reflect genuine homeowner satisfaction. If you’re unsure whether you have a 2-inch or 3-inch flush valve, see the measuring guide in our buying guide section below before ordering.
🎯 Staff Pick Made in USA
The Korky 2017BP 2X Ultra is the premium tier of the Korky flapper range — the same 2-inch universal fit as the 100BP, manufactured from a denser rubber compound engineered for twice the lifespan. If you’ve been replacing your toilet flapper every one to three years and want to break that cycle, this is the product to reach for. The 2X lifespan advantage is especially meaningful in homes with chloramine-treated municipal water — used by many US water systems as a chlorine alternative — which degrades standard rubber compounds significantly faster than traditional chlorine treatment.
For homeowners tired of the same repair on the same toilet, the small premium over the standard 100BP is minimal against the potential to double your time between replacements. The installation process is identical to the 100BP — same two-ear clip design, same chain attachment, same 2-inch universal compatibility. A sensible upgrade wherever long-term reliability matters more than the lowest possible sticker price.
💰 Best Value Well Reviewed
Fluidmaster is the brand name most professional plumbers associate with toilet fill valves and flappers, and the 502P21 PerforMAX is their standout replacement flapper. The key differentiator is the adjustable solid frame: where standard flappers rely on two fixed ear tabs that clip onto the overflow tube, the PerforMAX’s frame self-adjusts to accommodate a wider range of valve seat geometries — making it the more versatile pick when you’re not fully certain of your toilet’s exact valve configuration. It’s particularly useful in older homes where the toilet may predate today’s fully standardized valve seat dimensions.
The water-saving design is a meaningful added benefit. The 502P21’s controlled-close mechanism regulates how long the flapper stays open per flush, which can reduce per-flush water consumption compared to a standard rubber flapper with no flow restriction. One of the most well-reviewed flappers in the US market with an enormous track record across both professional and DIY installs. If you need the broadest possible compatibility and prefer Fluidmaster’s mechanical design approach over Korky’s rubber-compound approach, this is the pick.
👷 Pro Choice OEM Quality
For owners of TOTO toilets — one of the most popular premium toilet brands in the US — the THU500S is the genuine OEM replacement flapper for TOTO’s 3-inch flush valve tanks. TOTO uses proprietary flush valve geometry in many of their toilet models, and universal flappers frequently fail to seat correctly on TOTO valve seats even when installed exactly according to instructions. The THU500S eliminates that compatibility problem entirely: it is the exact flapper TOTO engineered for their own valve seat geometry, and it fits the first time.
If you have a TOTO toilet that continues running after a universal flapper replacement, the OEM part is almost certainly the answer. The additional cost over a universal alternative is small compared to the ongoing water waste and frustration of a flapper that won’t seal on a high-end toilet. A consistently popular choice with solid month-to-month sales driven by TOTO owners who have already tried the universal route and need the right part.
The most common sign is a running toilet — a persistent hissing or trickling sound from the tank that continues between flushes. This means water is leaking from the tank into the bowl faster than it should, and the fill valve runs constantly to keep up. The definitive at-home check: add a few drops of food coloring to the toilet tank and wait 15 minutes without flushing. If color appears in the bowl, your flapper is leaking and needs replacement.
Other signs include phantom flushes (the toilet randomly starts refilling on its own without being flushed), a toilet that takes an unusually long time to refill after flushing, or an unexplained spike in your water bill. A running toilet can waste over 200 gallons of water per day, making this one of the most cost-effective plumbing repairs you can make. For a complete diagnosis covering all possible causes, see our full guide on how to fix a running toilet.
Flush valve openings come in two standard sizes, and choosing the wrong one means the flapper will never seal properly. A 2-inch opening is found in the majority of older and mid-range US residential toilets — the vast majority of toilets manufactured before 2005, and many built since. A 3-inch opening is common in newer high-efficiency and water-saving toilet models, where the larger opening allows a faster, more powerful flush with less water.
The quickest way to tell: remove the tank lid and place your hand flat over the flush valve opening at the bottom of the tank. If your palm covers it comfortably, it’s a 2-inch valve. If the opening is noticeably larger than your palm — roughly the size of a large orange — it’s a 3-inch valve. You can also check the toilet’s brand and model number (usually stamped inside the back wall of the tank), look up the manufacturer’s specifications online, or take the old flapper with you to the hardware store for a direct side-by-side comparison.
Universal flappers from Korky and Fluidmaster are designed to fit the standard two-ear overflow tube configuration found in the vast majority of US residential toilets. For most homeowners, a universal flapper is the right choice — it’s available everywhere, straightforward to install, and will solve the running toilet problem without requiring any brand or model research.
Brand-specific flappers become necessary for premium toilet brands with proprietary flush valve designs — most notably TOTO, and some American Standard ClassicClean and Mansfield models. If a universal flapper is correctly installed and the toilet continues to run, the valve seat geometry almost certainly requires the manufacturer’s own replacement part. For full tank rebuilds covering the flush valve and fill valve together, our guide to the best toilet repair kits covers complete all-in-one solutions.
Both are excellent and both are trusted by professional plumbers across the US. The meaningful difference is in design philosophy rather than overall quality. Korky’s advantage is in rubber compound quality — their Made in USA formulations are known for long service life and consistent seals, and the 2017BP 2X Ultra takes that further with a chloramine-resistant compound built for twice the standard lifespan. Fluidmaster’s advantage is in mechanical versatility — the PerforMAX’s adjustable solid frame provides a more adaptable fit across different valve seat geometries and adds a water-saving close mechanism that straight rubber flappers don’t have.
For a straightforward 2-inch replacement on a standard toilet, the Korky 100BP or 2017BP are hard to beat on pure simplicity and durability. When valve geometry isn’t certain or when water conservation is a priority, the Fluidmaster 502P21’s adjustable design gives you more flexibility. Either brand will fix a running toilet.
A standard rubber toilet flapper typically lasts 4–5 years under normal use. In homes with chloramine-treated municipal water — used as a disinfectant alternative to chlorine in many US city water systems — standard rubber can degrade in as little as 2–3 years. If you’re replacing your flapper every year or two, switching to the Korky 2017BP 2X Ultra’s chloramine-resistant compound is worth the small additional cost. Hard water also accelerates flapper wear by building up mineral deposits on the rubber that gradually prevent a clean seal.
Most plumbers recommend inspecting the flapper every 3–5 years as part of routine toilet maintenance. A quick test: press down gently on the flapper while the tank is filling. If the running sound stops when you apply pressure, the flapper’s seal is weakening and replacement is overdue. If you’re also noticing fill valve issues at the same time — slow refill, inconsistent water level — check our guide to the best toilet fill valves for the most reliable replacement options.
Sometimes a job is too big for DIY. If you need a licensed plumber in your area, search PlumberArchive.com — the US plumber directory with 12,151+ verified plumbers across all 50 states.
Find a trusted plumber near you →
Looking for our top recommended tools in one place? Browse our curated Amazon Storefront →
Get weekly plumbing tips, honest tool reviews and DIY guides delivered to your Facebook feed.
Most US toilets take a 2-inch flapper — this is the standard for the majority of residential toilets manufactured before 2005 and many built since. To verify, remove the tank lid and place your hand flat over the flush valve opening at the bottom of the tank. If your palm covers it comfortably, it’s a 2-inch valve. If it’s noticeably larger — roughly the size of an orange — you have a 3-inch valve, common in newer high-efficiency models. You can also check the brand and model number stamped inside the back wall of your tank and look up the manufacturer’s recommended flapper size, or take the old flapper to the hardware store and match it directly.
Three common causes cover the majority of cases. First, chain length: too short and the chain holds the flapper slightly open causing a constant slow leak; too long and excess chain falls under the flapper and breaks the seal. Aim for about half an inch of slack when the handle is at rest. Second, wrong size: a 2-inch flapper on a 3-inch valve will never seal no matter how carefully it’s fitted — check your valve size as described above. Third, damaged valve seat: if the circular ridge the flapper presses against is corroded or pitted, no flapper will hold a perfect seal. Run your fingertip around the valve seat — if you feel roughness or scoring, the flush valve itself needs replacing, at which point a complete toilet repair kit is the most cost-effective solution. For the full diagnostic walkthrough, see our guide on how to fix a running toilet.
Most plumbers recommend proactive inspection every 3–5 years, even if the toilet appears to be working normally. In practice, homeowners typically wait until a running sound appears. If your home has chloramine-treated municipal water or hard water, check more frequently — every 2 years is a reasonable habit. The practical test: press gently on the flapper while the tank is filling. If the fill valve goes quiet when you apply pressure, the flapper seal is weakening and replacement is worth doing now rather than waiting for the toilet to start running. At a few dollars and ten minutes per replacement, proactive swaps are far cheaper than the water waste a failing flapper causes every day.
Universal flappers work correctly on the vast majority of US residential toilets that use the standard two-ear overflow tube design — which covers most toilets from the major brands including American Standard, Kohler, and Mansfield standard models. The exceptions are premium brand toilets with proprietary valve geometries, most notably TOTO, where the seal surface geometry is different from the universal standard. If you install a universal flapper correctly and the toilet continues to run, your toilet almost certainly needs the manufacturer’s own replacement part. Check your toilet’s model number and the manufacturer’s parts list before purchasing a second universal flapper.
For most US homeowners, the Korky 100BP is the toilet flapper to buy — the most widely used 2-inch replacement in the country, made in the USA, and compatible with virtually every standard flush valve. It fixes a running toilet in under ten minutes for well under the cost of any service call.
If you’re also dealing with fill valve issues — slow refill, inconsistent water level, or a fill valve that won’t shut off — see our guide to the best toilet fill valves for the most reliable replacements. For a full tank rebuild covering the flapper, fill valve, and flush valve in one kit, our best toilet repair kits guide covers complete all-in-one solutions. And for the full step-by-step process from diagnosis to fix, our guide on how to fix a running toilet walks you through every possible cause and solution. Not sure if the flapper or the fill valve is the culprit? Our flapper vs fill valve guide helps you tell them apart.
✍️ About This Review
PTR Editorial Team — Product Reviews. We compare manufacturer specifications, installation requirements, compatibility and available product documentation to help homeowners choose suitable tools and parts. How we review →
Compare five air admittance valves for sinks and bathroom groups by each maker's documented ratings, size, adapter and use. Check your local code first.
Compare five condensate pumps for air conditioners and dehumidifiers by lift, flow, reservoir, safety switch and warranty, using each maker's documents.
Compare five bathroom and shower caulks by surface, joint movement, paintability and water-ready time, using each maker's data sheet.
