Best Toilet Flappers
A toilet that won't stop running almost always comes down to one cheap part: the flapper. That's the rubber seal at the bottom of the tank that lifts when you flush and drops back to hold water. When it warps, hardens, or gets eaten away by chlorine, water leaks past it and your toilet runs — sometimes wasting hundreds of gallons a day.
The good news is a flapper is one of the easiest and cheapest repairs in the house. Most cost under $15, install in a few minutes with no tools, and fit a wide range of toilets. The trick is matching the right size and style to your tank.
We curated the five flappers below from the brands plumbers actually trust — Korky and Fluidmaster — covering 2-inch and 3-inch valves, plus adjustable and hard-water options. This roundup is research-based, not a paid hands-on test, so we focus on fit, materials, and what real owners report.
| # | Pick | Price | Rating | |
|---|---|---|---|---|
| 1 | Best Overall Korky 100BP Ultra High Performance 2-Inch Universal Toilet Flapper The 2-inch flapper that fits almost everything, adjusts its flush, and shrugs off chlorine and hard water. |
$8–$14 | ★★★★★ 4.8 | Check price |
| 2 | Best Budget Korky 54BP 2-Inch Toilet Tank Flapper with Stainless Chain The plain red-rubber flapper plumbers have trusted since 1954 — cheap, simple, and it just works. |
$6–$10 | ★★★★★ 4.6 | Check price |
| 3 | Best Adjustable Fluidmaster 502P21 PerforMAX Universal Adjustable 2-Inch Flapper A dial-tuned 2-inch flapper with a rigid frame that lets you set the exact flush you want. |
$8–$13 | ★★★★★ 4.6 | Check price |
| 4 | Best for Hard Water Korky 2017BP Ultra 2X High Performance 2-Inch Flapper Korky's toughest 2-inch flapper, built with rubber rated twice as strong to beat hard water and bleach. |
$9–$16 | ★★★★★ 4.7 | Check price |
| 5 | Best for 3-Inch Valves Korky 3060BP Universal 3-Inch Toilet Flapper The universal answer for big 3-inch flush valves on modern high-efficiency toilets. |
$10–$18 | ★★★★★ 4.5 | Check price |
Korky 100BP Ultra High Performance 2-Inch Universal Toilet Flapper
Key features: 2-inch universal fit · Adjustable dial controls water per flush · Made-in-USA Chlorazone red rubber · Resists chlorine, hard water, and well water · Tool-free clip-on install
Pros
- Fits the widest range of common toilets, so you rarely need to know your exact model
- Dial lets you fine-tune flush volume to stop running without weak flushes
- Rubber holds up to bleach tablets and hard water that crack cheaper flappers
- Goes on in a couple of minutes with no tools
Cons
- Single flapper, so a bulk household repair costs more than a multipack
- The adjustment dial takes a little trial and error to dial in
Who it's for: Anyone fixing one running 2-inch toilet who wants a single part that just fits and lasts. The safe default pick if you're not sure which flapper you need.
Korky 54BP 2-Inch Toilet Tank Flapper with Stainless Chain
Key features: 2-inch universal fit · Chlorazone red rubber · Includes stainless steel chain · Non-adjustable, simple seal · Made in USA
Pros
- One of the lowest prices you'll find from a name brand
- Dead-simple design with very little to go wrong
- Comes with a rust-proof stainless chain so you replace the whole assembly
- The decades-old plumber standard for plain 2-inch valves
Cons
- No flush-volume adjustment, so you can't fine-tune it
- Not ideal for newer toilets that need a specially shaped flapper
Who it's for: Budget-minded DIYers and landlords with older or standard 2-inch toilets who want a no-frills fix that's been proven for decades.
Fluidmaster 502P21 PerforMAX Universal Adjustable 2-Inch Flapper
Key features: 2-inch universal fit · Adjustment dial for water per flush · Solid (rigid) frame resists warping · Corrosion-resistant materials · 5-year warranty
Pros
- Easy dial lets you turn flush volume up or down by hand
- Rigid frame stops the bend-and-twist that makes soft flappers leak
- Backed by a 5-year warranty
- Strong fit on modern 1.28 and 1.6 gallon water-saving toilets
Cons
- You have to set the dial correctly or it can flush weak or run long
- Rigid frame can be slightly fussier to seat than a plain soft flapper
Who it's for: People with a water-saving 1.28 or 1.6 GPF toilet who want to dial in the exact flush volume and stop both running and weak flushes.
Korky 2017BP Ultra 2X High Performance 2-Inch Flapper
Key features: 2-inch universal fit · Chlorazone II rubber rated 2x stronger · Adjustable flush volume · Resists chlorine, hard water, and well water · Made in USA
Pros
- Upgraded rubber is built to outlast standard flappers in harsh water
- Handles in-tank bleach tablets better than most
- Adjustable so you can still tune the flush
- Same easy clip-on install as Korky's standard flappers
Cons
- Costs a bit more than a basic flapper
- Overkill if your water is soft and you don't use tank tablets
Who it's for: Homeowners on hard or well water, or anyone who uses chlorine tablets in the tank and is tired of replacing flappers that go stiff and leak.
Korky 3060BP Universal 3-Inch Toilet Flapper
Key features: 3-inch universal fit · Replaces most large 3-inch flappers · Long-lasting Korky rubber · Tool-free install · Made in USA
Pros
- Solves the harder-to-find 3-inch size that many newer toilets use
- Universal design covers most large-valve toilets
- Korky rubber resists chlorine and hard water
- Quick clip-on replacement, no tools
Cons
- Only for 3-inch valves — will not fit a standard 2-inch toilet
- Costs a little more than common 2-inch flappers
Who it's for: Owners of newer high-efficiency or larger-tank toilets that use the bigger 3-inch flush valve and need a universal replacement instead of a brand-specific part.
What matters when choosing a bidet seat
- Get the size right (2-inch vs 3-inch). This is the one thing you cannot guess. Most older and standard toilets use a 2-inch flapper; many newer high-efficiency toilets use a larger 3-inch one. Pull your old flapper and measure across the seal opening, or look at the flush valve. A 2-inch flapper will never seal a 3-inch valve, and vice versa.
- Rubber quality and chlorine resistance. Cheap rubber goes stiff and warps, especially if you drop bleach tablets in the tank or have hard water. Look for chlorine-resistant materials like Korky's Chlorazone rubber or Fluidmaster's corrosion-resistant builds. Better rubber is the single biggest reason one flapper lasts years and another fails in months.
- Adjustable vs. fixed flush. Adjustable flappers have a dial or band that lets you set how much water leaves per flush. That's handy for stopping a running toilet without killing flush power, or for saving water on a 1.28 or 1.6 GPF model. Fixed flappers are simpler and cheaper but offer no fine-tuning.
- Universal fit vs. brand-specific. Universal flappers are designed to fit most major brands (American Standard, Kohler, TOTO, and more), so you don't need to track down your exact toilet model. A few toilets — certain Kohler Class Five models, for example — flush best with a flapper made for that valve, so check compatibility if a universal one seals poorly.
- Chain and install hardware. A good flapper that comes with a stainless steel chain saves you from reusing a rusty one. The chain length matters too: too long and it gets stuck under the flapper, too short and the seal won't close. Most quality flappers clip on in minutes with no tools.
How we ranked these
We built this list around three things that decide whether a flapper actually fixes your toilet: correct sizing for common valves, rubber that resists chlorine and hard water, and honest install simplicity. We leaned on the two brands plumbers rely on — Korky and Fluidmaster — and confirmed every pick is a current, purchasable Amazon listing matched to the exact model. We deliberately spread the picks across needs (overall, budget, adjustable, hard water, and 3-inch valves) so most readers find their match without overlap. This is a research-curated roundup, so ratings reflect fit, materials, brand track record, and aggregated owner feedback rather than our own teardown.
Frequently asked questions
How do I know if I need a 2-inch or 3-inch flapper?
Turn off the water, flush to empty the tank, and look at the round opening the flapper covers — that's the flush valve. Measure across it. About 2 inches means a standard 2-inch flapper; about 3 inches means you need a 3-inch flapper, common on newer high-efficiency toilets. When in doubt, bring the old flapper to compare. The wrong size will not seal.
How do I replace a toilet flapper?
Shut off the water at the valve behind the toilet and flush to drain the tank. Unhook the old flapper's chain from the flush lever, then slide or unclip the flapper off the overflow tube's ears or pegs. Snap the new flapper on the same way, clip the chain to the lever with a little slack, turn the water back on, and test a flush. The whole job usually takes under five minutes with no tools.
Which flapper should I choose for my situation?
For most 2-inch toilets, start with the Korky 100BP — it fits nearly everything and adjusts. On a tight budget with an older standard toilet, the Korky 54BP is the proven cheap fix. Want to fine-tune flush volume on a water-saving toilet? Go Fluidmaster 502P21. Hard or well water or bleach tablets in the tank? The Korky 2X (2017BP) uses tougher rubber. Newer toilet with a big valve? You need the 3-inch Korky 3060BP.
Why does my toilet keep running even after a new flapper?
A flapper fixes most running toilets, but not all. Check the chain isn't too long (it can get pinned under the flapper) or too short (it holds the flapper open). Make sure the flapper seats flat with no mineral buildup on the valve seat — wipe it clean. If water still trickles, the issue may be the fill valve or a cracked overflow tube, not the flapper.
Can a leaking flapper really raise my water bill?
Yes, and often more than people expect. A flapper that doesn't seal lets water slowly drain from the tank, triggering the fill valve to top off over and over. A bad leak can waste hundreds of gallons a day. Since the part costs under $15 and installs in minutes, replacing a worn flapper is one of the highest-payback repairs in the house.