Repair when Not in Use


Determining Whether You Have a 2" or 3" Flush Valve and Flapper

One of the biggest challenge to finding the right flapper for your toilet is to determine which size of flapper will fit your toilet. Most toilets will have a 2-inch drain or a 3-inch drain. Fluidmaster manufactures a standard or universal size of flush valves with flappers and are among the most common flush valves to be used. All though there are many different types of flush valves most flush valves are interchangeable and depend on the size of the ceramic flush hole that is bored through the tank by the porcelain manufacturer.

Fluidmaster’s Flush Valves use flappers to connect to the flush valve and can be easily replaced by snapping them off and on to the flush valve. These flappers are labeled as 2 inch or 3 inch for their corresponding flush valve size to make it easier for you to select the correct flapper.

The simplest way to determine which Fluidmaster flush valve and flapper to use is to measure the flapper that is already on the flush valve. To identify what size is needed measure the width of the flapper from end to end. If the flapper measures 3 inches across select a 2 inch flapper (like the 502 Fluidmaster model) if the flapper measures 4 inches across select a 3 inch flapper (like the 5403 Fluidmaster model).

Fluidmaster toilet flapper
Fluidmaster Flapper

The 507AK – 2″ Flush Valve comes with the 2″ 502 Flapper:

Toilet Flush Valve
Fluidmaster Toilet Flush Valve

The 540AKR – 3′ Flush Valve comes with the 3″ 5403 Flapper:

Flush Valve for Toilets
Fluidmaster Flush Valve

To view the entire range of Fluidmaster Flappers, please click here: Fluidmaster Toilet Flappers

To solve ALL your toilet problems, consider either the 2″ Everything Toilet Repair Kit or if you have a 3″ flush and flapper consider the 3″ Everything Toilet Repair Kit

To download our free guide to fix common toilet problems please click here: Fluidmaster Toilet Repair Guide


Frequently Asked Questions

  • What is a toilet flapper?

  • Are all toilet flappers universal?

  • Why is my toilet flapper not closing?

  • How do I know if the flapper is the reason for the leak from the tank into the bowl?

  • Why does the toilet flapper drop so fast?