Toilet Parts Size Chart

Every replaceable toilet part comes in a standard size — measure first and this chart converts the measurement into the right part.

Flappers come in two diameters only: 2-inch (50 mm) and 3-inch (75 mm). The size belongs to the flush valve opening in the bottom of the tank, not to the flapper itself, so measure across that opening with a ruler before buying a replacement.

Fill valves fit most tanks by adjustment rather than by size, but they are judged by performance: a healthy valve refills a 3.8 L (1 gallon) tank in 90-150 seconds. A valve that leaves the tank refilling past 3 minutes is failing — or the flapper downstream of it is leaking.

Supply lines are 3/8-inch (9.5 mm) braided stainless steel. The replacement rule is strict: every 5 years, or immediately at the first visible bulge in the braid, because a bulge means the inner hose has already let go.

Tank-to-bowl bolts are 1/4-inch (6 mm) in diameter and corrode after 8-10 years in the wet environment inside the tank. A full reseal — bolts, washers and gasket — takes 45-60 minutes with the tank off.

Threaded supply connections seal with PTFE plumber's tape: 3-5 turns around 1/2-inch (12.7 mm) threads, wrapped in the direction the nut tightens. More tape is not better — beyond five turns the nut can bind before it seals.

• Flapper: 2 in (50 mm) or 3 in (75 mm) — match the flush valve opening.
• Fill valve: healthy refill is 90-150 s for a 3.8 L tank.
• Supply line: 3/8 in (9.5 mm) braided stainless, 5-year life.
• Tank bolts: 1/4 in (6 mm), expect corrosion by 8-10 years.
• Thread seal: 3-5 turns of PTFE on 1/2 in (12.7 mm) threads.

Further reading

• Unclog a Slow Drain in 4 Steps
• Fix a Dripping Faucet