How to Measure Your Toilet Seat

Before buying a bidet attachment or bidet seat, you need to confirm one thing: that it will actually fit your toilet. Luckily, measuring takes about two minutes.

What You’ll Need

• A tape measure or ruler

Step 1: Measure the Bolt Spacing

This is the most important measurement for bidet compatibility.

• Locate the two bolts that hold your toilet seat in place

• Measure from the center of one bolt to the center of the other

• Most toilets measure 5.5 inches, which fits the vast majority of bidet attachments and seats

If your spacing is unusual, compatibility may be limited.

Step 2: Measure the Bowl Shape (Round vs. Elongated)

Bidet seats must match your bowl shape.

Measure from:

• The center of the seat bolts

• To the front edge of the bowl

Results:

• Round toilets: about 16.5 inches

• Elongated toilets: about 18.5 inches

Bidet attachments usually work with both, but bidet seats do not.

Step 3: Check Tank and Plumbing Clearance

For bidet attachments:

• Make sure there’s space between the toilet tank and seat hinges

• Confirm you have access to the water supply valve

For warm-water bidets:

• You’ll also need access to a nearby sink for the water line

Why This Matters

A bidet that doesn’t fit can:

• Sit unevenly

• Shift during use

• Be impossible to install properly

A quick measurement ensures a clean install and a better experience.

The Takeaway

To see if a bidet will fit your toilet, measure:

• Bolt spacing

• Bowl length and shape

• Clearance around the tank and water supply

A couple of minutes now saves a lot of hassle later.