How to Measure Your Toilet Seat (Step-By-Step Guide)

1. Identify Your Toilet Shape

Toilets typically come in two shapes: round and elongated. A round toilet bowl resembles a perfect pizza pie, while an elongated bowl is longer and more oval-shaped.

Using the wrong size seat is immediately noticeable—a round seat on an elongated bowl will leave part of the bowl exposed, while an elongated seat on a round bowl will hang over the edge.

Here's how to measure your toilet seat to ensure you get the right size the first time.

2. Gather Your Tools

You will need:

• A measuring tape
• Pen and paper or your phone notes app
• A screwdriver/wrench to remove your old seat
• All-purpose cleaner to shine your throne

3. Measure the Seat Length

Remove your existing toilet seat. You might need to unscrew it or simply pop it off if it has a quick-release design.

Measure from the center of the bolt spread (where the seat attaches to the toilet) to the outer front edge of the toilet bowl.

• If your toilet bowl is approximately 16 ½ inches long, it is round.
• If your toilet bowl is approximately 18 ½ inches long, it is elongated.

If your toilet length is different, you may have a custom or specialty toilet. Continue reading to learn how to measure the rest of your toilet for accurate sizing.

4. Measure the Seat Width

Measure the widest point of your toilet from lip to lip. A standard toilet bowl typically measures around 14 ½ inches, though there can be slight variations between brands. Note the exact width for your online search or when visiting the hardware store.

5. Measure the Bolt Spread

For a standard US toilet, the bolt spread is likely 5 ½ inches. Measure from the center of the left bolt hole to the center of the right bolt hole to confirm.

*Apologies for using "bolt hole."

Measuring Your Toilet Seat for a Bidet

Most modern bidet attachments are adjustable to fit standard toilets. Check the specifications of the bidet attachment to ensure the control panel fits between your toilet and the wall. Measure the distance from the middle of the bolt holes to the tank for adequate clearance.

If upgrading to an electric bidet seat, choose between a round or elongated seat and follow these length guidelines:

• ~16 ½ inches (420mm) = round bidet seat
• ~18 ½ inches (470mm) = elongated bidet seat

Consider factors like having a skirted toilet (smooth base surface) or a flushometer (tankless toilet), which may need special adapters and additional connections. Always check compatibility before purchasing or consult with customer service experts.

Knowing how to measure a toilet seat may not be glamorous, but it will save you from multiple hardware store trips and ensure a proper fit for your bidet. This will save you time and prevent discomfort from a poorly fitting seat.

Frequently Asked Questions

What are the standard toilet sizes? Standard US toilets typically measure 14 ½ inches wide x 16 ½ inches long for a round seat or 14 ½ inches wide x 18 ½ inches long for an elongated seat.

What is the difference between elongated and round toilet seats? Round seats are more circular and shorter in length, while elongated seats are longer and more oval-shaped. Both types usually have the same width.

How do I know my toilet seat size? Remove your toilet seat and measure your toilet bowl. Use a tape measure to determine the length (from the middle of the bolt holes to the outer front edge of the bowl) and width (at the widest point from lip to lip).