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How to Choose a New Toilet Seat

Ask This Old House plumbing and heating expert Richard Trethewey discusses DIY Smarts on the basics of choosing and installing toilet seats.

Steps for choosing a toilet seat

  1. Start by measuring the length of the toilet seat. They come as either round seats at 16” or elongated at 18”. Be sure to buy the correct size seat.
  2. Unscrew the bolts at the back of the toilet seat holding it in place and remove the old toilet seat. Depending on how old the toilet seat is, this may require a screwdriver if the screws are on top of the toilet. If they’re underneath, it’s safest to use a socket wrench to unscrew the bolts.
  3. If the old bolts have become deformed and won’t loosen up, carefully cut them off with a hacksaw. It will be easier to cut them from the top. Place a putty knife underneath the saw to protect the china of the toilet from being scratched.
  4. On the new toilet seat, place the holes on the back of the seat over the holes on the toilet.
  5. Insert the screws that come with the toilet seat into the holes on the toilet. Put the nuts on the underside of the toilet.
  6. Tighten the screws with a flathead screwdriver.


Richard distinguishes between Round (16”) and Elongated (18”) toilet seats. Replacement seats must match the existing toilet seat.

The seat with a potty training seat built in is the NextStep Children’s Toilet Seat, manufactured by Bemis Manufacturing Company.

The elevated seat with grab bars is manufactured by Glacier Bay and is available at home centers.

The artistic seats that Richard showed are available in many styles and can be found at online retailers.

The high-tech toilet seat with the bidet that Richard demonstrated is the Advanced Clean AC 2.0 Spalet Bidet Seat, manufactured by American Standard.

(All products above via The Home Depot).

Shop Toilet Seats at The Home Depot