Replacing a toilet seat is the most accessible home repair on this list. It takes 10 minutes, requires one adjustable wrench, and involves zero plumbing knowledge. Knowing how to replace a toilet seat is mostly about measuring correctly before buying and not overtightening the plastic bolts during installation. Get those two things right and the whole job is done before you would have finished scheduling a plumber.
Measure before you buy anything
There are two standard toilet bowl shapes: round and elongated. Buying the wrong one means returning it, because a round seat on an elongated toilet overhangs the front in a way that looks wrong and an elongated seat on a round toilet does not sit flush at the back. Measure before you shop.
Measure from the center of the bolt holes at the rear of the toilet to the front edge of the bowl, not the front of the seat, but the porcelain bowl itself. A measurement of 16.5 inches means round. A measurement of 18 to 18.5 inches means elongated. Take a photo of this measurement and the existing seat hinge area when you go shopping so you have a reference if you have questions about fit.
Most replacement seats are available in both shapes at any hardware store or on Amazon with shape clearly specified in the product title. If you are upgrading to a soft-close seat at the same time, confirm the shape in the product specs before adding to cart. Soft-close hinges on Amazon are available in both shapes starting around $25 and are worth the upgrade if the current seat slams.
Remove the old seat
Look at the rear of the existing seat where the hinges meet the toilet. There are two plastic caps that snap or screw into place over the mounting bolt heads. Pry these open with a flathead screwdriver or pop them up with your thumbnail. They expose either a bolt head on top or just the top of the bolt shaft, depending on the seat design.
Reach underneath the toilet bowl rim and feel for the nuts that thread onto the mounting bolts. They are typically plastic wing nuts or hex nuts. An adjustable wrench works on the hex nut style. The wing nut style you may be able to turn by hand if there is enough clearance. Hold the bolt steady from the top while turning the nut from below if the bolt spins without the nut moving.
Once both nuts are off, lift the seat straight up and off. Wipe the hinge mounting area on the toilet with an all-purpose cleaner before the new seat goes on. Old seats leave a ring of residue around the mounting holes that is easier to clean now than after the new seat is installed.
Install the new seat
Drop the new mounting bolts down through the hinge holes on the new seat and into the corresponding holes in the toilet. Most new seats have the bolts pre-attached to a hinge plate that drops into position as one unit. Lower the seat into place so the hinge plate sits flat against the toilet and the seat and lid rest evenly on the bowl.
Thread the nuts onto the bolts from underneath by hand until snug. Then use an adjustable wrench to tighten one additional half turn, alternating between the two sides to keep the seat centered. Stop at a half turn past hand-tight. Do not keep tightening. Plastic toilet seat bolts crack under too much torque and porcelain can crack around the mounting holes if you apply significant force. The seat is secure when it does not shift sideways when you press the edges. It does not need to feel immovable from below.
Snap the plastic bolt caps back into position over the mounting nuts. Test the seat and lid: they should open and close smoothly without wobbling. If the seat shifts to one side, one nut may be tighter than the other. Even out the tension by backing off the tighter side slightly.
While you are under the toilet
Getting under the toilet tank area is a good time to check a few other things. Inspect the supply line connection at the base of the tank for any mineral deposits or moisture that would indicate a slow leak. Check that the shut-off valve turns freely. If the toilet runs periodically or you can hear it refilling when it has not been flushed, the flapper is likely the cause. The guide on how to fix a running toilet flapper covers that repair, which is another 15-minute project that saves money on the water bill.
If the toilet drains slowly or you occasionally need to manage a clog, the guide on how to unclog a toilet without a plunger gives you effective alternatives when the plunger is not available. And the guide on how to replace a bathroom faucet covers the next level up in bathroom plumbing upgrades if you are doing a broader bathroom refresh.
Include a toilet seat check on your spring home maintenance checklist. Toilet seats loosen over time and a loose seat is both annoying and a sign the mounting bolts may be ready to crack. Tightening twice a year and replacing when the finish deteriorates keeps the bathroom looking well-maintained without any real effort.
For the complete list of tools that make projects like this straightforward, the best home tool kit for beginners is a good reference. And if you are working through a broader list of home repairs and want a structured approach to prioritizing them, the Broke Mom Home Reset is a $17 guide worth picking up.
