A toilet seat is the part of the bathroom you touch most and think about least, until it cracks, wobbles, yellows or slams. Replacing it is a 15-minute job with a screwdriver, and a new soft-close seat is one of the cheapest upgrades that makes a bathroom feel new. The only tricky parts are buying the right size and dealing with old bolts that have rusted solid. This guide covers both, plus what to know if you are considering a bidet seat.
Key takeaways
- Measure from the seat bolts to the front edge of the bowl: about 16.5" = round, about 18.5" = elongated. Bolt spacing is 5.5" on nearly every toilet.
- Soft-close seats cost $30–$80 and stop slamming forever. Worth it in any bathroom with children.
- Rusted bolts: penetrating oil, then a hacksaw or oscillating tool if they will not turn. Ten minutes, no drama.
- Top-fix seats install from above (needed on many one-piece and skirted toilets). Bottom-fix seats have nuts under the rim.
- Bidet seats need an outlet within reach and a standard 7/8" supply connection. Measure before ordering.
Step 1: Measure your toilet
There are only two bowl shapes in North America, and the seat has to match.
| Measurement | Round bowl | Elongated bowl |
|---|---|---|
| Bolt holes to front edge of bowl | 16.5" (42 cm) | 18.5" (47 cm) |
| Bolt hole spacing (centre to centre) | 5.5" (14 cm) | 5.5" (14 cm) |
| Bowl width | ~14" | ~14" |
| Typical use | Older homes, small powder rooms | Most toilets sold today |
Measure with the seat still on: from the centre of the hinge bolts to the front tip of the bowl (not the seat). If you get something in between, like 17", measure again; a round seat on an elongated bowl leaves an exposed rim, and an elongated seat on a round bowl overhangs.
Also note whether you can reach under the rim behind the bowl. On skirted and many one-piece toilets you cannot, and those need a top-fixing seat that tightens from above.
Step 2: Choose the seat
Plastic (polypropylene)
$15–$40. Light, easy to clean, will not absorb moisture. Cheap ones flex and yellow; better ones are thick and UV-stable.
Duroplast / thermoset
$40–$100. Hard, scratch-resistant, feels like porcelain. The material used on most European and premium seats. Best long-term value.
Wood (enamelled MDF)
$30–$70. Warm and solid, but the coating chips and the core swells if water gets in. Avoid in kids' bathrooms.
Bidet seat
$300–$3,000. Heated seat, warm-water wash, dryer, deodorizer. Needs a GFCI outlet nearby. See our bidet guide.
Features worth paying for
- Soft-close hinges. The lid and seat lower slowly. No slamming, no chipped porcelain, no waking the house at 2 a.m.
- Quick-release hinges. The seat lifts off the hinge posts for cleaning around the bolts, which is where the smell lives.
- Stainless-steel or brass bolts rather than plated steel, which rusts in five years.
- Non-slip bumpers that keep the seat from sliding sideways on the bowl.
Step 3: Remove the old seat
- Pry open the plastic bolt caps at the back of the seat with a flat screwdriver.
- Hold the nut under the bowl rim with pliers or a small wrench and turn the bolt head counter-clockwise with a screwdriver. Plastic nuts often turn by hand.
- Lift the seat off. Clean the area around the holes with a disinfecting cleaner; it is usually the dirtiest spot on the toilet.
If the bolts are rusted or spin
- Bolt spins but does not loosen: the nut underneath is turning with it. Grip the nut with locking pliers while you turn the screw.
- Rusted solid: spray penetrating oil on the nut from below, wait 15 minutes, try again. Repeat once.
- Still stuck: cut the bolt. Slide a thin hacksaw blade or an oscillating multi-tool between the hinge and the porcelain, protecting the bowl with a strip of cardboard or a putty knife. It takes two minutes. Then lift the seat and push the remains through.
- Bolt head is stripped: a small pair of locking pliers on the head from above, or cut it as above.
Step 4: Install the new seat
Bottom-fix (standard)
- Set the seat on the bowl and drop the bolts through the hinges and the holes in the porcelain.
- Thread the nuts on from below by hand. Some seats use a rubber sleeve and washer; put the washer between the nut and the porcelain.
- Centre the seat on the bowl and check the front edge lines up. Hinges usually have some side-to-side and front-to-back adjustment.
- Tighten the nuts snug with pliers, alternating sides. Do not overtighten: you can crack the porcelain or strip the plastic.
- Snap the bolt caps closed.
Top-fix (for skirted and one-piece toilets)
- Push the rubber expansion anchors into the bowl holes from above.
- Set the hinge plates over the anchors and tighten the screws from above. As the screw tightens, the anchor expands inside the hole and grips.
- Slide or click the seat onto the hinge plates, adjust the position, and tighten the locking screws or caps.
Adding a bidet seat: what to check first
- Power. Electric bidet seats need a grounded GFCI outlet within about 1.2 m (4 ft) of the toilet. Extension cords are not a safe permanent solution. Non-electric bidet attachments need no power.
- Water. The supply line to the tank uses a standard 7/8" ballcock fitting. The bidet's T-valve fits between the shut-off and the tank.
- Bowl shape. Bidet seats come in round and elongated. Elongated fits most modern toilets, and on some one-piece toilets the tank shape limits which seats fit; check the manufacturer's fit list.
- Clearance. The seat needs about 1" between the bolt holes and the tank for the control pod, or use a remote-control model.
When the toilet, not the seat, is the problem
A new seat will not fix a bowl that is chipped at the rim, a toilet that rocks on the floor, or a 20-year-old 13 L flush. If you are already spending an hour on the seat, look at the toilet honestly. Modern one-piece toilets ship with a soft-close, quick-release seat included, and the whole thing costs about the same as a premium bidet seat alone.
Toilets and bidet seats at MyBath
One-piece toilets with soft-close seats, Toto Washlets and integrated smart toilets. Delivered across Ontario, free on orders over $600.
Frequently asked questions
Are toilet seats universal?
Almost. Bolt spacing is 5.5" on nearly all toilets, so the only choice is round or elongated. Some designer toilets use proprietary seats; check the brand if the bowl is an unusual shape.
How do I know if my toilet is round or elongated?
Measure from the seat bolts to the front edge of the bowl. About 16.5" is round; about 18.5" is elongated.
How do I remove toilet seat bolts that will not come off?
Hold the nut underneath with locking pliers while turning the screw. If it is rusted, use penetrating oil, then cut the bolt with a hacksaw blade or oscillating tool while protecting the porcelain.
Are soft-close toilet seats worth it?
Yes. They cost $15–$30 more than a basic seat, eliminate slamming, and protect the bowl from chips. Most also have quick-release hinges for easier cleaning.
How tight should toilet seat bolts be?
Snug plus a quarter turn. The seat should not shift when you push it sideways, but overtightening cracks porcelain and strips plastic nuts.
Can I put a bidet seat on any toilet?
On most. You need the right bowl shape, a nearby GFCI outlet for electric models, and enough clearance between the bolt holes and the tank. Check the manufacturer's fit guide for one-piece toilets.
