Toilet seats come in two shapes and they are not interchangeable. Buy the wrong one and it either overhangs the bowl or leaves a gap at the front — and you find out after you’ve thrown the packaging away.
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Measure the bowl, not the old seat
Old seats warp and the hinges shift, so measuring the seat you’re replacing can mislead you. Measure the bowl:
- Put the tape at the center of the two seat-bolt holes at the back of the bowl.
- Run it forward to the outside front edge of the bowl rim.
- Read the number.
- About 16-1/2 inches → ROUND.
- About 18-1/2 inches → ELONGATED.
There’s roughly two inches between the two standards, so the measurement is not a close call. If you land between them, measure again — you’ve probably started from the wrong point.
Also worth checking: the width at the widest point (both shapes are commonly around 14-1/2 inches, but compact and specialty bowls exist) and the bolt-hole spacing, which is a standard 5-1/2 inches on nearly everything.
Slow-close: worth it or gimmick?
Worth it, and for a practical reason rather than a comfort one. A lid that slams is a lid being cracked slowly, and the hinges take the shock too. Slow-close hinges remove that entirely, and the noise difference matters in a house where someone is asleep.
The honest caveat: the mechanism is the part that eventually wears. A cheap slow-close seat that goes stiff or stops closing gently in two years is worse value than a good standard seat. Buy a decent one.
- Bemis 7300SLEC slow-close elongated seat with easy-clean hinges — soft-close lid, and the quick-release hinges let you take the whole seat off for proper cleaning, which is the feature you appreciate most after a year.
Quick-release hinges are the underrated feature
The area around the seat bolts is the hardest part of a toilet to clean, and on a fixed seat it never really gets done. Quick-release hinges pop the seat off in a second so you can clean the bowl rim properly and put it back. If you’re choosing between two similar seats, this is the tiebreaker.
Fitting it
- Old bolts often won’t turn. Plastic ones snap, metal ones corrode. A little penetrating oil and patience beats brute force; if a metal bolt is seized, cutting it is faster than rounding it off.
- Snug, not tight. Overtightening cracks the china around the bolt holes — an expensive way to fit a cheap part.
- Sit on it before final tightening to check it’s centered and doesn’t rock.
- Re-snug after a week. New seats settle, and a wobbling seat is just a loose nut.
If the seat isn’t really the problem
A seat that keeps loosening, sits crooked, or rocks despite tight bolts is sometimes telling you about the toilet rather than the seat — a warped bowl rim, or a toilet that moves on the floor. If the whole fixture rocks, that’s a flange or shim issue, and a moving toilet eventually breaks its wax seal: see toilet leaking at base and toilet flange too low.
Replacing the whole toilet instead? Get the rough-in measurement first, and the shape decision is covered in round vs elongated. Shopping seats: best toilet seats. Considering a bidet seat instead of a plain one: bidet toilet seats.
FAQ
How do I know if my toilet seat is round or elongated?
Measure from the center of the seat-bolt holes to the outside front edge of the bowl. About 16-1/2 inches is round; about 18-1/2 inches is elongated. There’s roughly two inches between the standards, so it isn’t a close call.
Are toilet seat bolt holes a standard spacing?
Yes — about 5-1/2 inches center to center on nearly every residential toilet. It’s the bowl shape, not the bolt spacing, that decides which seat fits.
Is a slow-close toilet seat worth it?
Yes, mainly because a slamming lid damages both the lid and the hinges over time. Buy a decent one though — the soft-close mechanism is the part that wears, and a cheap one that fails in two years is worse value than a good standard seat.
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