How to fit or replace a toilet seat
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Toilet seats are held by two bolts through the ceramic pan — either top-fixing (bolt through the seat hinge from above) or bottom-fixing (nut accessed from underneath the pan rim). Most modern seats use top-fixing for easy fitting.
Measure your toilet pan before buying a replacement: you need the distance between the two fixing holes (typically 150mm for most UK pans), the overall length of the pan from fixing holes to the front, and the shape (round, D-shape, or square). Take photos of your existing seat and pan to the shop.
Remove the old seat: on top-fixing seats, unscrew the plastic caps on the hinges, remove the bolts (often requiring a screwdriver from above and a spanner underneath), and lift off the seat and hinge assembly.
Clean the fixing hole area thoroughly — limescale and mould often accumulate under the hinge plates. This is your chance.
Fit the new seat: insert the bolts through the hinge fixings into the pan holes. For top-fixing seats, tighten the nuts from below until the seat is secure but do not over-tighten as this can crack ceramic. For soft-close seats, check the hinge dampers are set correctly — a dial on the hinge controls the closing speed.
Confirm the seat closes centrally over the pan and the lid closes flat. Most modern seats have a height and alignment adjustment at the hinge — use these to align correctly before final tightening.
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Frequently asked questions
How do I know what size toilet seat to buy?
Measure the distance between the two hinge bolt holes at the back of the pan — standard UK spacing is 155mm centre-to-centre. Also note whether your pan is round or elongated (D-shaped). Most toilet seats are labelled with the fixing dimensions on the packaging.
Are toilet seats universal?
Not quite — while most UK pans use standard 155mm hole spacing, the overall shape (round vs elongated) and the seat width vary. Many modern seats have adjustable hinge positions to fit a range of pans. If in doubt, take a photo of your pan from above and check compatibility before buying.
How long does fitting a toilet seat take?
Fitting a new toilet seat takes 15–30 minutes with a basic screwdriver. Most modern seats click directly onto hinge bases fixed to the pan, making removal and refitting tool-free. Only older pan designs with wing nuts under the rim require any awkward reaching.