How do I know what size toilet seat to buy?

Measure the length of your toilet bowl from the seat bolt holes to the front rim. Under 16.5 inches = round bowl. Over 18 inches = elongated bowl. The width is standard (~14 inches). Most seats label clearly as round or elongated.

Are all toilet seat bolts the same?

Most modern toilets use standard 5.5-inch bolt spacing (measured between bolt hole centers). Some older or European toilets differ — measure yours before buying a replacement.

My old bolt nuts are corroded and won't budge. What do I do?

Spray with WD-40 and wait 10 minutes. Try again with a wrench. If still stuck, use a bolt cutter or hacksaw on the plastic bolt shaft — it's plastic and cuts easily. The new seat comes with new bolts.

What's the difference between cheap and expensive toilet seats?

Cheap seats ($15–$30) use thin plastic that cracks over time. Mid-range ($40–$80) use heavy-duty molded plastic or wood composite with better hinges. Expensive seats ($150+) add features like slow-close hinges, heated seats, or bidet functions.

How to Replace a Toilet Seat (10 Minutes, No Plumber)

Toilet seats crack, stain, and wobble over time. Replacing one is a genuine 10-minute job — you don't need a plumber, any plumbing skills, or more than a wrench and a screwdriver.

What You'll Need

Replacement toilet seat (see FAQ for sizing)
Adjustable wrench or pliers
Flathead screwdriver
WD-40 (optional, for corroded bolts)

Recommended seats:

Kohler Cachet Elongated Toilet Seat — quality build, great hinge hardware, available in multiple colors
Mayfair NextStep Elongated Seat — built-in child seat, great for families
TOTO SoftClose Round Seat — slow-close hinges, very durable

Affiliate disclosure: This page contains affiliate links. We may earn a commission at no extra cost to you.

Step 1: Measure Your Bowl

You need to know if you have a round or elongated bowl before buying. Measure from the center of the bolt holes at the back of the bowl to the front rim:

Under 16.5 inches = round bowl
Over 18 inches = elongated bowl

Also check the bolt hole spacing (center to center) — standard is 5.5 inches. If yours differs, note the measurement.

Step 2: Remove the Old Seat

Lift the plastic caps covering the bolt holes at the back of the seat. These pop up or slide back to reveal the nuts underneath.

Hold the bolt from the top (flathead screwdriver) while you loosen the nut from underneath with a wrench. Turn counter-clockwise.

If the nut is plastic, hand-tighten or use pliers. If it's corroded metal that won't turn, spray WD-40, wait 10 minutes, try again. Last resort: cut through the bolt shaft with a hacksaw.

Lift the seat assembly off.

Step 3: Clean the Mounting Area

Wipe down the hinge area and bolt holes with an all-purpose cleaner. Grime and mildew build up underneath the seat over years and this is your best chance to clean it.

Step 4: Install the New Seat

Most modern seats use a top-tightening system — the bolts are already attached to the seat. Drop the seat into position, aligning the bolt holes with the toilet bowl holes.

From below, thread the nuts onto the bolts by hand, then snug with a wrench. Don't overtighten — plastic bolts strip easily and cracking the porcelain is possible if you really crank. Hand-tight plus a half turn is enough.

Snap the decorative caps down over the bolt holes.

Step 5: Test

Lift and lower the seat a few times to make sure the hinges operate smoothly. Sit on the seat and check that it doesn't shift side to side — if it does, tighten the bolts slightly.

Most new seats come with a front bumper strip that keeps the seat from sliding on the bowl. Make sure it's installed before use.

Slow-Close Hinges: Worth It?

Seats with slow-close hinges cost $10–$30 more but last significantly longer because the soft landing eliminates the impact that cracks standard plastic seats over time. They also eliminate the loud slam that wakes people up at night.

Once you use one, you won't want to go back. Worth the upgrade for any bathroom used daily.

When to Consider an Upgrade

If you're replacing a seat anyway, it's worth considering:

Bidet seats ($30–$80 for basic warm water bidet; $200–$500 for heated seat, dryer, and remote control) — installation takes 20 minutes, requires an outlet nearby
Night light seats — LED strips that glow at night, useful for shared bathrooms
Raised seats — for accessibility, can add 3–4 inches of height without replacing the toilet