Toilet Rocking or Wobbly? Plastic Shims Fix It in 10 Minutes
A rocking toilet sits on an uneven floor or on loose bolts. Snug the bolts first; if it still moves, plastic shims lock it steady in about 10 minutes.
By Jamilur Rahman Updated November 5, 2026 · 7 min read
- Time
- 10-20 min
- Cost
- Under $20
- Difficulty
- Easy
In this guide
Quick answer
A toilet rocks because the floor is not flat under it, or because the closet bolts have loosened. Snug the bolts a little at a time first. If it still moves, slide plastic shims into the gap, trim them flush and caulk the base. It takes about 10 minutes and the toilet stays where it is.
Free fix vs. permanent fix
Snug the closet bolts
- Pop off the plastic bolt caps
- Tighten each nut a little at a time, alternating sides
- Stop as soon as the toilet feels firm, because porcelain cracks if you force it
- Push each corner to check for movement
How long it lasts: As long as loose bolts were the only problem. If the floor is uneven, the rocking comes back.
Plastic toilet shims
If the floor is uneven, the bolts cannot fix it. Tightening only pulls the bowl down onto the high spot and risks a crack. Shims fill the gap so the weight is carried evenly, the bowl stops moving, and the seal at the floor stays intact.
How long it lasts: Years. Plastic does not rot or squash the way wood or cardboard does.
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What you'll need
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Adjustable wrench or socket set
For the nuts on the closet bolts
You have it -
Utility knife
Trims the shims flush with the base
You have it - Our pick Illustration
Plastic toilet shims
Wedge-shaped, in a few sizes
- Illustration
Silicone caulk
Seals the sides and front after shimming
- Illustration
Toilet closet bolt set
Only if the old bolts are rusted or stripped
- Illustration
Wax ring seal kit
Only if the seal under the bowl has failed
Why it happens
An uneven floor
Tile, old subfloors and settled houses are rarely flat. A gap of even an eighth of an inch under one side of the base lets the bowl rock.
Loose closet bolts
Two bolts at the base hold the toilet to the floor flange. Daily use loosens the nuts, and the bolts can corrode. The back corners are the usual culprits.
A flange that sits too high or too low
After new flooring goes in, the flange can end up above or below the finished floor. The bowl then rests on the seal instead of the floor, which can make it rock and later leak.
A soft or rotted subfloor
A slow leak over months can soften the wood under the toilet. If the floor feels spongy near the base, shims will not cure it, and the floor needs repair.
Try this first (free)
Do these in order, starting with the simplest.
-
1. Pop off the bolt caps and check the nuts
Tool used: Adjustable wrench or socket setLift the plastic caps at the base with a flat screwdriver. If a nut turns easily, it is loose. Rust on the bolt or nut is a sign it may need replacing.
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2. Snug, do not crank
Tool used: Adjustable wrench or socket setTighten each nut about a quarter turn, alternating sides, until the bowl stops moving. Over-tightening can crack the porcelain. If a nut keeps spinning without tightening, the bolt is stripped or the flange is broken.
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3. Find the gap
Push on each corner of the bowl and watch where the base lifts. A small level across the rim shows if it tilts front to back or side to side. The gap shows where the shims go.
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4. Slide in the shims
Tool used: Plastic toilet shimsPush a shim into each gap until the rocking stops, tapping it in gently. Use as few as work, and recheck the level. Then snug the nuts one last time, just until firm.
IllustrationCheck price on AmazonTool for this step
Plastic toilet shims · Wedge-shaped, in a few sizes
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5. Trim and caulk
Tool used: Utility knifeScore the part of each shim sticking out with a utility knife and snap it off flush with the base. Run a thin bead of caulk around the sides and front. Many plumbers leave a small gap at the back, so a leak would show. Let the caulk cure before using the toilet.
When free fixes aren't enough
If tightening alone stopped the rock, you are done. If it returns, the floor under the base is uneven, and shims are the fix, because bolts can only pull the bowl onto the high spot. Stop and call a plumber if the floor feels soft, if you see water at the base or smell sewage, or if a bolt spins or snaps. Those jobs need the toilet lifted and the seal replaced, and a wax ring that has been rocked for months often needs replacing too.
Buy the fix
Still stuck after the free fixes? These are the products we would look at.
| Pick | Product | Fixes | Who it's for | Buy |
|---|---|---|---|---|
| Best pick | Plastic toilet shims | a toilet that rocks on an uneven floor | Anyone whose bolts are snug but whose toilet still moves. | Check price |
| Budget pick | Toilet closet bolt set | stripped, rusted or snapped closet bolts | People whose old bolts are rusty or spin without tightening. | Check price |
| Upgrade pick | Toilet wax ring seal kit | a broken seal after the toilet has rocked for a long time | People who see water at the base, smell sewage, or have had a rocking toilet for months, and who can lift a heavy toilet with help. | Check price |
Plastic toilet shims
Fixes: a toilet that rocks on an uneven floor
Look for: Tapered wedges, so you can fine-tune the height; Waterproof plastic that does not rot or compress like wood or cardboard; A pack with enough pieces for every gap, usually 6 or more.
- Who it's for
- Anyone whose bolts are snug but whose toilet still moves.
- Honest downside
- The floor is soft or water is leaking at the base. Shims will not cure a damaged subfloor or a failed seal.
Toilet closet bolt set
Fixes: stripped, rusted or snapped closet bolts
Look for: Brass or stainless steel that will not rust; Washers, nuts and plastic caps included; Bolts that fit the slots of your flange.
- Who it's for
- People whose old bolts are rusty or spin without tightening.
- Honest downside
- Your bolts are fine. New bolts will not stop rocking on an uneven floor.
Toilet wax ring seal kit
Fixes: a broken seal after the toilet has rocked for a long time
Look for: A ring that matches your flange height, standard, extra thick or wax-free; Closet bolts and washers in the box.
- Who it's for
- People who see water at the base, smell sewage, or have had a rocking toilet for months, and who can lift a heavy toilet with help.
- Honest downside
- You cannot lift the toilet safely, the floor is soft or the flange is broken. Call a plumber.
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How we picked: How we picked: this page is based on toilet installation and repair guides, shim and wax ring maker instructions, and the problems and fixes people report in reviews. We do not test products by hand.
Check the bowl is level
Place a small level across the rim, then front to back. If the bubble is off, add or move shims until it sits in the middle. A tilted bowl can make the seat sit crooked and the flush behave oddly.
Signs the seal under the toilet has failed
- Water around the base, mostly after a flush
- A sewage smell that comes back after cleaning
- A stained, soft or lifting floor near the base
- A toilet that has rocked for months before you noticed
If you see any of these, stop shimming and plan to reset the toilet with a new seal.
What to skip
Wood or cardboard shims, and caulk as a shim
Cardboard and wood soak up water and squash flat, so the rock returns within weeks and they can rot. Caulk is not a support either. A bead of it in the gap leaves the bowl unsupported, so it still flexes every time someone sits down.
Frequently asked questions
Why is my toilet rocking?
Will a rocking toilet leak?
How tight should the closet bolts be?
Should I caulk around the toilet base?
Can I shim a toilet on a tile floor?
Related problems
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