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How to use a carpet knife

Updated: October 2026

You have a carpet knife, or one is on the way, and the next cut is either a lifted roll you want in sacks or a fitted carpet that still has to meet the skirting. How to use a carpet knife starts by keeping those two jobs apart. A disposal cut can happen on a board in the room you are clearing. Cutting in happens only after the carpet has been stretched. This page is the blade change, the hand, and the holster. It does not teach gripper, a knee kicker, or seams. Which knife to buy is on the [carpet knife comparison](/hub/cutting-tools/carpet-knife). Peter F. used the amazon.co.uk listings and public UK fitting notes, not a lab test.

You have a carpet knife, or one is on the way, and the next cut is either a lifted roll you want in sacks or a fitted carpet that still has to meet the skirting.

Our top picks

TradeUnderlay TradeUnderlay orange carpet fitter knife

Best overall

TradeUnderlay TradeUnderlay orange carpet fitter knife
8.0/10about £12.99
View offer
STANLEY Stanley FatMax heavy duty trade knife FMHT10501-0

Alternative

STANLEY Stanley FatMax heavy duty trade knife FMHT10501-0
5.0/10about £17.52
View offer
LuLuxinxin LuLuxinxin sprung-arm carpet cutter

Best value

LuLuxinxin LuLuxinxin sprung-arm carpet cutter
5.4/10about £4.99
View offer
On this page
  1. 1.Two different cuts
  2. 2.Changing the blade
  3. 3.Holster, hands, and old blades
  4. 4.When you stop

Two different cuts

A disposal cut is the lifted carpet, cut into pieces you can carry. Put a board under the line. Use a sharp blade, and keep your other hand behind the cut. Cutting in is the other job. Ulster Carpets says not to cut until the carpet is stretched, and to cut in with a straight or concave blade. A hook is a different profile, on hook blade for carpet. The knife does not replace a knee kicker or gripper. The single review of B0GMWP8B3Z is not a method. That reviewer had no carpet and tried cardboard.

Changing the blade

On the TradeUnderlay fitter knives the listing describes a thumb screw and a handle that opens for spares. Loosen the screw, seat the new blade fully, and tighten until it does not rock. A blade that shifts will tear the face yarn and can jump. The Stanley FatMax uses a coarse-thread thumb wheel and claims magnetic storage for 10 blades. That handle type is non-retractable, so the change does not give you a slider. The £4.99 cutters use a single screw. The LuLuxinxin listing asks about a safety lock and does not answer, so do not invent one. The other £4.99 review said notched blades did not match and that a blade with a hole seemed to be required. If the new blade will not sit flat, stop. The orange, green, and yellow include lines list a holster, not a packet of blades. Change the blade when the cut crushes the pile.
TradeUnderlay TradeUnderlay orange carpet fitter knife

Testsieger

TradeUnderlay TradeUnderlay orange carpet fitter knife
8.0/10about £12.99
View offer

Holster, hands, and old blades

A fixed blade needs a cover that covers it. HSE says to use a sheath if the knife travels, not to carry it in a pocket, and to match gloves to a cut standard. BS EN 388:2003 is about the glove, not a certificate for the knife. Put the knife in the holster and look at the bottom. One UK review of the orange knife said the fit was loose and the blade could protrude. If you can see the tip, do not wear it. The FatMax and both £4.99 cutters do not state a holster. Your other hand stays behind the blade. Old blades go in a sharps container. GOV.UK says you need a good reason to carry most knives in public. A belt holster while you are fitting can be that reason. It is not a licence to wear the knife to the shops.

When you stop

Call a fitter for stairs, patterned carpet, seams, and any room that needs a power stretcher, including Ulster’s note on runs over about 5 metres. A knife can cut the edge. It does not set the seam or the gripper. A one-room disposal cut, carpet lifted and a board underneath, is the job a careful householder can finish. Cutting in a carpet that still has to be stretched is the job to hand over if you have not done it before. A qualifying purchase through the comparison links can earn a commission at no extra cost to you.

Common questions

How do I cut a lifted carpet into pieces?
Work on a board if you can, with a sharp blade tight in the mount, and keep your other hand behind the cut. Section the carpet into pieces you can carry. That is a disposal cut, not a fit. A review that only tried cardboard is not proof a £4.99 cutter will do this on carpet. Change the blade if you start crushing the pile.
When do I cut during a fit?
After the carpet is stretched, not before. Ulster’s retailer guide says not to cut until it is stretched, and to cut in with a straight or concave blade. A hook is for a different edge. If the run needs a power stretcher, the knife is not the missing tool.
How do I change the blade on a thumb-wheel knife?
On the FatMax, use the coarse-thread thumb wheel the listing describes, seat the blade fully, and tighten until it cannot rock. On the TradeUnderlay knives the listing says a thumb screw and no extra tool. On the £4.99 cutters it is a single screw. If a notched blade will not sit, do not force it.
What do I do with old blades?
Put them in a sharps container. Do not drop them loose into the toolbox, a pocket, or a bag of offcuts. A used trapezoid or hook blade still cuts. HSE’s hand-knife guidance treats sharps disposal as part of the job, not an afterthought.
Is the holster enough?
Only if the tip stays inside it. Fit the knife, then check the bottom. The orange-knife reviews include a loose holster and a blade that can stick out if you push the knife in too far. Listings with no holster have not sold you that cover. HSE still says not to carry the knife in a pocket.
Can I walk to the van with the knife on my belt?
You need a good reason to carry most knives in public, which GOV.UK sets out. Moving a sheathed fitter’s knife as part of the job can be that reason. Wearing it for the rest of the day, off the tools, is not. Under-18s cannot be sold the knife in the first place.

Related pages

Best carpet knife

Carpet knife

Carpet knife buying guide: five checks before you pay

Hook blade for carpet: the profile, not the handle

Carpet knife vs utility knife: keep yours or add one

Sources

Public UK sources and amazon.co.uk listing lines; retrieved 19 October 2026.

  1. HSE, Hand knives (retrieved 19 October 2026)
  2. GOV.UK, Buying and carrying knives (retrieved 19 October 2026)
  3. Criminal Justice Act 1988 section 141A (retrieved 19 October 2026)
  4. Consumer Rights Act 2015 (retrieved 19 October 2026)
  5. Stanley Tools UK, FMHT10501-0 (retrieved 19 October 2026)
  6. Screwfix, Stanley FatMax FMHT10501-0 (retrieved 19 October 2026)
  7. Ulster Carpets retailer fitting guide (retrieved 19 October 2026)