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Snap-off or trapezoid utility blade

Updated: October 2026

You can buy either blade this afternoon, and only one of them will lock in the knife you already own. A snap-off or trapezoid utility blade is a choice of system, knife included, not a choice of brand colour. The two are not substitutes. The [utility knife blades comparison](/hub/diy-supplies/utility-knife-blades) shows both families in one table. This page says when to buy which, including 18 mm against 25 mm in one short section. Peter F. used the amazon.co.uk listings on 16 October 2026, plus Stanley's and OLFA's width notes. There was no lab test. A qualifying purchase can earn us a commission at no extra cost to you.

You can buy either blade this afternoon, and only one of them will lock in the knife you already own. A snap-off or trapezoid utility blade is a choice of system, knife included, not a choice of brand colour.

Our top picks

Bosch Professional Bosch Professional 1600A01V3J

Best overall

Bosch Professional Bosch Professional 1600A01V3J
7.7/10about £15.55
View offer
OX OX Pro 25 mm, OX-P220710

Preis-Tipp

OX OX Pro 25 mm, OX-P220710
5.5/10about £8.57
View offer
OX OX Pro 18 mm, OX-P220510

Alternative

OX OX Pro 18 mm, OX-P220510
4.6/10about £5.39
View offer
On this page
  1. 1.They are different knives
  2. 2.When a trapezoid blade is the one to buy
  3. 3.When a snap-off blade is the one to buy
  4. 4.18 mm or 25 mm
  5. 5.The recommendation

They are different knives

A trapezoid blade is short and stiff. It sits in a retractable utility knife, the pattern people mean by a Stanley 1992 knife. A snap-off blade is a scored strip in a long body. The slots do not overlap. An 18 mm strip will not replace a trapezoid, and a trapezoid will not feed an 18 mm snap-off knife. Stanley's InterLock 0-10-018 is an 18 mm metal snap knife with eight segments.

When a trapezoid blade is the one to buy

Buy a trapezoid when you want a short stiff edge for cardboard, plastic strapping, and general sheet, and the knife in the drawer is already that shape. In this set, Bosch 1600A01V3J at £15.55 is 50 trapezoid blades in a dispenser that stores used blades. If the sheet is thick and the snap-off blade is extended a long way, the trapezoid is the more predictable of the two. Carpet is neither: a hook is a different profile, and the utility knife blades buying guide keeps the wider checklist.
Bosch Professional Bosch Professional 1600A01V3J

Testsieger

Bosch Professional Bosch Professional 1600A01V3J
7.7/10about £15.55
View offer

When a snap-off blade is the one to buy

Buy snap-off when the knife is already a snap-off knife and you dull tips quickly on tape, card, and paper. A fresh segment is the point of the system. OLFA treats 18 mm as the common width and 25 mm as the extra-heavy-duty width. Sollex's snap-off guide says you leave about 10 mm proud and snap one segment at a time. The method, pliers rather than fingers, is on how to change a utility knife blade. A snap-off blade extended too far is a lever. It is the wrong tool when you need the short stiffness of a trapezoid in thick material.

18 mm or 25 mm

If you have chosen snap-off, match the width already in the knife. OX-P220510 at £5.39 is a 10-pack titled 18 mm SK5 with 8 segments and a dispenser. Two bullets also say 25 mm, so check the first blade and do not trust both sentences. OX-P220710 at £8.57 is a 10-pack whose title and fit bullet agree on 25 mm, with 7 segments. That agreement is why it is the best value for someone who already owns a 25 mm knife. A 25 mm blade will not lock in an 18 mm body. You do not put the 25 mm strip in the InterLock.

The recommendation

If the knife is a retractable trapezoid, buy trapezoid blades: Bosch at £15.55 when you want 50 and a used-blade slot, or the Stanley listing at £10.86 only after you count. If the knife is 18 mm snap-off, buy the 18 mm OX pack and treat the 25 mm sentences as a clash. If the knife is 25 mm, buy OX-P220710. Do not buy both families for one knife. Who should skip the trapezoid top pick, including carpet work, is on best utility knife blades.

Common questions

Can I use snap-off blades in a Stanley 1992 knife?
No. The 1992 pattern is a trapezoid with two tips, 62 mm by 0.63 mm on Stanley's UK page. A snap-off strip needs a snap-off knife of the same width. Forcing an 18 mm blade into a retractable Stanley knife will not give you a safe lock. Buy the matching family.
When is a trapezoid the better buy?
When you want a short stiff edge and you already own that knife, or you are about to buy one for card, strapping, and general sheet. In this set that means Bosch at £15.55 for a known 50, or the Stanley listing after you count the pack. It is the weaker choice for carpet pile.
When is snap-off the better buy?
When the knife is a snap-off knife and you dull edges quickly on tape and card. You get a new segment instead of turning one trapezoid tip. Keep the extension short, about 10 mm proud on Sollex's guidance, and snap with pliers. It is a poor bargain if the body you own is trapezoid.
Should I get 18 mm or 25 mm?
Match the knife. 18 mm is the common width, and Stanley's InterLock is an 18 mm example with eight segments. 25 mm is the heavier strip and will not lock in an 18 mm body. Here the consistent pack is OX-P220710 at £8.57. The £5.39 pack is titled 18 mm and also says 25 mm.
Are OX's 114 reviews a reason to prefer snap-off?
No. Both OX listings show 4.6 from 114, and the texts describe snap-off knives rather than a blade-only test. Prefer snap-off when the knife and the job match, not because of that shared star line. The trapezoid review files, Bosch and Stanley, are the ones that talk about blades.
What about carpet?
Carpet wants a hook, not a longer snap-off extension and not a straight trapezoid as a substitute. One Stanley review in this set said carpet tiles dulled a trapezoid quickly. Use the carpet and vinyl page for hook and concave packs. This versus page stops at the two main systems.

Related pages

Trapezoid blades comparison

Utility knife blades

Best utility knife blades: count, fit, and reviews

Utility knife blades buying guide: match the knife

Utility knife blades for carpet and vinyl flooring

How to change a utility knife blade safely at home

Sources

GOV.UK, legislation.gov.uk, the Crown Prosecution Service, HSE, Stanley UK, OLFA UK, Westminster and a JIS note on SK85 (SK5). Prices and stars are the amazon.co.uk listings for the nine ASINs in this comparison. Prices move.

  1. GOV.UK, buying and carrying knives (retrieved 17 October 2026)
  2. Criminal Justice Act 1988, section 139 (retrieved 17 October 2026)
  3. CPS, knife and other weapons offences (retrieved 17 October 2026)
  4. HSE PPS12, knives in the workplace (retrieved 17 October 2026)
  5. Stanley UK, 1992 utility blade (retrieved 17 October 2026)
  6. OLFA UK, how to snap off cutter blades (retrieved 17 October 2026)
  7. Westminster, knives and rubbish sacks (retrieved 17 October 2026)
  8. JIS G 4401 note, SK85 (SK5) (retrieved 17 October 2026)