Replacement Blades for Utility and Construction Knives
A dull blade tears. On drywall, film, tape or wallpaper - you see it immediately: ragged edge, skewed cut, fibres pulled loose.
The score lines on snap-off blades aren't decorative. Break a segment, get a fresh edge. Don't wait for the whole blade to go dull. On heavy drywall cutting that means a fresh segment every 10-15 passes.
What's here:
18mm blades - the site standard. Wider, stiffer, for drywall, OSB, thick card, mesh. Most construction knives take 18mm.
25mm blades - for heavy-duty knives cutting carpet, lino, dense insulation. Less common but worth having.
9mm precision blades - wallpaper, masking tape, thin films, detail finish work where a clean edge matters.
Trapezoidal blades (Stanley type A) - for fixed-blade knives, sheet metal, profiles, rigid materials.
Before ordering: check your knife handle for the blade width marking. A 18mm blade won't fit a 9mm knife body.
When it starts sliding instead of cutting, or when the cut edge looks torn rather than clean. On drywall that's roughly every 10-15 full passes at normal pace. Snapping a segment takes three seconds - faster than fixing a rough cut.
18mm is the standard for most site work: drywall, card, film, tape. 25mm is for heavy-duty knives cutting carpet, lino or thick insulation. Your knife handle will have the accepted blade width stamped or moulded on it.
Standard trapezoidal (type A, sometimes called Stanley type) fits the majority of European quick-change fixed-blade knives. Blade thickness can vary slightly between manufacturers though - check your knife's spec before buying in bulk.
They fit, but low-grade steel dulls 3-4 times faster. On a full site day you'll feel the difference by lunchtime. Carbide-steel blades cut cleaner and last longer - at any volume the cost per cut is lower.
Don't throw loose blades into a bin bag - they'll cut through it. Many snap-off knives have a storage compartment for used segments in the handle. Otherwise wrap in card before binning, or use a dedicated sharps container on larger sites.
