How to choose utility knife blades: width, thickness and type

The right replacement blade has the same width and the same type as your utility knife: 9, 18 or 25 mm, snap-off or trapezoidal. Check these two details on the utility knife before ordering, because a blade of the wrong size will not fit or will rattle in the slide. Then choose the thickness: in the collection you will find blades from about 0.4 to 1 mm, thinner ones for precise cuts in soft materials, thicker ones for heavy-duty use.

The types

• Snap-off blades: segmented blades with break lines. When the cutting edge goes dull you snap off the segment and have a fresh edge. Like the Stanley 25 mm snap-off blade.
• Trapezoidal blades: blades without segments, replaced as a whole when they no longer cut.
• Blade sets and blades in dispensers: multi-piece packs, also in dispensers, like the 9 mm blades in a dispenser and the 18 mm blades.
• Replacement blades for specific models: designed for one particular utility knife, for example the Portwest KN90 blades for KN10 and KN20 utility knives, in packs of 10.

How to choose by job

The features to look at

• Width: 9, 18 or 25 mm for snap-off blades. This is the dimension that has to match the utility knife.
• Thickness: in the collection 0.43, 0.5, 0.55, 0.7 mm and more (up to 1 mm for especially sturdy blades). The thicker it is, the longer it lasts on heavy cuts; the thinner, the cleaner it cuts soft material.
• Dimensions: for example 80 × 9 × 0.6 mm or 100 × 18 × 0.7 mm (length × width × thickness). They are needed to compare blades of different brands.
• Quantity per pack: from single blades to sets of 10 and more. It is worth buying quantities in line with your use, because a worn blade is less safe.

Common mistakes

• Taking the wrong width: the blade must be the same width as the utility knife.
• Persisting with a worn blade: it makes you press harder and the cut slips. Snap off the segment or change the blade.
• Changing the blade without gloves: cuts to the fingers happen precisely during replacement.
• Throwing used blades away loose: they go in a closed container.
• Snapping off the segment with your fingers: use the dedicated tool or the cap of the utility knife.

Frequently asked questions

How do I know which blade my utility knife needs?

Measure the width of the current blade, 9, 18 or 25 mm, and check whether it is snap-off or trapezoidal. If the utility knife has a model code, look for the blades listed for that model.

Can I fit a blade from another brand?

Often yes, if width and type match. If in doubt, choose the blade specified for your utility knife.

When should the blade be changed?

When it stops cutting cleanly and you have to push. With snap-off blades it is enough to snap off the dull segment, as long as there are any left.

Are thin or thick blades better?

Thin for clean cuts in soft materials, thick for hard cuts and heavy-duty use.

The blades are in the Utility Knife Consumables collection: to find the right one for your utility knife, request a quote or ask the AMES technicians for advice.