Why the blade matters
A utility knife is one of the most-used tools in a toolkit, and it appears on most lists of basic hand tools. The handle usually gets the attention, but the blade determines what the knife is good at. Different shapes are made for different materials, and using the wrong one tends to give poor cuts or put extra strain on your hand.
Handles and blades are not always interchangeable between brands. Check the packaging or your knife’s manual for the blade style it takes before you buy.
Common utility blade types
Standard trapezoid blades
This is the most familiar blade: a flat, trapezoid-shaped piece of steel with a pointed tip, usually with notches along the top so that it locks into the handle. It is the default blade in most utility knives and handles general jobs such as opening cartons, scoring drywall, trimming foam or cutting packaging. If you are only going to keep one type on hand, this is the usual choice.
Rounded-tip (box cutter) blades
These have a blunted or rounded point. They are intended for opening boxes and cutting packaging, where you want to cut the tape and cardboard without piercing what is inside. They reduce the risk of damaging contents, though the edge itself is still sharp.
Hook blades
A hook blade curves inward like a claw. The cutting edge is on the inside of the curve, so you pull it through the material. It is commonly used by flooring installers and roofers for materials such as carpet, linoleum, vinyl flooring and roofing shingles. The shape keeps the tip away from surfaces beneath and gives good control in thick material. Hook blades need a compatible handle.
Concave and rounded blades
Some blades have a curved cutting edge, often used for pulling or scoring cuts in flooring and plastic sheeting. Shapes vary by manufacturer, so look at the packaging description.
Serrated blades
Serrated blades have a toothed edge. They are generally used for tough, fibrous or soft materials that tend to slip under a plain edge, such as rope, some fabrics, and certain foam or insulation products. Serrated edges are harder to resharpen, and are usually simply replaced.
Snap-off (segmented) blades
These are long strips scored into segments. When the working tip dulls, you snap off the end with the supplied tool or a pair of pliers and expose a fresh tip. They are widely used for craft, light-duty cutting and paper, and they come in different widths. Snap-off blades are generally thinner than standard blades, so they may flex more on heavy materials. Take care when snapping, and dispose of the spent segments safely.
Scraper blades
Some utility knives accept wide scraper blades, used to remove paint, adhesive or film from smooth surfaces such as glass. They are meant for scraping, not cutting, and should be used with care on delicate surfaces.
Matching blades to jobs
| Job | Blade often used |
|---|---|
| General cutting, scoring drywall | Standard trapezoid |
| Opening boxes and cartons | Rounded-tip or standard |
| Carpet, vinyl, roofing | Hook |
| Rope, fabric, soft or fibrous materials | Serrated |
| Craft, paper, light-duty work | Snap-off |
| Removing paint or adhesive from glass | Scraper |
This table is a general guide. Always follow the instructions for your knife and the material you are cutting.
Blade materials and coatings
- Carbon steel. Common and economical, and holds a sharp edge but can rust if left damp.
- Bi-metal or alloy blades. Some blades combine a harder cutting edge with a more flexible body to resist snapping. Manufacturers use these for heavy-duty use.
- Coated blades. A coating can help reduce rust and drag in the cut.
- Ceramic blades. Some makers sell ceramic utility blades. They do not rust and can hold an edge for a long time, but they can chip if twisted or dropped, and they are not necessarily safer than metal blades.
The details vary by brand, so rely on the manufacturer’s description when comparing.
How to choose
- Think about what you cut most often.
- Check which blade type fits your knife.
- Buy a small pack of the blade type first, rather than a large variety.
- Keep spare blades in a safe, dry place.
Using and changing utility blades safely
- Cut away from your body and keep your free hand out of the path of the blade.
- Use a fresh blade when the old one drags or tears. Dull blades require more force and tend to slip, one of the reasons sharpening and edge condition matter.
- Retract or cover the blade when you are not using it.
- Unload and dispose of old blades in a sturdy container, such as a purpose-made blade bank or a thick plastic bottle with a lid.
- Part of every hand tool inspection should be checking that the blade locks securely in the handle and that the handle is not cracked.
Frequently asked questions
What are the different types of cutting blades?
For utility knives, the main ones are standard trapezoid, rounded-tip, hook, concave, serrated, snap-off and scraper blades.
Is a razor blade sharper than a knife?
A new single-edge razor blade can be very sharp, but it is thin and brittle. Utility blades are a little thicker and sturdier, so they are better suited to rougher work. Sharpness varies by product and condition, so there is no universal answer.
What is a “6” utility knife used for?
A number alone does not identify a tool, as sizes and model numbers differ between brands. Check the manufacturer’s description. Utility knives in general are used for cutting packaging, scoring materials and trimming.
Can I sharpen utility blades?
Most are designed to be replaced rather than sharpened.