Understanding hair trimmer sizes makes communicating with your barber easier and helps you cut your own hair at home. The numbers on clipper guards refer to the length of hair left after trimming—the lower the number, the shorter the cut. This guide breaks down the haircut number system so you can get the exact length and style you want every time.
The numbers in haircuts refer to the guard length attached to the clippers. Each number corresponds to a specific length of hair left on the scalp after trimming.
Hair clippers and trimmers follow a standard numbering system spanning from numbers 0 to 8. Clipper guards attach to the hair clipper, ensuring the blade cuts your hair to a certain length and not any shorter.
Key principle: Higher number guards will leave your hair longer, while lower number guards will leave you with shorter hair.
Most professional-grade clippers come with eight different guards, measured in eighths of an inch. Understanding the standard clipper guard numbering system helps you choose the right size for your desired style. Quality tools like the BS-808A professional clipper kit include a complete range of guards from #1 through #8.
Here are the standard guard numbers and sizes with their measurements:
| Guard Number | Inches | Millimeters | Hair Left |
|---|---|---|---|
| 0 or ½ | 1/16" | 1.5mm | Very minimal – shaved |
| 1 | 1/8" | 3mm | Very short |
| 1½ | 3/16" | 4.8mm | Still very short |
| 2 | 1/4" | 6mm | Short, less scalp showing |
| 3 | 3/8" | 10mm | Neat and clean |
| 4 | 1/2" | 13mm | Crew cut territory |
| 5 | 5/8" | 16mm | Taper-ready |
| 6 | 3/4" | 19mm | Styleable length |
| 7 | 7/8" | 22mm | Full crew cut |
| 8 | 1" | 25mm | Longest standard guard |
Clipper guards will dictate the length of your haircut. Your barber or stylist knows that these numbers correspond with different lengths, and depending on the hairstyle you ask for, they may use multiple guards during your haircut.
The way guard sizes look depends on hair thickness and texture. On some people, a number 2 is clear to the scalp; on others it's clean cut but you can't see skin.
General classification:
This is as short as you can go, outside of bald. A number 0 haircut means the clippers are used without any guard at all.
If you don't use a clipper guard and the lever on the clipper blade is closed, you will get the closest cut to your skin as possible. This is known as a zero-gap haircut because there's no space between the cutting blade and the fixed blade.
Ideal for: Skin fades, shaved heads, minimal upkeep
Heads-up: Your scalp will be fully exposed, so scalp care is key.
A short buzz cut with just enough hair to keep it interesting. The next clipper size up cuts to a length of 1/8 inches with the clipper guard closed.
Slightly longer than a 0, but still extremely short. This is a buzz-cut length, so the scalp is completely exposed. The barber typically goes between open and closed to help make the blending process seamless.
Haircut options: Buzz cut, fade, fade pompadour
Good for: Men with strong hairlines or bold styles, faded sides
This clipper size cuts to a length of 3/16 inches with a 1½ clipper guard closed. An open 1½ clipper guard is equivalent to a closed 2 clipper guard, leaving 1/4 inch of hair.
It's primarily cutting to buzz-cut length, still exposing the scalp. It's also used with a 1 and 2 for blending a fade.
Haircut options: Buzz cut, fade, textured crop
Style inspiration: Creates a textured crop hairstyle with extremely short sides while keeping longer, textured hair and fringe at the top.
A traditional buzz cut. Still short, but with a little more coverage. A number 2 guard leaves 1/4 inch of hair.
This clipper size cuts to a length of 1/4 inches—5/16 inches if it's open. A number 2 haircut may show less of the scalp, but if you have thin hair, you might want to go to a number 3 first. You can always have less hair taken off, but you can't put more hair on.
Haircut options: Buzz cut, fade, Caesar
Great for: Men with thinning hair—hides the scalp better than shorter guards. It's also one of the most common lengths used for fades and short crops.
Still a buzz cut, but on the longer side. The number 3 is one of the most requested all-over cuts.
This clipper size cuts to a length of 3/8 inches to about 7/16 inches if it's open. If you're opting for a fade, it might be best to ask your barber to start with a 3 so they can move down to a 2 and lower as they fade it out.
Haircut options: Buzz cut, fade, crew cut
Works well with: Thick or thin hair types. It's neat, smart and low-maintenance, making it a go-to for anyone who likes a short but not too short look.
You're officially in crew cut or brush cut territory. Heading into crew cut territory now, a number 4 haircut leaves 1/2 an inch of hair.
For a tapered look, start with a lower number guard toward the bottom and work up to a #4. This next clipper size cuts to a length of 1/2 inches when closed to 9/16 inches if it's open.
Haircut options: Buzz cut, crew cut, professional styles
Style tip: Pair it with a shorter fade on the sides for more dimension. It's also a popular choice for those transitioning from shorter styles to something longer.
Enough length to style it with some product. Want more to work with? The number 5 is a longer guard that starts to offer styling flexibility.
A number 5 cuts to a length of 5/8 inches when closed to 11/16 inches if it's open. It's tidy and polished but leaves enough length to use a comb or brush.
Haircut options: Taper
Barber's tip: Great for those who like shape without dramatic fades. It's ideal for tapered styles.
Just enough length to part the top or pull the bangs up a bit. At this length, we're moving firmly into "style it your way" territory.
A number 6 cuts to a length of 3/4 inches when closed to 13/16 inches if it's open. A number 6 cut offers enough hair to brush forward, part to the side, or slick back.
Haircut options: Taper, brushed styles, parted cuts
Perfect for: Maintaining volume while still keeping things tidy. It's also often used on the top of the head while shorter numbers are used on the sides for contrast.
You have the flexibility to pull off a variety of styles, including the side part, peaked cut, crew cut or Caesar cut.
This next clipper size cuts to a length of 7/8 inches when closed to 15/16 inches if it's open. The number 7 is often used for fuller crew cuts or textured styles that still lean on the shorter side.
Haircut options: Bushy crew cut, full-looking styles
Use with: Shorter guards on the sides for a modern look. It works especially well if you have thick hair and want to keep your length.
This is as long as it gets with a hair clipper. The highest number in the haircut number system cuts to a length of 1 inch when closed to 1 1/16 inches if it's open.
Consider this length for the top of the head while going shorter on the sides and back. This is typically the highest clipper guard number a barber can use before they switch to scissors or a different method to cut your hair.
Haircut options: Long buzz cut, longer short cuts, classic men's styles
Style tip: Works well when faded into shorter sides for contrast. Using a number 8 around your entire head keeps the style as simple and manageable as possible.
A barber's clippers can have a taper lever on them. The lever moves the cutting blade closer or farther away from the fixed blade, leaving your hair shorter or longer.
A closed taper is the default for the clipper guard lengths listed above. An open taper option keeps the fixed blade farther away from the cutting blade to leave your hair longer.
How it works:
When the barber moves the lever open or closed, it's a 1/16-inch difference in length. Closed will be a shorter cut, and open will be a longer cut.
Example: A closed clipper guard 1 will leave you with 1/8 inches of hair on your head. An open clipper guard 1 leaves you with 3/16 inches of hair on your head (1/8 or 2/16 + 1/16 = 3/16). While this might not seem like a huge difference, it does impact the hair blending and tapering process.
The barber can also move the lever in between closed and open while cutting your hair to taper it for a more gradual blend. Explore versatile hair cutting kits with multiple guards that include adjustable taper levers for maximum control at home.
Choosing the right guard depends on your hair type, desired style, and maintenance preferences.
For your hair type:
For your lifestyle:
Clippers are typically used for shorter haircuts. If you have medium-length hair or long hair, your barber might use scissors instead.
Maintenance needs:
Shorter cuts like a number 1 or 2 might need a tidy-up every 2-3 weeks. Regular trims every 3-4 weeks help keep your style sharp for most guard sizes.
Don't be afraid to ask your barber for recommendations—they'll factor in your head shape, hair type, and lifestyle to help you choose.
It's much easier to understand what clipper guard lengths look like by viewing actual haircuts.
Fade cut:
Brush cut:
Textured cut:
Side part:
Buzz cut:
Tousled cut:
Understanding proper skin care after clipping helps prevent irritation, especially with shorter guard sizes that expose more scalp.
Once you've got your ideal haircut length, maintaining it is key.
Trimming frequency:
Scalp care is especially important for shorter cuts where scalp is more exposed.
A number 3 haircut leaves 3/8 inch (10mm) of hair on your head when the guard is closed, or about 7/16 inches when open. It's one of the most popular all-over guard sizes because it's neat and low-maintenance while still providing decent coverage. The number 3 is also the longest guard typically used in a traditional fade as the top section.
Check the number stamped or printed on the guard attachment itself—most guards are clearly labeled with their number (1, 2, 3, etc.). If the markings have worn off, measure the length: each number equals that many eighths of an inch (so #2 = 2/8 or 1/4 inch, #4 = 4/8 or 1/2 inch). When in doubt, test on a less visible area first or start with a higher number and work down.
These numbers refer to the clipper guard size that determines how much hair is left after cutting. Number 1 leaves 1/8 inch, number 2 leaves 1/4 inch, number 3 leaves 3/8 inch, number 4 leaves 1/2 inch, and number 5 leaves 5/8 inch. Each number up adds another 1/8 inch of length. Lower numbers mean shorter hair with more scalp showing; higher numbers leave more hair for styling.
These measurements (0.8mm, 1.4mm, 2.0mm, etc.) are millimeter settings found on adjustable clippers, especially European or professional models. They represent the exact cutting length in millimeters rather than guard numbers. For reference: 1.5mm ≈ #0, 3mm ≈ #1, 6mm ≈ #2, 10mm ≈ #3. These precise measurements give barbers more control than standard numbered guards for detailed fading and blending.
A #10 blade cuts shorter than a #7 blade. In clipper blade numbering (different from guard numbers), higher blade numbers mean shorter cuts—the opposite of guards. A #10 blade leaves about 1/16 inch of hair, while a #7 blade leaves about 1/8 inch. Blade numbers refer to the blade itself, not the guards that attach to it, and are commonly used for pet grooming and professional barbering.
The 2.0 designation means 2.0 millimeters of cutting length. This is slightly shorter than a standard #1 guard (which is 3mm or 1/8 inch). Millimeter measurements are more precise than numbered guards and are common on adjustable European clippers or professional models. Some clippers use millimeter markings instead of numbers for exact length control during fades and detailed work.
Ready to master your haircut at home? Browse our complete selection at Bestbomg featuring professional clippers, guards, and grooming tools for every style from buzz cuts to textured fades.
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