If you've ever stood in front of the mirror holding a size 2 guard and wondering whether it's going to leave you looking sharp or shaved, you're not alone. Clipper guard numbers aren't standardised the way you'd expect, and the gap between a #1 and a #2 is bigger than it sounds. Here's what each size actually leaves behind, so you can pick the right one the first time.
Quick answer: a #1 guard leaves 3mm, a #2 leaves 6mm, a #3 about 10mm and a #4 about 13mm. Each full guard number adds 1/8 inch (roughly 3mm), so the number tells you how many eighths of an inch of hair you'll keep.
Clipper guard size chart in mm and inches
| Guard | Length (mm) | Length (inches) | What it leaves |
|---|---|---|---|
| #0 (no guard) | about 0.5mm* | – | Skin-close: a skin fade or fully shaved head |
| #0.5 | 1.5mm | 1/16 | Very close crop with a hint of stubble |
| #1 | 3mm | 1/8 | Classic buzz cut; common for the sides of a fade |
| #1.5 | 4.5mm | 3/16 | Softer buzz for a low-maintenance everyday cut |
| #2 | 6mm | 1/4 | Short with visible texture; a tapered crew cut |
| #3 | 10mm | 3/8 | Medium-short; styles with a bit of product |
| #4 | 13mm | 1/2 | A proper short haircut rather than a buzz |
| #5 | 16mm | 5/8 | Medium; a top length over a shorter fade |
| #6 | 19mm | 3/4 | Longer clipper work before scissor finishing |
| #7 | 22mm | 7/8 | Evening out length on longer styles |
| #8 | 25mm | 1 | Longest standard guard; blending longer lengths |
*With no guard fitted, the length depends on the blade and where the taper lever sits, so treat 0.5mm as a guide.
Millimetres to guard number
Know the length you want in mm? Here's the guard to reach for: 1.5mm is a #0.5, 3mm is a #1, 4.5mm is a #1.5, 6mm is a #2, 9–10mm is a #3, 12–13mm is a #4, 16mm is a #5, 19mm is a #6, 22mm is a #7 and 25mm is a #8. If the length you want falls between two guards, start with the longer one.
Why guard sizes matter more than you think
Every guard number corresponds to a specific length of hair left on the head, usually measured in eighths of an inch. The catch is that a size 3 doesn't feel like "medium" until you've used one — on some heads it looks close to bald on top, and on others it looks like it barely touched the hair. Knowing the exact millimetre measurement, not just the number, is what actually prevents a bad cut.
A few things the chart won't tell you
Hair texture changes how a guard looks once it's cut. Thick, coarse hair tends to look shorter than the number suggests because it stands up more; fine or thin hair lays flatter and can look almost a size shorter again. If you're between two sizes, it's almost always safer to start longer — you can always go back over with a shorter guard, but you can't put hair back on.
It's also worth knowing that guard sizing isn't universal across every brand. Most guards follow the numbering above, but always check the packaging or the brand's own chart before assuming a #2 from one brand matches a #2 from another — the difference is usually small, but it's there.
Fading: it's about more than one guard
A clean fade isn't one guard length, it's several blended together. A typical low fade might use a #1 at the very bottom, blending up into a #2 and #3 as you move up the sides, before landing on whatever length you're keeping on top. This is where clipper-over-comb technique and a steady hand matter as much as the guards themselves — but starting with the right set of guards makes the blending far more forgiving.
Working on facial hair? See our guide to fading a beard at home.
Keeping guards and blades in good shape
Guards clip onto the blade and can wear loose over time, which affects how evenly they cut. If yours are starting to slip or feel less snug than they used to, it's usually a sign they need replacing rather than the whole clipper. A drop of clipper blade oil after every few uses also keeps the blade itself cutting cleanly, rather than dragging or pulling — dragging is often mistaken for a "blunt guard" problem when it's really a blade maintenance issue. For the full routine, see how to maintain your hair clippers.
Whether you're maintaining a fade between barber visits or doing full home cuts for the family, having a proper guard set on hand — rather than guessing with just the two or three that came in the box — makes a noticeable difference in how consistent your cuts turn out. Choosing a new clipper? Compare options in our Wahl clipper buying guide or browse all hair clippers.
Clipper guard sizes: quick questions
How many mm is a number 1 guard?
A #1 guard leaves 3mm of hair, which is 1/8 inch.
What is a 1.5 guard in mm?
A #1.5 leaves about 4.5mm (3/16 inch), halfway between a #1 and a #2.
What is a 0.5 guard in mm?
A #0.5 leaves about 1.5mm (1/16 inch), just a touch longer than cutting with no guard.
How many mm is a number 3 guard?
A #3 leaves about 10mm (3/8 inch). One size up, a #4 leaves about 13mm (1/2 inch).
What guard number is 12mm?
In the standard numbered set, a #4 (13mm) is the closest to 12mm. A #3 (10mm) is the next size down.
Does a higher guard number leave more hair?
Yes. The higher the number, the longer the hair left behind: a #1 leaves 3mm, while a #8 leaves about 25mm.