The #10 and #30 are the workhorses of professional dog grooming. You’ll find both on every groomer’s blade shelf — but they do almost opposite jobs, and swapping them is a common mistake that costs dogs comfort and groomers time.
The quick specs
| Blade | Leaves | Official use | Risk level |
|---|---|---|---|
| #10 | 1.5–1.6 mm (1/16”) | Sanitary prep, face/feet, legal comb base | Safe |
| #30 | 0.5 mm (1/50”) | Comb base only, never body alone | Hot/close |
The #30 is nearly three times shorter than the #10. That tiny difference means everything.
#10: The sanitary-prep standard
The #10 blade is on the “all breeds” sanitary prep rule on both the Andis and Oster official charts. This means:
- Every professional clipper ships with a #10 (or starts with one in your kit). It’s the default “I don’t know what blade to use, so I’ll grab the #10” blade.
- Face, feet, and tail base, especially on double-coated breeds where you’re working around sensitive skin. Poodle face is the textbook example — a #10 keeps the corners of the eyes and ears safe while still cutting close enough for a clean profile.
- It can legally live under a snap-on metal comb, per all three major brands. Andis explicitly lists the Universal comb as compatible with #10; Wahl says #10 is permissible; Oster’s charts show #10 under combs in puppy-trim recipes. You can use it as a comb base if you want colder work and more control.
The #10 is the safe choice. At 1.5–1.6 mm, it cuts close enough for sanitary work but far enough from skin that a little tremor won’t cause a burn.
#30: The comb base
The #30 is a different animal. It exists for one reason: to sit under a snap-on metal comb and provide a uniform, tight base so the comb teeth do the real cutting.
The official guidance is universal: Oster’s breed recipes are literally written as “30 & 1” UC” (meaning #30 blade, 1-inch Universal Comb). Andis and Wahl both list #30 as the best-practice base. The word “best” matters — they allow #10 and #15 as alternatives, but #30 is what the charts recommend.
Why? Because the #30 leaves only 0.5 mm, so every comb tooth sits flush and cuts uniformly. The gap between the blade and comb is minimal, which means:
- No striping — the coat falls at exactly the comb’s length all the way down.
- Less blade friction — a #30 touching skin directly would be hot, but riding under a comb acts like a safety spacer, and the comb itself does the actual cutting.
- Longer blade life — the comb glides over hair, not teeth dragging through mats.
The heat trap: #30 on bare skin
Here’s where most rookie mistakes happen: someone thinks “the chart says use #30, so I’ll use #30” and runs it directly on the dog’s body without a comb.
Do not do this. Wahl’s official safety guidance for close-cut work reads: “If you decide to use this setting, please be cautious to avoid any cuts or nicks to your pet’s skin.” The #30 is 0.5 mm — essentially skin-short. A clipper running that close heats up fast, and even a light hand tremor can cause razor burn or a small nick.
The #30 was designed to run under a comb. The comb is the safety device. Without it, you’re flying blind.
If you absolutely must use a #30 without a comb (say, a belly pad or sanitary trim where a comb doesn’t fit), take frequent breaks, oil the blade every 20–30 seconds, and touch the clipper body to check heat. The moment it feels warm, stop.
The Wahl 5-in-1 trap: Same number, different blade
This one catches experienced groomers. If you own a Wahl 5-in-1 adjustable clipper (Bravura, Arco, Chromado, Creativa, Figura), your #30 setting does not equal an A5 #30 blade.
Wahl’s 5-in-1 #30 setting leaves 0.8–1.3 mm, according to their own help pages — which is nearly double the A5 #30’s 0.5 mm. You could learn “put a #30 under a comb on your A5 Oster” and then pick up a Bravura and think you’re following the same rule, but the same number gives you a totally different cut.
This is why Wahl officially groups these systems separately — their A5-compatible blades are one product line, their 5-in-1 blades are another, and the numbers don’t translate between them. Before you swap blades or combs, always check the clipper system first.
Which to keep in your kit
- #10: The all-purpose close blade. Sanitary prep, face and paw work, and emergency comb base if you’re out of #30s.
- #30: The comb foundation. Keeps comb work striping-free and blade heat low. Never alone on skin.
The real answer: carry both. A #10 is your safety net for detailed close work and sanitary trim. A #30 (or two, since they wear faster) is your comb base — and once you’ve run a #30 under a 1-inch comb, you’ll never go back to using a #10 for that job.
Heat and break strategy
Both blades run hotter than longer-cut sizes — they’re cutting closer, which means finer teeth and higher friction. For both:
- Oil the blade every 20–30 seconds of continuous work.
- Feel the clipper body. If it’s warm, stop. Let it cool while you move to another dog or task.
- On the #30 especially, work in short passes. Don’t let the blade idle on skin.
- If the blade gets hot enough that you can’t hold it comfortably, it’s hot enough to burn. That’s your sign to stop.
The blade-comb-finder can help you lock in the right setup for your clipper — just enter your model, and it’ll tell you what blades and combs your system accepts, so you never have to second-guess the blade numbers again.
For the full mapping of blade numbers to cut lengths across brands, see the clipper blade numbers guide and the #30 detailed page.