Dog Clipper Blades Explained: Which Number to Use

There’s one fact that turns a dog clipper blades guide from baffling to obvious: on a clipper blade, the higher the number, the shorter the cut. A #10 leaves more hair than a #30, and a #4 leaves more than a #10. Get that backwards – and plenty of first-time owners clipping a cavoodle do – and you can take a coat to the skin when you only meant to tidy it.

The numbers feel arbitrary until you see the pattern, and then the whole wall of blades at the grooming shop starts to make sense. Here’s what each number actually leaves, the letters that trip people up and which blade to reach for on which part of the dog.

On dog clipper blades, a higher number means a shorter cut – a #10 leaves about 1.5mm, a #4F about 9.5mm. ‘Finish’ blades (the F) give a smooth result, while skip-tooth blades take more off and leave it rougher. Clip-on guide combs work the opposite way, where a higher number leaves more hair. Reach for a #10 on paws and sanitary areas, a #5F or #4F for an easy body trim.

The one rule that trips everyone up

With detachable clipper blades, the number tells you how close the teeth sit to the skin, not how much hair you keep. So the count runs backwards from what feels right. A #3 or #4 leaves a longer coat, a #10 takes it down to a neat 1.5mm and a #40 is the surgical-close blade a vet uses, not a haircut length. Once that clicks, the chart below reads in seconds.

Dog clipper blade size chart

These are the standard ‘finish’ blade lengths we reach for most, and they’re the same across the big brands – a #10 is a #10 whether it’s Wahl, Andis or Oster. Lengths are approximate and vary a touch with coat type and how hard you press.

Blade	Leaves roughly	Best used for
#3F	13mm (1/2″)	Longest clip length – fuller summer body trims you’ll scissor to finish
#4F	9.5mm (3/8″)	Medium ‘teddy bear’ body length on curly and wool coats
#5F	6.3mm (1/4″)	Short, easy-care pet body clip – the popular low-maintenance length
#7F	3.2mm (1/8″)	Very short body work and clearing light knots
#10	1.5mm	The all-rounder – sanitary, belly, paw pads, ears, light tidy
#15	1.2mm	Closer work where you want it a little tighter than a #10
#30	0.5mm	Base blade under snap-on combs and very close finish work
#40	0.25mm	Surgical-close only – not a body length, leave this to the vet

Skip-tooth blades carry the same numbers without the F (a #5, #7 and so on). They leave the same length but with wider-spaced teeth, so they cut faster through bulk – and rougher. Use them to take weight off, then tidy with a finish blade.

Finish, skip-tooth and what the letters mean

The letter after the number is the bit no one explains. ‘F’ stands for finish, sometimes called full-tooth – the teeth are close together, so the cut comes out smooth and even. ‘FC’ means finish cut and does much the same job. A skip-tooth blade has alternating long and short teeth that chew through thick or slightly matted coat quickly, but it leaves a coarser surface you wouldn’t want as a final look. T-blades are wider for big bodies. For almost all home grooming on a Labrador or a family pet, finish blades are the ones you want.

The other numbers: clip-on and snap-on combs

Here’s where it gets genuinely confusing. The plastic clip-on combs that come with cheaper home clippers use the opposite logic – a higher number leaves more hair. A #1 comb might leave around 3mm, while a #8 leaves about 25mm (an inch). They clip over a single fixed blade and are fine for a rough all-over trim.

Then there are metal snap-on combs, the ones groomers use over a #30 or #10 blade to dial in a longer length without swapping blades. These are usually labelled by the length they leave rather than a confusing number, so a ‘half inch’ comb leaves about 13mm. If the numbering on your set has you second-guessing, a clear comb length chart for your brand is worth keeping on the shelf.

Which blade for which job

For faces, ears, paws, the belly and a sanitary trim, a #10 does most of the work – it’s close enough to be neat but long enough to be forgiving on soft skin. Step up to a #15 only when you want it a touch tighter. For a clean, low-fuss body clip on a pet, a #5F at about 6mm is the length most owners are happiest with, and a #7F if you want it shorter again.

Want length left on? A #4F or #3F keeps a fuller, scissored ‘teddy bear’ look. Poodle and doodle feet and faces are the exception – groomers often go very short there with a #15 or #30 for that clean poodle finish, which takes practice to get right.

Wire-coated breeds like the miniature schnauzer are usually clipped with a #10 on the body if you’re not hand-stripping, with longer combs left on the legs and beard. And the big caveat: don’t take a short blade to a double coat. A Samoyed or husky should be deshedded, not clipped down, because a close blade wrecks the coat and removes its sun and heat protection.

Hot blades, clipper burn and blade care

Blades get hot fast, and the shorter ones like the #30 and #40 heat quickest, especially on a long grooming run. A hot blade on thin skin – the sanitary area is the classic spot – causes clipper burn, a red, irritated patch that shows up a few hours later. Stop and touch the blade to the inside of your wrist every minute or so; if it’s too hot for you, it’s too hot for the dog. Blade coolant spray or a quick swap to a second blade fixes it.

Care matters more than people think, too. A dull or gummed-up blade pulls hair, runs hotter and gives a ragged cut, so brush, oil and wipe blades after each use and have them sharpened when they start to drag. Sound clipping technique – steady pressure, going with the coat, a calm dog – does as much for the finish as the blade itself.

Common mistakes

The errors that come up again and again:

• Assuming a higher number leaves more hair. With blades it’s the opposite – that’s how coats end up shaved by accident.
• Using a skip-tooth blade for the final pass and wondering why the coat looks tracky and uneven.
• Running a #30 or #40 over the body. That’s a surgical length, not a summer cut.
• Ignoring blade heat until the dog flinches, then finding a burn on the belly the next day.
• Trying to clip a matted or double coat down with a short blade instead of deshedding or seeing a groomer.

Buying in Australia and when to call a groomer

Wahl, Andis and Oster are the names you’ll see at Petbarn, PETstock, Pet Circle and Amazon AU, and the detachable A5 blade system they share is universal – a #10 fits across the brands, so you can build a blade set over time. Budget single-blade home clippers rely on those clip-on combs instead, which is fine for a tidy-up but limited for detailed work.

If you’re shaping a poodle face, clearing a heavy mat or clipping a nervous dog, that’s the point to book a pro rather than push through it. Looking for a groomer accredited through the Pet Industry Association of Australia is a reasonable sign they’ve trained on blades and coat types, not just bought a clipper kit.

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