Clipper Blade Numbers Explained: A Length Reference

Last updated: May 6, 2026

The Counterintuitive Rule Behind Blade Numbers

Clipper blade numbers explained in one sentence: the higher the number, the shorter the cut. This is the opposite of what most people guess on first glance, and it trips up new owners and even experienced groomers when they switch brands. A #10 blade leaves much less coat than a #4 blade, even though “ten” sounds bigger than “four.” The numbering refers to the gap between the cutting teeth, not to the length of hair the blade leaves behind.

Once you have the rule in your head, the rest of the system makes sense. Different numbered blades correspond to specific lengths in inches or millimeters, and groomers pick blades based on which body part they are clipping and how short the owner wants the finish.

This guide gives you a usable reference table, explains the difference between full-cut and skip-tooth blades, and walks through which blades belong on which body parts so you can communicate clearly with your groomer or pick the right blade for at-home work.

Quick Reference: Blade Number to Length

Length values below assume the standard Andis or Wahl A5-style blade system, which is what most professional groomers and serious home users own. Lengths are approximate because manufacturers vary slightly.

#3F (3/4 HT or “three full”): 1/2 inch (about 13 mm). The longest commonly used clipper blade. Leaves a fuller pet trim.

#4F: 3/8 inch (about 9.5 mm). Common pet body length, especially on doodles and longer pet trims.

#5F: 1/4 inch (about 6.3 mm). Standard pet body length on short trims.

#7F: 1/8 inch (about 3.2 mm). Short summer or sport clip body length.

#10: 1/16 inch (about 1.5 mm). Sanitary trims, paw pads, belly, inside of ears. The most-used blade in any groomer’s kit.

#15: 3/64 inch (about 1.2 mm). Slightly shorter than a #10. Often used for surgical preps and very short sanitary work.

#30: 1/50 inch (about 0.5 mm). Surgical-length. Used under guide combs, never against bare skin on a pet.

#40: 1/100 inch (about 0.25 mm). Surgical prep length. Almost never used directly on a pet coat.

Skip-Tooth vs Full-Cut Blades

The “F” suffix on a blade number stands for “full cut” or “fine,” and the difference matters more than most owners realize. A blade without an F (like #5 or #7) is a “skip-tooth” blade — it has alternating long and short teeth, leaves more coat behind, and creates a slightly choppier finish that fluffs up when brushed. A blade with an F (like #5F or #7F) has uniformly spaced fine teeth, cuts closer, and leaves a smoother surface.

Skip-tooth blades are often used on heavy double coats and on dogs whose coat is matted at the skin, because the wider teeth slide under tangles more easily. Full-cut blades give the smooth, even pet finish that most owners associate with a fresh groom.

If your groomer mentions using a #5 versus a #5F, they are choosing between a fluffier finish and a smoother one. Both leave roughly the same length of hair, but the texture is different. Most pet trims use full-cut blades for a tidier appearance.

Guide Combs (Snap-On Attachments)

Guide combs (also called attachment combs or snap-on combs) clip onto a short blade — usually a #30 or #40 — and add length back. They let one short blade do the work of many longer blades. A #30 with a 1-inch guide comb leaves about an inch of coat. A #30 with a 1/2-inch comb leaves a half inch.

Guide combs are popular for at-home grooming because the starter kit is smaller and cheaper. The trade-off is that the finish is less smooth than a true skip-tooth or full-cut blade in the same length, and the comb can drag if the coat is dirty, tangled, or wet. Always brush and bathe before clipping, then dry thoroughly. Our guide to bathing a dog at home covers the prep step.

Guide combs also flex with the body contour, which can leave longer and shorter patches on curved areas. This is fine for a casual home trim and noticeable on a show finish.

Which Blade for Which Body Part

Most pet grooms use just three or four blades total, applied to different zones of the body.

Body and back: #4F, #5F, or #7F depending on desired length. Most pet trims land at #5F (1/4 inch) or #7F (1/8 inch).

Legs and chest furnishings: Often left longer than the body. Many groomers leave the legs scissored rather than clipped, or use a longer attachment comb over a #30 blade to blend.

Belly and sanitary area: #10 blade, used carefully and at slight angle to skin. Read more in our sanitary trim guide.

Paw pads and between toes: #10 or #15 blade with the corner. See our paw pad trimming guide for technique.

Face and head: Usually scissored on most pet breeds. Clipped flat on Schnauzers, Poodles, and a few other specific breed cuts using #10 or #15.

Inside the ear (where allowed): #10 or #15. Avoid clipping inside the ear canal itself; only the outer ear leather.

Blade Heat and Coat Damage

Clipper blades get hot during use. A blade that has been running for a few minutes can burn skin or cause clipper rash on sensitive areas like the belly and groin. Pro groomers swap blades during long grooms or use a cooling spray (Andis Cool Care, Oster Spray Lube) every few minutes to keep blade temperature down.

Always check blade temperature against your inner wrist before pressing it back to the dog’s skin. If it feels warm to you, it is too hot for the dog. Switch to a cool spare or pause for a few minutes. This matters most with short blades (#10, #15, #30) and on thin-skinned dogs.

A dull blade is also a problem. Dull blades pull hair instead of cutting cleanly, which hurts the dog and creates streaky lines in the coat. If you are running a blade through a section three or four times to get a clean cut, the blade needs sharpening or replacement.

Wahl, Andis, Oster, and Cross-Brand Compatibility

The good news is that the major professional clipper brands (Andis AG and AGC, Oster A5, Wahl KM series) all use the same blade-attachment standard, so blades are largely interchangeable across brands. A blade marked #10 from Andis fits an Oster A5 and gives essentially the same length.

The naming and numbering conventions are nearly identical too, with minor exceptions for specialty blades. If you are switching brands, your existing blade collection still works.

Cordless clippers from the same brands often use a slightly different blade attachment, so check before buying. And budget home clippers (the kind that come in a thirty-dollar starter kit) usually have proprietary blades or guide combs that are not cross-compatible with pro blades.

How Often to Replace Blades

A well-maintained professional clipper blade lasts hundreds of grooms before needing professional sharpening. The signs that a blade needs service: it pulls hair instead of cutting, it leaves streaky lines, it heats up faster than usual, or you can see chipped or worn teeth.

Sharpening services are inexpensive (often ten to fifteen dollars per blade) and most groomers send blades out two or three times a year. If you clip your own dog at home and are seeing dull blade symptoms, sharpening costs about the same as a new budget blade and lasts much longer.

Cleaning matters more than sharpening for most home users. After every groom, brush hair off the blade with a small brush, drop a few drops of clipper oil between the teeth, and wipe down. A blade that is kept clean and oiled stays sharp far longer than one that gets put away dusty.

Common Mistakes With Blade Selection

Three blade-related mistakes show up over and over in DIY grooming.

Using too short a blade on a body coat. A #10 (1/16 inch) on a dog’s body leaves a near-shaved finish that exposes the skin to sun, abrasion, and clipper rash. Save short blades for sanitary, paws, and belly only. Use a #5F or #7F for body work.

Going against the grain. Most pet trims clip with the direction of hair growth. Going against the grain produces a much shorter cut at the same blade number, which can result in a noticeably uneven finish if you switch directions mid-groom.

Clipping a dirty or wet coat. Clippers were designed for clean, dry coats. Clipping a dirty coat dulls the blade fast and produces a streaky finish. Clipping a wet coat tears hair and damages the blade. Always bathe, dry, and brush first.

Adopted Dogs and Coat Surprises

If you have adopted a dog whose coat history is unknown, the first home or pro groom is partly diagnostic. Your groomer may need to start with a longer blade than you expect just to get through the coat without snagging on hidden mats. Once the coat is clean and reset, future grooms can move to your preferred length.

For coat care advice across breed types, our dog care blog covers brushing, bathing, and clip schedules for the most common adopted breeds. You can also browse adoptable dogs at our adopt a dog hub.

Frequently Asked Questions

Why is a higher blade number a shorter cut?

The number reflects the spacing between the cutting teeth: tighter spacing equals a shorter cut. A #10 blade has tighter teeth than a #4, so it leaves less hair behind. The system was set decades ago and never changed for clarity, so you just have to memorize it.

What blade leaves the dog’s body about a quarter inch?

A #5F blade leaves approximately 1/4 inch (6 mm). This is one of the most popular pet body lengths because it looks tidy without being so short that the dog gets cold or sun-exposed.

Can I use guide combs instead of buying multiple blades?

Yes, guide combs are the budget-friendly approach for home grooming. They snap onto a short blade (typically #30) and add length. The finish is slightly less smooth than a dedicated blade in the same length but adequate for most pet trims.

Why does the same blade leave different lengths on different dogs?

Coat density, hair direction, and how taut the skin is held all affect the final length. A blade also cuts shorter on a dog whose hair has been wetted and stretched (do not clip wet) and on areas where you go against the grain.

How do I keep my blades sharp longer?

Always clip clean, dry, brushed coats. Brush the blade between sessions, oil the teeth with clipper oil after every use, and store in a dry place. Send blades for professional sharpening when they start to pull hair or leave streaks.

Are home clipper kits as good as professional brands?

Generally no. Budget kits use weaker motors, lower-quality blades, and proprietary attachments that limit your options. If you plan to clip your own dog regularly, an entry-level Andis or Wahl professional clipper is worth the upgrade.