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Shampoo Dilutions

Blade and Comb Lengths

This article is going to cover an extremely common series of questions gets asked all the time.

  • Does the length of the blade shown on the blade itself LEAVE that much hair or take that much hair off?
  • Are the measurements on the blades listed accurate when used in reverse or with the lay of the hair?
  • Do the blades and combs leave the same amount on every coat?
  • Why do I get different lengths of hair using blades and combs on the same dog?

To some of us this all sounds really easy and simple, but honestly, it can be a bit complicated!

Let’s start with the first question.

Blades LEAVE the amount of hair (roughly) that they say they do, they do NOT take that amount off. Think about it for a minute. The blade sits on the skin and the cutter is the measurement it says AWAY from the base of the blade. That is where it cuts:


See how its sitting flat on the counter? the cutter is the part that moves and the distance from the table to the cutter is how much hair it will leave. Combs are the same way. They LEAVE hair roughly the length of comb, they do not take that much OFF.

Make sense? I hope so! Now onto the next question.


This is a 4f blade and notice it leaves 1/4 inch according to the ruler. That equals just over 6mm which is the length listed on the back of my Oster 4f.

The lengths listed on combs and blades are what they leave when used in reverse on most coats however.


The reason for the measurements being taken in reverse and being more accurate than with the lay is simple when you think about it.

The teeth of the comb and blade are technically referred to as a COMB. Because the comb picks the hair UP and lifts it to the cutter it provides a more uniform and smooth finish. When you go against the lay it tends to push hair down. This is particularly true if drop coated dogs like Shih-Tzu and Yorkie are being groomed with a longer blade because the weight of the clipper blade and clipper cause the hair to lay down resulting the hair being longer. At times, like when you are doing a larger dog (Tibetan Terriers and Bearded Collies come to mind) and want to leave more hair, this can be extremely advantageous. At other times (when doing a Shih-Tzu or double-coated dogs like Labrador Retrievers) it can be problematic and result in a shaggy groom that is much longer than the owner wanted, and adding much frustration as well as grooming time to the person grooming the dog.


The dog in the above photo is a Tibetan Terrier that weighs about 45 pounds. He was done using the Oster XL 2 inch snap-on comb WITH the lay of the hair. The result was about 4 inches of hair after being done. If it had been done in reverse it would have been a much more in line with the measurement on the comb itself.


Notice the length on this is showing 1 inch of hair. The dog had been groomed with the Wahl #1 Stainless Steel for a 5 in 1 clipper. That comb lists a length of 12mm which is the equivalent of approximately 1/2 an inch. That is a big difference! Roughly double the listed length when used with the lay of the hair.

AND if that is not confusing enough, the fact that there are different types of coat as well throw even more variables into the mix.

For example. A thicker coated drop coat will leave more a different length than a thin coated one will and a plush coated dog with undercoat will leave a different length than all the others. A poodle, well, you guessed it! A different length again!



Remember the 4f blade above? This is the results of that blade being used on a semi-drop coated dog with the lay of the hair it left roughly 1/2 of an inch.


Blades and combs do NOT Leave the same length on every part of the  coat either. Some parts (thinner or coats that swirl backwards in places) will have different lengths and that is not a bad thing on drop coats. It allows you to have a more natural look to the coat. Layers of different lengths allow for fill and a softness that cannot be achieved if the hair is all the same length (like in backbrushing too much).

Hopefully you know a bit more about how measurements and blades/combs work now.