Thinning Shears: Why 30 Teeth vs 40 Teeth Actually Matters (And Which You Need)

Thinning shears are among the most misunderstood tools in a stylist’s kit. The common assumption is that more teeth means less hair removed, but that oversimplifies what is actually happening. Tooth spacing, tooth width, tooth depth, and blade design all affect how much hair a thinning shear removes per cut. A 30 tooth shear from one manufacturer may remove more hair than a 40 tooth shear from another.

Understanding how these variables interact is the difference between controlled texturizing and accidental damage.

Cut Rate Percentages by Teeth Count

The “cut rate” is the approximate percentage of hair removed in a single closing of the shears. These ranges are based on manufacturer specifications and industry reference data. Actual results will vary based on technique, hair tension, and the specific shear design.

These numbers are starting points. The depth of your closing, the angle of the shear to the hair, and how many passes you make through a section all change the effective removal rate.

Blade Types

The shape of the teeth matters as much as how many there are. Three blade types are most common in professional thinning shears.

V-Groove Teeth

V-groove teeth have a notch cut into each tooth that grabs and holds the hair during cutting. This design provides maximum hair removal per cut and produces a more aggressive texture. V-groove thinning shears are best suited for thick, coarse hair where significant weight removal is the goal.

The tradeoff is visibility. V-groove cuts can leave more defined lines in the hair, which is desirable for some textured styles but problematic for smooth, blended finishes.

Flat Teeth

Flat teeth have a smooth, uniform surface. They produce a softer removal pattern and blend more naturally than V-groove designs. Most general purpose thinning shears in the 30 to 40 tooth range use flat teeth.

Flat tooth shears require more passes to achieve the same removal as V-groove, but they are more forgiving of technique errors. For stylists who work across multiple hair types, flat tooth thinning shears are the most versatile option.

Step Comb Teeth

Step comb designs (sometimes called “offset teeth”) use alternating short and long teeth. The short teeth guide the hair while the long teeth cut it. This produces a very soft, graduated removal pattern that is nearly invisible in the finished style.

Step comb thinning shears are the gentlest option and work well on fine or damaged hair where visible texture lines would be a problem. They remove less hair per pass than either V-groove or flat designs.

Matching Teeth Count to Hair Type

Fine Hair

Use 38 teeth or higher with flat or step comb blade designs. Anything with fewer teeth risks creating visible holes or stripes in the hair. Fine hair magnifies any unevenness in texture removal, so a conservative approach works best. Joewell, Kasho, and Hikari all make 40+ tooth models specifically designed for fine hair finishing.

Medium Hair

The most forgiving hair type for thinning work. Shears in the 30 to 40 tooth range with flat teeth cover most situations. You can adjust your removal rate through technique (angle, tension, number of passes) rather than needing multiple tools. This is where the broadest selection exists across every price point, from Mina and Jaguar at the accessible end to Mizutani and Juntetsu at the premium end.

Thick, Coarse Hair

Start with 20 to 30 teeth for bulk removal, then finish with 38+ teeth for blending. Trying to do all the thinning work with a high tooth count shear on thick hair takes too long and can lead to over-working the same sections. Kamisori, Ichiro, and Yasaka all offer aggressive chunkers in the 20 to 28 tooth range that handle coarse hair well.

Curly Hair

Curly hair amplifies texturizing mistakes. Use 40+ teeth with flat or step comb designs. Avoid low tooth count shears on curly hair entirely. A cut line that might be invisible on straight hair becomes a visible notch when the curl pattern tightens.

Technique Factors That Change the Cut Rate

The teeth count and blade type set the baseline, but your technique modifies the actual result.

Closing depth. A shallow close (not fully closing the blades) reduces the effective cut rate. A full, firm close maximizes removal. Controlling your grip pressure is one way to fine tune results without switching tools.

Angle to the hair. Cutting at a 45 degree angle to the hair shaft produces maximum removal. Cutting at 90 degrees (perpendicular) produces softer removal. Cutting parallel to the hair produces the gentlest blending effect.

Section size. Smaller sections give you more control over exactly where and how much hair is removed. Larger sections are faster but less precise. Match your section size to the tooth spacing of your shear for the most predictable results.

Number of passes. Multiple passes through the same section compound the removal rate. Two passes with a 15% shear does not remove exactly 30% of the hair (the second pass works on whats left, not the original volume), but it does increase overall removal significantly. Be cautious about repeated passes in the same area.

Common Thinning Mistakes

Using low tooth counts on fine hair. Shears with fewer than 30 teeth can create visible stripes or holes in fine hair. The wider tooth spacing removes chunks rather than blending, and fine hair does not have enough density to hide the pattern.

Over-thinning the crown. Removing too much weight from the top of the head causes the hair to stand up and lose its natural fall. The crown area should be thinned conservatively, if at all.

Wrong angle on damaged hair. Aggressive angles on already fragile hair accelerate breakage. Use perpendicular or parallel angles with high tooth count shears on compromised hair.

Relying on one thinning shear for everything. Different situations call for different tools. A single 35 tooth shear is a reasonable starting point, but stylists who work across diverse hair types benefit from having at least two thinning shears with different teeth counts.

Building a Thinning Shear Kit

Minimum kit (two shears):

1. One 30 to 35 tooth shear with flat teeth for general texturizing
2. One 40+ tooth shear for finishing and blending

Full kit (four shears):

1. One 20 to 25 tooth chunker for heavy bulk removal on thick hair
2. One 30 to 35 tooth shear for everyday texturizing
3. One 40 to 45 tooth finisher for blending and softening
4. One step comb design for fine or damaged hair work

Maintenance for Thinning Shears

Thinning shears need more attentive cleaning than cutting shears. Hair fragments get trapped between the teeth and, if left there, cause corrosion and dull the cutting edges.

After each client: Brush between the teeth with a soft bristle brush. Wipe the blades clean. Apply a drop of oil to the pivot.

Sharpening: Thinning shears require a sharpener who specializes in them. The teeth must stay aligned and uniformly spaced. A sharpener who simply grinds the flat blade without checking the toothed blade’s alignment can ruin the shear.

Storage: Always store thinning shears in a case or pouch. The teeth are more vulnerable to damage than a straight cutting blade, and even minor impacts can bend individual teeth out of alignment.

Sources

• Cut rate percentages based on manufacturer specifications and industry reference materials from Japanese and German thinning shear producers.
• Blade type descriptions based on standard manufacturing terminology used by Joewell, Mizutani, and other established thinning shear manufacturers.