40mm vs 60mm Round Brush: Sizes for Volume and Blow-Drying
By Kent Brushes | The World's Finest Hairbrushes & Combs | Published: 2026-11-01
Category: How-to Guides
Learn how to choose between a 40mm and 60mm round brush for volume, and follow a step-by-step blow-dry routine that uses each size correctly.
Quick answer
Choose a 40mm round brush for short hair, fringe, and precise root lift; choose a 60mm round brush for medium to long hair when you want curl, volume, and a smoother blow-dry. Use the smaller brush for the roots and the larger one for the lengths and ends.
Why diameter changes the blow-dry result
Barrel diameter controls two things: how much tension you can apply and how much bend the hair takes. A 40mm barrel is narrow enough to reach the scalp and lift roots without over-directing the hair, while a 60mm barrel covers more surface area and creates a rounder, softer curl. If you use a large brush on short hair, the barrel cannot get close enough to the root to lift it; if you use a small brush on long hair, you will need more passes and may struggle to smooth the lengths evenly.
Match the brush to your hair length and goal
For hair that ends above the jaw or for a fringe, a 40mm brush gives you control and prevents the brush from overwhelming the section. For hair that reaches the shoulders or longer, a 60mm brush is more efficient for creating volume and a slight curl at the ends. If you have very long or thick hair, you can still use a 40mm brush for the root area and switch to the 60mm for the mid-lengths and ends. The trade-off is that two brushes require a little more coordination, but the result is more targeted volume.
Bristle type and barrel material matter too
Bristle mix affects shine and grip. Natural bristle (like boar) creates tension and smoothness, while nylon adds grip and helps detangle. Ball-tipped nylon quills are gentle on the scalp and work well for lifting roots without scratching. A brush with a mix of bristle and nylon can promote shine while distributing natural oils, as seen in the Perfect For Volumising 60mm Bristle Nylon Mix Round Brush - PF03. However, if you have very fine hair, a pure bristle brush may be too soft to create lasting volume; a nylon mix gives more grip. Always check the brush's care instructions, as some materials should not be used with certain styling products.
Step-by-step blow-dry routine for volume with 40mm and 60mm brushes
- Start with roughly 80% dry hair: Towel-dry until hair is damp, not dripping. Apply a heat protectant and rough-dry until the hair is about 80% dry. Common mistake: starting on soaking wet hair, which prevents the brush from gripping and can cause heat damage before the hair is ready.
- Section the hair: Divide hair into sections no wider than the brush barrel. For a 40mm brush, use smaller sections (about 2-3 cm); for a 60mm brush, sections can be slightly larger. Clip the rest of the hair out of the way. Checkpoint: if a section is wider than the brush, the hair will not wrap evenly and volume will be uneven.
- Lift roots with the 40mm brush: Take a section at the crown or front hairline, place the 40mm brush under the hair at the root, and roll it upward toward the scalp while directing the dryer nozzle at the root. Hold for a few seconds, then release. Common mistake: pulling the brush straight out instead of rolling, which reduces lift.
- Switch to the 60mm brush for lengths and ends: For medium to long hair, use the 60mm brush on the mid-lengths and ends. Place the brush under the section, roll it downward or upward depending on the desired curl, and follow with the dryer. Keep the dryer moving to avoid overheating. Checkpoint: if the hair starts to tangle, you are rolling too much hair at once—reduce the section size.
- Set with cool air: After each section is dry, press the cool shot button for a few seconds while the hair is still on the brush. This sets the shape and adds shine. Common mistake: skipping the cool shot, which leaves hair limp and prone to frizz.
- Finish with a light hold spray: Once all sections are dry, mist a flexible-hold hairspray over the roots and lengths to lock in volume. Avoid heavy sprays that weigh hair down. Checkpoint: if you used a lot of product, brush through gently with a clean 40mm brush to remove excess.
Products mentioned in this guide
- Kent Create 40mm Ball-Tipped Nylon Quill Round Brush - KCR6: 40mm ball-tipped nylon-quill round brush ideal for all hair types, short in length, creating root lift and volume. The ball tips gently glide through knots, so you can lift roots without scratching the scalp, making it a good choice for short hair and fringes.
Kent Create 40mm Ball-Tipped Nylon Quill Round Brush - KCR6 - Perfect For Volumising 60mm Bristle Nylon Mix Round Brush - PF03: 60mm bristle and nylon mix round brush ideal for curling and adding volume to medium to long hair. The larger barrel creates a rounder curl and the bristle-nylon mix promotes shine while distributing natural oils, which helps prevent split ends during blow-drying.
Perfect For Volumising 60mm Bristle Nylon Mix Round Brush - PF03
