Paintbrush Size Chart & Cross-Brand Reality Check
A general guide to what brush size numbers mean, plus real measured data showing why the same size number is not the same physical brush from one brand to the next.
What Does My Brush Size Number Mean?
Real Measured Example: A "Size 8 Round" Is Not One Fixed Size
Independent measurements of actual size 8 round brushes from several well-known brands show just how much brush numbering varies:
| Brand & Range | Measured Width |
|---|---|
| Escoda Óptimo | 4.40 mm |
| da Vinci Series 36 | 4.7 mm |
| Princeton Umbria | 4.73 mm |
| Princeton Velvetouch | 4.9 mm |
| Rosemary & Co Series 33 | 5.2 mm |
| Rosemary & Co Ivory (synthetic) | 9.0 mm |
That is roughly a 2× difference in actual width, all labelled "size 8". A similar spread shows up at size 10: Princeton's Neptune size 10 measures 5.81 mm wide, while Princeton's own Velvetouch size 10 measures 5.6 mm.
There Is No Universal Brush Size Standard
This is not a case of one brand doing it "correctly" — major manufacturers openly acknowledge the inconsistency. Princeton states that "brush sizes vary by manufacturer and may be labeled based on the width of the hair." Rosemary & Co puts it plainly: "there is no universal brush size." da Vinci notes that "the European brush industry has never managed to agree on common standards."
It can even run backwards within a single range: da Vinci's Series 673 rigger is numbered so that size 0 measures about 6.5 mm, while size 6 measures only about 2.9 mm — the opposite of what you would expect.
How to Use This Guide
Select a general size range from the dropdown to see what that range is typically used for. Below that, you will find real, independently measured data comparing how differently the same size number is made across brush brands.
Why Brush Numbers Are Confusing
Unlike a standardised unit such as millimetres, a brush "size number" is simply a label each manufacturer chooses for its own product line. There is no shared industry standard tying a number to an exact width, which is why a size 8 round from one brand can be noticeably larger or smaller than a size 8 from another.
What To Do About It
When buying a specific brush size for detailed work, check the brand's own published measurements (ferrule width or hair width) rather than assuming the number alone tells you the physical size, especially if you are substituting a brush from a different brand for one specified in a tutorial or pattern.
Common Brush Shapes
Alongside size numbers, brush shape also affects what a brush is good for: round brushes offer more precision and control, flat brushes cover more area but sacrifice tip precision, filbert brushes offer a rounded edge with reasonable precision, and angular, fan, liner and mop brushes each suit more specialised techniques.
Frequently Asked Questions
Do all brands use the same brush size numbers?
No. Brush size numbers are not standardised across the industry. The same number, such as "size 8", can refer to noticeably different physical widths depending on the brand and even the specific range within that brand.
How different can a "size 8" really be between brands?
Independent measurements found a size 8 round ranging from about 4.40 mm (Escoda Óptimo) to 9.0 mm (Rosemary & Co Ivory synthetic) — roughly double, for the same labelled size.
Do brush manufacturers acknowledge this inconsistency?
Yes. Princeton, Rosemary & Co and da Vinci have all publicly stated that brush sizing is not standardised across the industry.
Can a brand's own sizing even run backwards?
In at least one documented case (da Vinci's Series 673 rigger), yes — size 0 measures larger than size 6 within that same product line.
What should I do when a tutorial calls for a specific brush size?
Where precision matters, check the actual measured width (in mm) from the brand's own chart, rather than assuming the number alone will match a different brand's brush of the same number.
What is the difference between a round and a flat brush?
Round brushes come to a point and offer more precision and control for detail, while flat brushes have a squared edge that covers more area per stroke but with less tip precision.
Is bigger always better for basecoating?
Not necessarily. Larger brushes cover area faster but with less control near edges, so many painters use a mid-to-large size for open areas and a smaller brush for edges and details.
Is this guide free to use?
Yes, this guide is completely free to use with no sign-up required.
Related Colour Tools
Ready to Create with Colour?
Explore beginner-friendly Creative Flair by Sana painting kits with carefully selected colours and approachable step-by-step guidance.
Explore Painting KitsBrush size figures and brand comparisons shown here are drawn from independently published measurements and manufacturer statements, provided for general educational reference. Always check the specific brand's own published size chart before buying if exact dimensions matter.