It can quickly become confusing to understand paintbrush sizing, especially when each shape comes in a variety of sizes with numbering systems that are different between manufacturers. This journal article explains how the sizing systems work to help you make the right decisions when choosing the next brush for your project.
Brush sizes
Most paintbrush sizes are only given a number, which, unfortunately, is not standard across manufacturers. This number is always given on the handle and refers to the thickness, length, and width of the brush hair.
Sizes are also range-dependent. A size 4 round brush for watercolour will have a different handle length to a size 4 oil brush and a different hair length to a rigger brush. To help overcome these issues, product ranges have been listed with their sizes and respective hair lengths Link
Smaller brush sizes increase one at a time, but usually, from size 8 they go up in increments of 2. This is because in smaller brush shapes, a little change in hair length can make a huge difference, but the difference between a size 16 and 17 is only slight. This means that because certain hair types can be very expensive, size options were reduced.
The smaller the number, the smaller the brush size. In general, they run from:
20/0, 10/0, 5/0, 4/0 (sometimes 0000), 000, 00, 0, 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 16, 18, 20, 22, 24
Brushes smaller than zero are referred to as the number followed by nought. For example, 5/0 would be a size five nought.
The general rule of thumb to follow is:
- Small (20/0 – 5): Fine detail work, miniature painting, and lines.
- Medium (6 – 10): General painting, blending and moderate coverage.
- Large (12 – 14): Filling large areas and bold strokes.
- Extra Large (16 – 24): Large backgrounds and wide coverage.
Flat brushes are a little easier to understand. Although you’d still need to check the hair length, their sizes are provided as the measurement of their width. For example:
1/8”, 3/16”, 1/4”, 3/8”, 1/2″, 5/8”, 3/4″, 1”, 1.25”, 1.5”, 2”
Varnish brushes are similar, they are usually given as their width in mm. For example:
20mm, 30mm, 40mm, 50mm, 60mm, 80mm
Once you use a particular range of brushes enough, you’ll become familiar with the brush sizing and know what works best for you and your projects. Just make sure that you always check the sizing before buying brushes from a new manufacturer.
Johnny Thompson
As marketing lead, Johnny oversees blog editing, social media content and artist collaborations. His background includes paintbrush manufacturing and a degree in Business Management Practice from Leeds Beckett University
