Reference · Updated August 2026

Paint Brush Size Chart

Measured hair width and length by size and shape, taken from manufacturers' own published spec tables. This page exists because the number on the handle is not a measurement, and every chart that pretends otherwise is guessing.

By the Austin Gallery editors · August 8, 2026

Update, 8 August 2026. The da Vinci ladders in this page were added after first publication. The first version of this page carried no da Vinci figures at all, on the mistaken basis that da Vinci did not publish them. It does, per size, on individual product pages. That claim has been removed and corrected. A later research pass collected 343 published rows across 30 da Vinci series, and they are reproduced below with their provenance stated.

A number 8 round, across brands

The single most useful table on this page. Every figure is published by the manufacturer named in the row. Nothing here is interpolated, converted from a different size, or estimated.

Princeton Velvetouch Series 3950, 5-Piece Set (Round 8, Filbert 8, Round 2, Spotter 5/0, Angle Shader 1/4 in)

about $51 on Amazon

Every brush in this set appears by name in the Velvetouch table above, so you can read the exact published width and hair length of each one before you buy. That is unusual, and it is the reason Velvetouch is the series this page leans on hardest.

The makers say it themselves

It would be easy to assume this is an oversight nobody admits to. It is not. Five manufacturers state it on their own sites:

• Princeton: brush sizes vary by manufacturer and may be labeled based on the width of the hair, such as a quarter inch angle, or a general size, such as a number 6 round.
• Winsor & Newton: each number does not necessarily equate to the same size brush in different ranges, and this is particularly noticeable between English, French and Japanese sizes.
• Rosemary & Co: there is no universal brush size; their brush sizes are different to every other brush company, and are not comparable across their own ranges either.
• Pro Arte: most paintbrush sizes are only given a number, which, unfortunately, is not standard across manufacturers.
• da Vinci: "Unfortunately the European brush industry has never managed to agree on common standards for brush types and sizes." They add the commercial consequence in the next breath: "The differing numeration often leads to miscalculations when prices are compared."

Pro Arte's catalogue supplies the hard numbers behind its own claim. Across its ranges, a brush sold as a size 8 round carries anywhere from 22 mm of hair (Prolene Series 101, Acrylix Series 202, Masterstroke Series 60) to 32 mm (Sterling Acrylix Series 201, and the hog round). The same effect appears at the small end: a Pro Arte size 0 is 8 mm of hair as a Prolene round, 13 mm as a Prolene signwriter and 20 mm as a Prolene rigger. One brand, one number, three brushes.

The most telling evidence is that one manufacturer manages to argue both sides. da Vinci's printed catalogue states that da Vinci complies with international standards on brush type sizes, and in the same breath advises never buying a brush size blindly and always comparing the diameter. da Vinci's own website says something else entirely, in the sentence quoted above. The website also carries the concrete admission: "English producers use numbers for brush sizes that differ from those in Germany. With water colour brushes the difference up to size 6 is one complete number, e.g. the English size 2 corresponds to our size 3." That rather settles the question, and further down this page we put a number on it using da Vinci's own published dimensions.

For fairness, da Vinci does record a direction of travel: "During the last years all markets have converged. The effect has been a first standardization of synthetic brush assortments and sizes, which is now also followed by Asian brush producers." A first standardization of synthetic assortments is not the same claim as a standard, and their own numbers, below, do not yet show one.

We could not locate a current, in-force standard for artists' brush sizes from ISO, ASTM or BSI. We are reporting that as a failure to find one rather than as proof that none exists.

Even the inch labels are not literal

Flats, washes and mops are often labelled in inches rather than by number, which sounds like it should settle the matter. It does not. One inch is 25.4 mm. Here is what Princeton publishes for brushes it labels one inch, all within its own catalogue:

Princeton Neptune Series 4750, 4-Piece Synthetic Squirrel Set (Aquarelle 3/4 in, Oval Wash 1/2 in, Rounds 4 and 12)

about $39 on Amazon

A useful demonstration of the wash problem in one box: the Aquarelle and the Oval Wash carry inch labels, and Princeton publishes very different hair lengths for them at the same nominal width.

The same number means different things by shape

This is the part most size charts skip entirely. Within one brand and one series, the size number tracks a different dimension depending on the shape. Princeton's published figures at size 8 make it plain:

Escoda's catalogue makes the same point in a different way. Its master chart publishes one shared width scale that several shapes reuse, so at any given size the filbert and the bright are exactly the same width, and only the hair length distinguishes them. All fourteen width values are identical across the two rows. At size 8:

Note the vocabulary too. Princeton calls the short flat a Chisel Blender in Velvetouch and a Bright in Umbria. Rosemary & Co calls it a Short Flat in most of its ranges. Escoda groups bright and flat together. If you are matching a brush you already own, matching the shape name is no safer than matching the number.

Round brush size ladders

Read as width mm / hair length mm. Blank cells mean the manufacturer does not offer that size in that series, not that we could not find it.

Escoda publishes the same ladder a different way, with one diameter series shared by all four of its watercolour ranges and the hair length varying by range. Óptimo and Reserva are the kolinsky lines; Perla and Versàtil are synthetic, and run slightly shorter.

Rosemary & Co publishes width and length in millimetres for every size in every series. Its Series 33 pure kolinsky pointed round runs from 10/0 at 0.8 mm wide with 6.4 mm of hair, through size 8 at 5.2 by 24.2 mm, up to size 16 at 10.7 by 41.5 mm. Sizes 18 and 20 appear in the table with no figures published.

Escoda Versàtil Travel Set, 3 Round Pointed Brushes, Sizes 2, 6, 10

about $84 on Amazon

Escoda is one of the few makers that publishes a diameter and a length for every size in every series, which is what lets this page compare its ladder against Princeton's directly.

da Vinci publishes every size, and no table anywhere

da Vinci does publish dimensions on its own site, and publishes them thoroughly: a diameter, a visible hair length and a total length, for individual brush sizes, one product page at a time. Their own wording is "On our website you will find details of all our brush series, like the diameter, visible hair length and total length." What does not exist anywhere on their site is a consolidated size table. There is no per-series chart and no downloadable dimension sheet, so the only way to compare a size 4 against a size 8, or one series against another, is to open two product pages and hold the numbers in your head.

That absence is exactly the gap this page fills. We read 343 published rows across 30 da Vinci series from their own per-size article pages and reassembled them into the ladders below. Everything in this section is da Vinci's own figure. Nothing is interpolated, averaged, converted from a different size, or taken from a retailer.

da Vinci round ladders

Series 35 is the useful one, because it is the da Vinci round that publishes both fields across the whole range, from 3/0 up to 24. It is the MAESTRO kolinsky in the extra long, extra pointed body.

Three more da Vinci rounds publish both fields. Read as diameter mm / hair length mm. Series 36 is red sable, 5580 is the COSMOTOP-SPIN synthetic and 5598 is CASANEO. Blank cells mean the size is not offered in that series.

Series 10 against Series 11: the English body, measured

Series 10 and Series 11 are both MAESTRO kolinsky rounds. For neither of them does da Vinci publish a diameter at all, at any size, so the diameter column below does not exist. That is a genuine gap in their data, not a gap in ours. What they do publish for both is visible hair length at every size, and that is enough to do something no other manufacturer on this page lets you do.

Series 11 is da Vinci's explicit "English" body line: the same hair, in the fuller shape the English trade uses. Series 10 is the German body. So placing them side by side turns the English-versus-German numbering gap from an anecdote into a measured, in-house quantity.

Pair that with da Vinci's own published sentence: "English producers use numbers for brush sizes that differ from those in Germany. With water colour brushes the difference up to size 6 is one complete number, e.g. the English size 2 corresponds to our size 3." Their numbers agree with their prose. Series 10 size 3 is 14.0 mm of hair, and Series 11, the English body, reaches 14.0 mm at size 2. One complete number of offset, published by the maker, in millimetres.

Series 673: the numbering runs backwards

Every other maker on this page numbers upward. If you take one thing from this page, take this: the number on the handle is an index into a catalogue, and a catalogue can index in whichever direction its maker chose. It is not a measurement, and it is not even reliably an ordering.

Size 10 inside one factory: 16 mm to 31 mm

The cross-brand table at the top of this page shows a number 8 varying about twofold between manufacturers. That comparison is easy to wave away as different companies doing different things. This one is not. Every row below is a brush stamped 10, made by da Vinci, sold by da Vinci, with the hair length da Vinci publishes for it.

Same maker, same fibre, different numbers: Series 1570 against 1670

Series 1570 and Series 1670 are both da Vinci NOVA synthetics. 1670 is the long-handle version. They are, as far as da Vinci's own published dimensions can tell you, the same brushes on different sticks, and they are numbered differently. Read as diameter mm / hair length mm.

Series 5080: when the size number is the width, until it is not

The section above on inch labels showed that a brush sold as one inch is usually not 25.4 mm. da Vinci's Series 5080 mottler is the mirror image of that problem, and briefly the most honest numbering on this page: the size number simply is the width in millimetres. A size 40 is 40 mm across. That holds exactly up to size 80. Above it, the published width drifts below the number.

Two more clean da Vinci comparisons

Series 70 against Series 76. Both are MINIATURE MAESTRO rounds. da Vinci publishes identical diameters for them at every size and different hair lengths, which isolates a single variable more cleanly than anything else we found in any maker's data.

Series 364 flat against Series 365 filbert. Same range, same numbers, and on the flat the size number is close to the width in millimetres. The filbert at the same number is markedly narrower, which is the shape difference the page's Princeton section describes, here in one maker's own figures. Read as width mm / hair length mm, remembering that on these shapes da Vinci's diameter field carries the head width.

Flat, filbert and bright ladders

Again width mm / hair length mm, from Princeton's published tables. The Velvetouch columns show the clean version of the bright-versus-flat difference: identical size numbers, similar widths, and hair lengths that separate them.

Wash, mop and quill

Liner, rigger and script

What each shape is actually for

Descriptions below are quoted or closely paraphrased from the source named in the last column, rather than written from general knowledge.

da Vinci Casaneo Series 5598 Round Brush Set, Sizes 0, 1, 2, 3, 4

about $43 on Amazon

The exact series in the da Vinci ladder above, and the one carrying the two published inversions we flag: da Vinci lists size 1 at 1.2 mm diameter against 1.7 mm for size 0, and size 4 at 2.5 mm against 2.6 mm for size 3. Buying the range rather than a single number sidesteps that entirely, which is a reasonable way to shop a ladder you cannot trust to run in order.

How to read a size number

Sizes run upward through whole numbers, and downward through a fractional notation. Pro Arte explains the small end directly: brushes smaller than zero are referred to as the number followed by nought, so 5/0 is a size five nought, and the larger the top number, the smaller the brush. Princeton's Velvetouch range runs down to 18/0, published at 0.53 mm wide with 5 mm of hair for the round and 0.56 mm wide with 3 mm of hair for the spotter.

Princeton also publishes the only plain use-based rule we found from a manufacturer: brushes below size 4 are usually for detail work, sizes 4 to 6 are for small areas, and sizes above 6 are for broad spaces. Treat that as a rough map, then check the millimetres.

Anomalies we are publishing rather than quietly fixing

Five figures across Princeton's and da Vinci's own tables run against the direction of their own ladders. We checked the Princeton ones in both the inch and the millimetre blocks, so none of them is a unit-conversion artifact, and we re-fetched the da Vinci ones to rule out a transcription error on our side. They are reproduced above as published, and flagged here:

• Umbria 6250 Filbert: size 8 is published at 14.3 mm wide, size 10 at 12.5 mm. The larger number is the narrower brush. Hair length still increases, 28.5 mm to 34 mm.
• SNAP! 9650 Round: size 3/0 is published at 2.24 mm wide, size 2 at 2.06 mm. The same inversion appears in the 9850 line, where 2/0 and 0 are both 2.08 mm against size 2 at 2.06 mm.
• SNAP! Round 20: published at 16.5 mm in the 9850 line and 11.1 mm in the 9650 line, even though every other shared size in the two ranges matches exactly.
• da Vinci Series 5598 CASANEO, size 1: published at 1.2 mm diameter, against 1.7 mm for size 0. The size above zero is narrower than zero. Hair length still increases normally, 7.5 mm to 8.5 mm, so this is not a whole row shifted out of place.
• da Vinci Series 5598 CASANEO, size 4: published at 2.5 mm diameter, against 2.6 mm for size 3. Again the hair length behaves, 12.0 mm to 14.0 mm. Both 5598 inversions survived a repeat fetch.

Series 673, in contrast, is not on this list. Its whole ladder descends, so it is not an anomaly inside an otherwise ascending table; it is a series that is numbered the other way round. We have treated it as a finding rather than an error, and it has its own section above.

We also excluded one set of figures entirely. Princeton's Velvetouch "Petals" shape publishes zeros for width and length at sizes 6, 8 and 10 in both unit blocks. Those are placeholders, not measurements, so they are not in the tables above.

Related references

This is one of three technical references we keep for painters. The lightfastness ratings reference translates between the ASTM, Blue Wool and manufacturer permanence systems, and the paper weight conversion chart gives lb to gsm by paper type. For what goes on the brush, see our watercolor set guide and oil paint set guide; for gift shopping, our gifts for painters guide.

Frequently asked questions

Sources

Dimensions are attributed to the manufacturer that published them. Princeton's figures come from the Dimensions blocks on its series pages, which publish inches and millimetres side by side under the column headers Size, Length and Width.

• Princeton Artist Brush Co series pages: Neptune 4750, Velvetouch 3950, Aqua Elite 4850, Umbria 6250, SNAP! 9650 and SNAP! 9850
• Princeton, Brush Anatomy (the sizing paragraph and the size-to-use rule) and Princeton, Brush Shapes
• Escoda product pages for Óptimo 1210, Reserva 1212, Perla 1430 and Versàtil 1540
• Rosemary & Co, Series 33 pure kolinsky pointed rounds, Ivory pointed rounds, Ivory short flats, Ivory long flats, and the note that there is no universal brush size
• Pro Arte, How does paint brush sizing work and Pro Arte Prolene 101 round
• Winsor & Newton, on paintbrush shape and size for watercolour
• da Vinci dimensions: every da Vinci figure on this page was read from da Vinci's own per-size article pages at davinci-defet.com, in the form /de/artikel/VA-<series>_<size>, each of which carries a server-rendered measurements block giving diameter of the brush body, visible hair length and total length. 343 rows across 30 series. There is no consolidated size table, no per-series chart and no dimension PDF on their site; the on-page size tab renders the same per-article data one size at a time.
• da Vinci statements: Explanation of technical terms and symbols, which publishes "Unfortunately the European brush industry has never managed to agree on common standards for brush types and sizes", "The differing numeration often leads to miscalculations when prices are compared", "On our website you will find details of all our brush series, like the diameter, visible hair length and total length", "English producers use numbers for brush sizes that differ from those in Germany. With water colour brushes the difference up to size 6 is one complete number, e.g. the English size 2 corresponds to our size 3" and "During the last years all markets have converged. The effect has been a first standardization of synthetic brush assortments and sizes, which is now also followed by Asian brush producers." The German original of the first reads "Leider hat sich die europaeische Pinselindustrie bis jetzt noch nicht zu einer allgemein gueltigen Standardisierung der verschiedenen Pinselarten und -groessen zusammenfinden koennen." Set against this, da Vinci's printed brush catalogue, page 33, claims compliance with international standards on brush type sizes and advises always comparing the diameter. We cite the catalogue without a deep link because the two statements do not appear on the same page.
• Escoda catalogue, the full-scale shape chart on printed pages 8 and 9, which publishes diameter, width, thickness and length in millimetres per size
• Shape definitions: Blick's brush shape guide and Blick on how a brush is measured, both retailer technical guides rather than manufacturer specifications