Short answer
The Posca PC-5M has a 1.8 to 2.5 mm reversible medium bullet tip and is the all-rounder for rocks, wood, canvas and paper. For detail, step down to the PC-3M (0.9 to 1.3 mm) or the PC-1M and PC-1MR (0.7 mm). For bold work, step up to the PC-7M (4.5 to 5.5 mm), PC-8K (8 mm chisel) or PC-17K (15 mm). A PC-5M plus a 0.7 mm pen covers most projects.
The Posca PC-5M
Posca describes the PC-5M as a 1.8 to 2.5 mm medium bullet tip whose versatile tip offers unlimited freedom of use. The tip is reversible, so when one end wears or picks up color you can flip it, and Posca sells replacement tips coded PCR5. The page lists the paint as water-based, mixable and layerable, quick drying, with strong UV resistance, and made in Japan; it describes nearly 40 shades, including fluorescents and metallics (Posca PC-5M page).
- Fills and lines from one pen: broad enough to fill a palm-size rock or a letter, narrow enough to outline.
- The widest color range of any Posca size on Amazon, sold singly, in 3 counts of one color and in sets of 8, 16, 24 and 48.
- Limits: too thick for eyes, small lettering and dot work; too slow for backgrounds bigger than a hand.
Every Posca size compared
Posca marker sizes by model
| Model | Tip | Width | Best for |
|---|---|---|---|
| PC-1MR | Calibrated extra fine, ringed in metal | 0.7 mm | Technical lines, tiny lettering, contours |
| PC-1M | Extra fine bullet | 0.7 mm | Details, dots, eyes, small text |
| PC-3M | Fine bullet, reversible | 0.9 to 1.3 mm | Writing, outlines, medium dots |
| PC-5M | Medium bullet, reversible | 1.8 to 2.5 mm | All-round: fills and lines |
| PC-5BR | Semi-flexible brush | About 1 to 4 mm, per the listing | Lettering, strokes that swell and taper |
| PC-7M | Broad bullet | 4.5 to 5.5 mm | Bold lines, posters, big rocks |
| PC-8K | Broad chisel | 8 mm | Headlines, fills, calligraphy strokes |
| PC-17K | Rectangular extra broad | 15 mm | Backgrounds, murals, big letters |
Widths are from Posca’s product pages and Amazon listing titles. Posca’s range page also lists a very fine PC-1MC, a soft brush PCF-350 and an extra large round PCM-22 (Posca range). Compare these widths with other brands on the tip size chart.
Posca markers fine tip: PC-1M, PC-1MR or PC-3M?
All three are for detail, but they feel different:
- PC-1MR has a calibrated extra fine tip ringed in metal; Posca recommends it for roughs, technical drawings and adding details and contours with precision (Posca PC-1MR page). It keeps a sharp, even line, best on smooth paper.
- PC-1M is also 0.7 mm but a soft bullet, more forgiving on rough surfaces such as rocks and wood. It is the one rock painters use for eyes and dots.
- PC-3M at 0.9 to 1.3 mm is the writing size, with more coverage per stroke than the 0.7 mm pens and a reversible tip.
For other brands’ fine tips, see fine tip paint markers.
Thick Posca markers: PC-7M, PC-8K and PC-17K
The PC-7M is a fat bullet for bold lines that still feels like a pen. The PC-8K is an 8 mm chisel: hold it flat for broad strokes, on its edge for thin ones. The PC-17K is a 15 mm rectangular block for backgrounds and murals. Wide Poscas hold a lot of paint and need more shaking and priming. Other brands’ wide markers are on thick paint markers.
Which Posca sizes to buy for a project
Posca sizes by project
| Project | Main size | Add |
|---|---|---|
| Rock painting | PC-5M | PC-1M for eyes and dots; white PC-3M |
| Black paper art | PC-3M and PC-5M | PC-1MR for line work |
| Sneakers and fabric | PC-3M | PC-1M for outlines |
| Canvas painting | PC-5M | PC-8K or PC-17K for backgrounds |
| Lettering | PC-5BR brush | PC-3M for small text |
| Posters and murals | PC-8K | PC-17K for fills |
Sets that bundle sizes are compared on Posca marker sets, and every white is on white Posca markers.
Posca size care
Shake firmly with the cap on, then press the tip on scrap paper several times to saturate it, as Posca’s FAQ advises (Posca FAQ). Posca also warns that storing markers in high heat can make the paint too fluid. Flip reversible tips on the PC-3M and PC-5M when one end is worn or stained. For a full Posca overview, see Posca markers.
Posca sizes on Amazon
One verified listing for each main size, smallest to largest.
-
Posca PC-5M paint markers, 8 count
The PC-5M in eight colors: the size to start with.
- 1.8 to 2.5 mm
- 8 colors
-
Posca PC-1MR paint markers, extra fine 0.7 mm, soft color 8 pack
The calibrated 0.7 mm tip for precise lines.
- 0.7 mm
- 8 colors
-
Posca PC-1M paint markers, extra fine 0.7 mm, 8 pack
The soft 0.7 mm bullet for details on rocks and wood.
- 0.7 mm
- 8 colors
-
Posca PC-3M paint markers, fine 0.9 to 1.3 mm, 8 pack
The writing size, with a reversible fine tip.
- 0.9 to 1.3 mm
- 8 colors
-
Uni Posca PC-7M water-based paint marker, broad 4.5 to 5.5 mm, black
The broad bullet for bold lines.
- 4.5 to 5.5 mm
- Black
-
Uni Posca PC-17K full range, all 8 colours
The 15 mm extra broad Posca in eight colors.
- 15 mm
- 8 colors
Each pick links to an Amazon listing we checked by hand. Prices, colors and pack sizes change on Amazon, so check the listing before you buy. As an Amazon Associate we earn from qualifying purchases.
Questions people ask
Why are POSCA markers so expensive?
Posca has not published a cost breakdown. Likely factors are the pigment paint, the valve and mixing ball inside every pen, reversible and replaceable tips on several sizes, and manufacture in Japan, which the PC-5M page states. Wide pens such as the PC-17K hold far more paint, so they cost more per pen.
Do Posca Pens rub off?
On porous surfaces such as paper, wood, cardboard, fabric and stone, Posca says its paint is permanent once dry. On smooth, non-porous surfaces such as glass and glazed ceramic it is erasable and can rub or wash off, which Posca describes as a feature for correcting mistakes. To protect work on smooth or handled surfaces, Posca suggests a water-based spray varnish.
What type of paint pens are waterproof?
Oil-based paint markers, such as Sharpie oil-based and Uni Paint, are the most water resistant on slick surfaces like glass, metal and plastic. Water-based paint markers such as Posca are water resistant on porous surfaces once dry, but can wash off smooth surfaces. Sealing with a clear varnish improves water resistance for either.
Why is POSCA so expensive?
Partly because of what you are comparing it with: Posca is sold per pen, while budget brands sell large boxes at a low price per pen. Posca scored highest overall among pump-action markers in Sarah Renae Clark’s comparison, which keeps demand high. To lower the cost, buy multipacks of one size or a set rather than singles, and replace worn tips instead of whole pens where Posca sells replacement tips.
What type of paint are POSCA markers?
Posca markers use water-based paint with stable pigments, which Posca says can be applied to all materials. People often call them acrylic markers. The PC-5M page describes the paint as water-based, mixable and layerable, quick drying and with strong UV resistance, and says creations can be protected with a fixative varnish.
Sources
Last reviewed 2026-10-12. Specs and availability change; check the listing before you buy.