Pen Point Sizes, 0.5 vs 0.7 vs 1.0 mm
The millimeter figure on a ballpoint or gel pen is the ball diameter, so 0.5 mm writes finer than 0.7 mm, and 1.0 mm is usually sold as medium.
By Antonio SmithamContributing writer.
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The short answer
When a pen says 0.7 mm, it means the small ball in the tip is 0.7 millimeters across. A smaller ball lays down a thinner line, so a 0.5 mm pen writes finer than a 0.7 mm pen, and a 1.0 mm pen writes bolder still.
The number is the ball, not the line. How wide the line comes out also depends on the ink and how hard you press, so two 0.7 mm pens from different brands can look different on paper.
What the names mean
Makers pair the size with a word, and the words are not fully standard. Pilot's Better ballpoint, for example, comes in two sizes:
| Pilot Better ballpoint | Point size |
|---|---|
| Fine | 0.7 mm |
| Medium | 1.0 mm |
Pilot's G2 gel pen comes in four named sizes (ultra fine, extra fine, fine and bold). Because one brand's "fine" can be another brand's "extra fine," compare the millimeter figure rather than the word.
Ballpoint balls range from 0.28 mm to 1.6 mm, and gel pen balls are usually between 0.3 and 1.2 mm. The everyday sizes are 0.5, 0.7 and 1.0 mm.
0.5 vs 0.7 pen
- 0.5 mm: a fine, crisp line. Good for small handwriting, planners, forms with narrow boxes and narrow-ruled paper.
- 0.7 mm: a slightly heavier line that is easier to read at a glance. The size Pilot calls fine on its Better ballpoint.
- 1.0 mm: a bold line for signatures, labels and large handwriting.
If your handwriting is small or you write in tight spaces, start with 0.5 mm. If lines look faint or scratchy, try 0.7 mm.
Ballpoint vs gel pen
The ink is the real difference:
| Ballpoint | Gel | |
|---|---|---|
| Ink | Oil-based paste of dye in solvents | Pigment suspended in a water-based gel |
| Ink body | Paste, about 25 to 40 percent dye | Thicker and more opaque |
| On slick surfaces | Less visible | Shows up more clearly |
| After drying | Varies by ink | Many gel inks resist water |
Rollerball pens use a thin water-based ink, and hybrid inks sit between ballpoint and rollerball in thickness. Hybrid inks also dry faster than gel ink, which helps anyone whose hand drags across fresh lines.
Pick a gel pen when you want an opaque line that stands out, and a ballpoint for an everyday paste ink.
How we count
On Wiki Shopping, 61 ballpoint pens were listed under office products on October 26, 2026. Of those, 26 state a point size that we group: 15 at 1.0 mm, 9 at 0.5 mm and 2 at 0.7 mm. Point size is read from each listing; pens that do not state one, or state another size, are left out of the count. Size names and ranges come from the sources listed below.