Label stock
25.4 × 12.7 mm labels
Exactly one inch by half an inch, and the size at which most people first discover that their naming convention is too long.
The size the 1.5 mL tube decides
A 1.5 mL microcentrifuge tube has an 8.5 mm barrel, giving about 27 mm of circumference. A 25.4 mm label wraps that with a small gap rather than an overlap, which matters more than it sounds: an overlapping wrap has a step, and a step catches on rack walls and on the fingers of whoever is pulling tubes out of a cold block.
The half-inch height is the usable straight run before the tube starts tapering toward the cone. Going taller does not gain a line of text; it gains a strip of label that is no longer in contact with the tube, and that strip is where the label starts to lift.
What this size is
- In inches
- 1 × 0.5 in. An inch size by origin: 25.4 × 12.7 mm is the exact conversion of it, with nothing rounded.
- Vessels it wraps
- Anything from a 1.5 mL microcentrifuge tube upwards, so also a 2 mL cryovial, a 50 mL conical tube and a GL45 reagent bottle. The tightest of those has a usable band of about 26 × 13 mm, which this label fits inside.
- Die-cut sheets
- No stock sheet in the editor is cut to this size. On plain paper it packs 154 per A4, 168 per Letter, cut by hand along printed marks.
- Roll stock that carries it
- 25.4 mm, 38.1 mm, 50.8 mm, 57 mm, 62 mm, 76.2 mm, 101.6 mm. The narrowest that takes it is 25.4 mm, and a roll narrower than the label is reported as an error rather than trimmed.
What fits on a 25.4 × 12.7 mm label
| Type size | Lines | Plex Sans | Barlow Condensed | Atkinson Hyperlegible | Plex Mono | Space Mono | Courier Prime |
|---|---|---|---|---|---|---|---|
| 4.5 pt | 5 | 30 | 42 | 30 | 24 | 24 | 24 |
| 5 pt | 5 | 27 | 38 | 27 | 22 | 21 | 22 |
| 6 pt | 4 | 23 | 31 | 23 | 18 | 18 | 18 |
| 7 pt | 3 | 19 | 27 | 19 | 15 | 15 | 15 |
| 8 pt | 3 | 17 | 23 | 17 | 13 | 13 | 13 |
| 10 pt | 2 | 13 | 19 | 13 | 11 | 10 | 11 |
Where the naming convention breaks
Twenty-three characters at 6 pt sounds generous until a real sample name goes into it. “HEK293T-shCTRL-p12-2026-09-13” is twenty-eight characters on its own, with nothing left for concentration, buffer or owner. The usual response is to drop to 5 pt, which buys four more characters per line and costs legibility on a frosted tube under a hood.
The better response is to decide which fields belong on the vessel and which belong in the record. A tube needs enough to be found and enough to not be confused with its neighbour. Passage number, construct and date are all record fields that a short identifier can point to.
A condensed face buys more than shrinking does. Barlow Condensed fits about 38% more characters than Plex Sans at the same point size, measured against the same string, so 6 pt condensed holds roughly what 4.5 pt regular would — at a stroke height the printer can still resolve.
Common questions
- How many 25.4 × 12.7 mm labels fit on an A4 sheet?
- No die-cut A4 sheet is commonly cut to this size, but the editor packs 154 of them onto a plain A4 sheet and 168 onto Letter, with cut marks printed for each. For anything beyond a handful that is usually cheaper than buying die-cut stock, at the cost of cutting by hand.
- Will this size fit a 2 mL cryovial?
- It will go on, but it is not the right size for one. A 2 mL cryovial has a wider barrel — about 12.5 mm — so a 25.4 mm label leaves a visible gap where frost gets under the leading edge. 28.6 × 12.7 mm is the size cut for that vessel.
Open it in the editor
The editor loads at 25.4 × 12.7 mm with a worked example in place. It runs entirely in your browser: nothing you type is uploaded, and there is no account to make.
Last reviewed 2026-09-13.