Label stock

63.5 × 38.1 mm labels

Four millimetres taller than the 24-up cell, and that is the whole difference between 24 labels on a page and 21.

Open this template in the editor63.5 × 38.1 mm

63.5 × 38.1 mm (2.50 × 1.50 in). The inner outline is the 1 mm safe area. Wraps a 50 mL conical tube or a reagent bottle.

A vessel size that collides with a sheet size

2.5 × 1.5 inches is a tube measurement. A 50 mL conical has about a 30 mm barrel, roughly 94 mm around, with perhaps 75 mm of straight run before the cone. A 63.5 mm label covers two thirds of the circumference — enough to read most of it without rotating the tube far, and far enough from meeting itself that the ends never have to overlap.

The awkwardness is what happens on paper. 38.1 mm is 4.2 mm taller than the 33.9 mm that makes eight rows fit A4, so a sheet cut to this size gets seven rows instead of eight. That is three labels per sheet, about 12% of the page, given up to gain four millimetres of label height.

What this size is

In inches: 2.5 × 1.5 in. An inch size by origin: 63.5 × 38.1 mm is the exact conversion of it, with nothing rounded.
Vessels it wraps: Anything from a 50 mL conical tube upwards, so also a GL45 reagent bottle. The tightest of those has a usable band of about 88 × 55 mm, which this label fits inside.
Die-cut sheets: A4 · 21-up · 63.5 × 38.1 mm — 21 per A4 sheet.
Roll stock that carries it: 76.2 mm, 101.6 mm. The narrowest that takes it is 76.2 mm, and a roll narrower than the label is reported as an error rather than trimmed.

What fits on a 63.5 × 38.1 mm label

Type size	Lines	Plex Sans	Barlow Condensed	Atkinson Hyperlegible	Plex Mono	Space Mono	Courier Prime
4.5 pt	19	80	111	81	64	63	64
5 pt	17	72	100	73	58	56	58
6 pt	14	60	83	60	48	47	48
7 pt	12	51	71	52	41	40	41
8 pt	10	45	62	45	36	35	36
10 pt	8	36	50	36	29	28	29

Fourteen lines at 6 pt against twelve on the 33.9 mm cell — the extra height is two more lines, not two more characters. Figures are characters per line, for 63.5 × 38.1 mm. Measured against the string “Tris-HCl 1 M pH 8.0 25 mg/mL 2026-08-24 GS lot B-204 store 4 C”, which is representative of laboratory text rather than of prose.

Choosing between this and the 33.9 mm sheet cell

Labelling tubes, buy this: The extra height is contact area on a curved surface, and contact area is what keeps a label on a tube that gets spun, chilled and handled with gloves.
Labelling flat things, buy the shorter one: On a box lid or a rack the four millimetres gain nothing, and you get three more labels per sheet for the same paper.
Printing from a roll, the difference disappears: Roll stock is priced by length and die-cut to size. There is no page to waste, so pick the size that suits the vessel and ignore the sheet arithmetic entirely.
Mixing both, standardise on one: Two sizes of blank stock in one cupboard reliably becomes two sizes loaded in the wrong printer. If the lab does mostly tubes, one size for everything costs less in wasted sheets than the confusion costs in reprints.

Common questions

Does this size fit a 15 mL conical?: It wraps, but it is generous. A 15 mL conical has about 53 mm of circumference, so a 63.5 mm label overlaps itself by around 10 mm. That overlap is a step that catches in racks. 38.1 × 19.05 mm suits a 15 mL tube better.
Why does an A4 sheet only hold 21 of these?: Seven rows of 38.1 mm is 266.7 mm, and adding an eighth would need 304.8 mm — more than A4's 297 mm before any margin. Three columns times seven rows is 21.

Open it in the editor

The editor loads at 63.5 × 38.1 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.

Open the 50 ml conical tube template

Last reviewed 2026-09-13.