Label stock

101.6 × 50.8 mm labels

Four inches by two: the size a thermal printer is most likely to already have loaded.

Open this template in the editor101.6 × 50.8 mm

101.6 × 50.8 mm (4.00 × 2.00 in). The inner outline is the 1 mm safe area. Wraps a reagent bottle.

A shipping size that labs inherited

4 × 2 inches is the standard shipping label die cut, and the volume behind that made it the cheapest and most widely available roll stock in every material a label printer can take. Desktop thermal printers are built around a 4 inch print width for the same reason, which is why 101.6 mm is both the label width and the practical maximum on that class of machine.

Laboratories ended up on it by availability rather than by design. It is larger than almost anything in a lab needs, but when a printer arrives with a roll of it and replacements are a day away, it becomes the default for box lids, equipment, waste containers and secondary containment.

What this size is

In inches: 4 × 2 in. An inch size by origin: 101.6 × 50.8 mm is the exact conversion of it, with nothing rounded.
Vessels it wraps: A GL45 reagent bottle and nothing smaller. Its usable band is about 200 × 90 mm, which this label fits inside.
Die-cut sheets: Letter · 10-up · 101.6 × 50.8 mm — 10 per Letter sheet.
Roll stock that carries it: 101.6 mm. The narrowest that takes it is 101.6 mm, and a roll narrower than the label is reported as an error rather than trimmed.

What fits on a 101.6 × 50.8 mm label

Type size	Lines	Plex Sans	Barlow Condensed	Atkinson Hyperlegible	Plex Mono	Space Mono	Courier Prime
4.5 pt	26	130	180	131	104	102	104
5 pt	23	117	162	118	94	92	94
6 pt	19	98	135	98	78	76	78
7 pt	16	84	115	84	67	65	67
8 pt	14	73	101	74	58	57	58
10 pt	11	58	81	59	47	46	47

The largest capacity on this site: 98 characters across and 19 lines down at 6 pt. Figures are characters per line, for 101.6 × 50.8 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.

What this size is genuinely good for

Hazardous waste containers: Waste labels carry a contents list that grows as the container fills, plus accumulation dates and a hazard classification. They need the room, and they need to be readable from outside a fume hood.
Secondary containment: A tray or a bund holding several vessels needs one label describing what is in the tray. That is a summary of several things, which is more text than any vessel label carries.
Equipment and instrument panels: Flat, wiped down, read while standing. A large polyester label with a large identifier is exactly right.
Freezer box lids: A 4 × 2 inch label covers most of a standard 2 inch cryobox lid and can carry a grid map rather than just a box number.

Common questions

Will a 4 × 2 inch label wrap a bottle?: On a large bottle, yes — a 1 L Duran has around 95 mm of barrel, roughly 300 mm around, so a 101.6 mm label covers about a third. On anything smaller than a 500 mL bottle it will meet itself, and a label that overlaps its own leading edge lifts there first.
Is direct thermal good enough at this size?: It depends entirely on the life of the label, not on its size. Direct thermal is fine for a waste container that is filled and collected within weeks. It is not fine for equipment, freezer stock or anything that meets solvent, heat or sunlight, where the image fades while the label stays put.

Open it in the editor

The editor loads at 101.6 × 50.8 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 101.6 × 50.8 mm roll label template

Last reviewed 2026-09-13.