Label stock
Thermal label sizes
A thermal roll's width is fixed by the printer; the label length is fixed by the die. Everything else follows from those two numbers.
Roll width, print width, label size
Three different dimensions get called “the size”. The roll width is the physical media. The print width is what the printhead can actually reach, which is narrower — the mechanism needs margin at both edges. The label size is the die-cut rectangle, which sits inside the print width.
Designing to the roll width rather than the print width is a common way to lose content at the edges. The printer will not warn you: it prints what it can reach and drops the rest.
Common laboratory thermal label sizes
| Label size | Inches | Typical use |
|---|---|---|
| 19.1 × 6.4 mm | 0.75 × 0.25 | PCR tubes and strips |
| 25.4 × 12.7 mm | 1 × 0.5 | 1.5 mL microcentrifuge tubes |
| 28.6 × 12.7 mm | 1.125 × 0.5 | Cryovials |
| 38.1 × 19.1 mm | 1.5 × 0.75 | 15 mL tubes, general samples |
| 50.8 × 25.4 mm | 2 × 1 | Reagent bottles |
| 63.5 × 38.1 mm | 2.5 × 1.5 | 50 mL tubes, buffer bottles |
| 76.2 × 50.8 mm | 3 × 2 | Media bottles, box lids |
Sensing, and why it matters to your design
- Gap sensing
- The printer detects the space between die-cut labels by shining light through the liner. Dense black printing near the gap can confuse it on some printers, and the whole roll goes out of registration.
- Black mark sensing
- A mark on the liner's back defines the label pitch. More robust than gap sensing on synthetic media, which can be translucent enough to defeat it.
- Continuous media
- No die cut at all; length is set by the driver. Flexible, and entirely dependent on the driver's length setting being right.
- Calibration after a media change
- Most printers need to be told the media has changed. Skipping it is a common cause of labels printing across the gap.
Common questions
- What is the most common thermal label size for labs?
- 25.4 × 12.7 mm for microcentrifuge tubes and 50.8 × 25.4 mm for bottles. Cryovials take 28.6 × 12.7 mm.
- Why is my thermal printer printing across the label gap?
- It has lost registration — usually because the media was changed without recalibrating, or because the driver's label size does not match the roll.
Last reviewed 2026-08-24.