Troubleshooting
Fix thermal label alignment
Almost every thermal label misprint comes from one of three things: the PDF page isn’t the label size, the print dialog is scaling, or the printer hasn’t learned the label gap. Make the page exactly the label size, print at Scale 100% with no margins, run the printer’s label calibration, and correct the last millimetre with a test label. Prepline handles the page size and the offset, and saves the offset per printer.
| What you see | Cause | Fix |
|---|---|---|
| Sides cut off | Page wider than the label (a sheet label sent to a roll) | One label per page at the label size |
| Tiny label, or two per sticker | Print dialog “Fit to page” / “Scale to fit” | Scale 100% (Actual size), paper = label size |
| Blank label between each | Printer thinks labels are longer (4 × 6 default, or gap not learned) | Set the paper height; run the gap calibration |
| Every label a little lower or to one side | This printer’s feed offset | Test label, measure two gaps, save the offset |
| Prints sideways | Narrow roll that feeds sideways (Dymo 30336) or wrong orientation | Turn the page 90° (Prepline: “Turn 90°”) |
| Faint or smeared bars | Darkness too high or low, or bars not on whole dots | Adjust darkness one step; use whole-dot bars |
The calibration that sticks
Printer calibration (holding the feed button) teaches the printer where each label starts. It doesn’t fix a printer that always prints 1.5 mm to the left. For that, print a label with a known frame and measure it:
- In Prepline, press Calibrate and download the test label: a frame exactly 2 mm inside each edge, with a crosshair and 1 mm ticks.
- Print it at Scale 100%. First check the frame size printed on the label (53.2 × 27.8 mm on a 2.25 × 1.25 in label). If it’s smaller, the dialog is scaling.
- Measure the gap from the left edge and from the top edge to the frame. 3.5 mm on the left means everything moved 1.5 mm right.
- Type the two gaps and save. Every later label for that printer moves back by exactly that much.
Printer by printer
- Rollo: hold the top button until it beeps to relearn the label after a roll change. Rollo settings
- Zebra GK/GX: hold Feed until two flashes, then let go. Set Media Type to “Labels with gaps”. Zebra settings
- Dymo: no calibration; choose the label number (30334, 30336) as the paper. Dymo settings
- MUNBYN / Phomemo / TSC: run the auto label-learning after each roll change and add the size as a custom paper. All printers
Questions
Why does my thermal printer print a blank label after every label?
It thinks the labels are longer than they are, usually because the paper size is still 4 × 6 in or the gap hasn’t been learned. Set the paper height to your label and run the printer’s label calibration.
Why are my labels shifted to one side?
Each printer feeds slightly differently. Print a test label with a frame 2 mm from each edge, measure the gaps, and offset future labels by the difference.
Why does my label print tiny in the corner?
The print dialog is shrinking a Letter page onto the label. Set Scale to 100% and choose the label size as the paper.
Updated November 9, 2026