Thermal label guide
What is a 100×150 mm thermal label?
The 100×150 mm thermal label is the most common shipping label size on roll thermal printers. Marketplaces and courier companies accept this size as the standard so that the barcode and address block stay legible. Because the thermal printer senses the label's width and length from the paper width, page margins and scaling are the most critical part of the job here.
A4 paper, on the other hand, is 210×297 mm; that is roughly twice the area of a 100×150 label. When a shipping label prepared for A4 is sent straight to a thermal printer, it is shrunk, centered or split across pages; because the barcode's size and position change, readers sometimes fail to recognize the label.
Why is an A4 shipping label converted?
The shipping label that comes out of a marketplace panel is usually a PDF prepared for A4. When you print this file as it is on a thermal printer, the printer tries to fit the content into the label size. This automatic scaling shrinks the barcode; when the space around the barcode narrows, the reader cannot decode it.
The conversion crops the label, places it on a 100×150 mm canvas and preserves the spacing it needs. The goal is not to decorate the label but to keep the barcode at the size and in the position where it was first produced. That is why the converter moves the content as little as possible and applies only the cropping and scaling that are needed.
Which marketplaces' labels are supported?
Marketplaces such as Trendyol, Hepsiburada, N11, Dolap and Gardrops usually offer the shipping label as an A4 PDF. Some panels place several labels on a single page; others put the label in the middle of the page and leave wide margins at the edges. The converter handles both cases: on a page with a single label it crops the surrounding space, and on a page with several labels it isolates the relevant one.
If the label is produced very close to the edge of the A4 page or with several labels overlapping, a test print after the conversion is the fastest way to check. That way, you see that the barcode and the address block sit exactly right before you print.
Barcode quality and readability
For a barcode to be read, resolution, contrast and the space around the barcode work together. If resizing blurs the barcode lines, the reader cannot tell the edges apart; that is why the safest approach is to leave the barcode at its original size as much as possible.
This tool focuses on printing the label close to the thermal printer's native resolution; the barcode is not redrawn and the page is not converted back to an image.
Print quality and color
Most thermal label printers print in one color: black. You should not expect a colored logo or colored warning on a shipping label; keeping the barcode black and the background white is essential for readability. The need for colored labels comes up mostly with branded product labels and shelf labels.
If you want color, there are two routes: transfer printers that produce colored thermal labels, or using label paper in a laser or inkjet printer. For shipping labels, the safest choice is plain black-and-white printing; that way readers pick up the contrast and the white space around the barcode more easily.
When is an 80×120 mm thermal label used?
The tool produces not only 100×150 mm but also 80×120 mm output. This size is preferred for small packages and shipments that should take up less space on the box. The barcode quality stays the same; because the label area narrows, the address block and tracking number sit more tightly.
If the marketplace label comes with wide margins on the A4 page, 80×120 mm output is enough. If the recipient's address is long, the courier company wants extra space or the label reader struggles to read the barcode, 100×150 mm is the safer choice. If you are not sure which size fits, do the first run with a single label and send the output through the printer.
150 × 100 mm support
The same label size is called 100×150 or 150×100 depending on where it is used; the two are rotated versions of the rectangle. On roll printers the width is usually 100 mm and the length 150 mm, so the label mostly goes by the name 100×150. Some marketplace panels and printer drivers list the same size as 150 x 100.
Whichever name you see, you can select 100 × 150 mm in the tool's output size option; the converter places the label on this canvas. If your roll is 80 mm wide, choosing the 80×120 mm output is more accurate.
Choosing a printer and supplies
The most common hardware for shipping labels is a roll thermal printer with 203 dpi resolution; this resolution is enough for the barcode and address text. 300 dpi models print more sharply, but the printer price and the supply cost go up. Direct thermal printers need no ink, yet the paper can fade over time; for documents you will store for a long time, a transfer printer is preferred.
With supplies, the roll size and the paper coating are decisive: for shipping labels you need a 100×150 mm roll, thermal label paper with a coated outer surface, and a core diameter that fits the printer. Before you buy a barcode label printer, check the roll width, the core size and your daily print volume; when the printer, the label roll and the paper do not match each other, barcode drift begins.
Checklist after the conversion
Trying the first print with a single label after the conversion is the fastest way to catch a possible drift before printing in bulk. Check these four points:
- Is the space around the barcode preserved? Readers cannot decode the barcode when this area narrows.
- Are the address block and tracking number complete, with nothing cropped?
- Is 'actual size' or '100%' selected in the printer driver? The 'fit to page' option breaks the scale.
- If you chose 80×120 mm, confirm in a test print that the text does not overflow.
Privacy and file security
A shipping label contains personal data such as the recipient's name, address and phone number. Access to your file is used only to complete the job; you can find the retention periods in the FAQ.