Shipping label sizes: 4x6, A6, A4 and Letter
What fits what, and the A4-versus-Letter trap that wastes a sheet every time.
There are two ways to put a label on a parcel: a thermal printer that prints one label at a time on a roll, or an ordinary printer and a sheet of paper you cut up. Most small sellers start with the second and move to the first.
The sizes are worth understanding either way, because the wrong choice wastes either paper or money.
The sizes that matter
100 x 150 mm, or 4 x 6 inches. The thermal standard. Almost every shipping label you have ever received was this size. It is what carriers print, what label rolls come in, and what a desktop thermal printer expects.
A6, 105 x 148 mm. Within a few millimetres of 4 x 6, and the standard size for integrated peel-off sheets sold across Europe. Slightly wider and slightly shorter than the thermal size, which turns out to matter.
150 x 100 mm. The same stock fed landscape. Useful when the address is long or the parcel is wide and flat.
100 x 75 mm, or 4 x 3 inches. Sold for small packets and polybags. Fine for an address, too small for a customs declaration.
How many fit a sheet
At true size, with no scaling. Squashing a label to make the arithmetic work produces something that is no longer the size it claims to be, and thermal stock in particular is unforgiving about that.
| Label | Per A4 | Per Letter |
|---|---|---|
| 100 x 150 mm | 2 | 2 |
| A6 105 x 148 mm | 4 | 2 |
| 150 x 100 mm | 2 | 2 |
| 100 x 75 mm | 6 | 6 |
The A4 versus Letter trap
A4 is 210 x 297 mm. US Letter is 216 x 279 mm. Letter is 6 mm wider and 18 mm shorter, and that second number causes real waste.
Two A6 labels stacked are 296 mm tall. That fits inside A4’s 297 mm with a millimetre to spare. It does not fit Letter’s 279 mm.
So a four-up A6 layout designed for A4 and printed on Letter loses the entire bottom row off the page. Usually there is no warning, and you notice after printing thirty sheets.
If you are in the United States, Canada or Mexico, your printer holds Letter. Almost everywhere else holds A4. Pick a layout that knows which one you have.
When to buy a thermal printer
Rough arithmetic. A desktop 4 x 6 thermal printer costs somewhere around a hundred dollars or pounds. Direct thermal labels cost a few cents each and need no ink at all, which is the real saving: inkjet cartridges are the expensive part of printing at home.
If you post more than a handful of parcels a week, it pays for itself within months. Below that, plain paper and clear tape works fine and costs nothing to start.
Two things to know if you buy one:
- Direct thermal, not thermal transfer, for shipping labels. Direct thermal needs no ribbon. The print fades over months in sunlight, which does not matter for a parcel in transit.
- 203 dpi is the normal resolution and is plenty for text and barcodes. 300 dpi exists and is worth it only for very small type.
Printing on plain paper
Perfectly acceptable, and how most sellers begin.
- Set the print dialog to margins: none. Browsers and printers both add margins by default, which shifts the label and can clip a barcode.
- Choose the correct paper size in the dialog. Firefox and Safari ignore the size a web page requests, so pick it by hand there.
- Print at 100%, never “fit to page”. Scaling changes the barcode’s module width, and a scaled Code 128 may not scan.
- Tape over the whole label with clear packing tape. It waterproofs it and stops the edges lifting.
Barcodes and label size
A Code 128 barcode needs a quiet zone, meaning clear space at each end, and it needs its bars to stay crisp. Both suffer when you shrink a label.
If you are using the compact 100 x 75 mm size, check that the barcode still scans before you print a hundred of them. On the smaller sizes there is also no room for a customs declaration, so an international parcel needs the form attached separately.
What this site does
Labelbench offers six templates across those sizes, works out how many fit at true size on the sheet you actually have, and warns when the template you picked has no room for a customs declaration that the route requires.