4x6 vs A6 Shipping Label: 3.4 mm Apart, Not Equal

The 4x6 vs A6 shipping label question looks like pedantry until a pallet gets refused at a distribution centre because the barcode sits 30 mm too low. A6 is 105 × 148 mm. Four by six inches is 101.6 × 152.4 mm. They are treated as one size class across the industry and they are not the same piece of paper, and the gap between those two facts is where rejected labels live.

Five beliefs about label size cost exporters money. Each one is answered below by what GS1 actually publishes, not by what a label vendor's blog says.

4x6 vs A6 shipping label sizes, side by side

A6 is 3.4 mm wider and 4.4 mm shorter than a 4 × 6 inch label. The areas are within half a percent of each other, which is exactly why the two get treated as interchangeable — and why the substitution fails at the edges rather than in the middle.

A6 and 4 × 6 are one size class and three different pieces of paper, and all three get called "four by six" somewhere in the supply chain. GS1's own Logistic Label Guideline demonstrates the ambiguity in a single document: section 7 offers the compact label as "A6 (105 mm x 148 mm) or 4 x 6 inch", while Appendix B titles the same layout "A6 / 4.1 x 5.8 inch" — the honest conversion of 105 × 148 mm.

Myth 1: "A6 and 4 × 6 are the same label"

They are the same choice, not the same medium.

GS1 lists exactly two recommended sizes for a logistic label. The compact label is A6 (105 mm × 148 mm) or 4 × 6 inch, suitable when only the SSCC, or the SSCC plus limited additional data, is encoded. The large label is A5 (148 mm × 210 mm) or 6 × 8 inch, suitable when additional trade item data is needed — the pallet case.

So at the level of "which layout do I use", the 4x6 vs A6 shipping label decision has one answer for both. At the level of "which roll do I load", they are not the same thing, and a printer configured for one will clip or drift on the other. On a 4 × 6 template printed onto A6 stock, the extra 3.4 mm of width shifts content sideways and the missing 4.4 mm of height eats the bottom of the label — which is precisely where the SSCC barcode is supposed to be.

Myth 2: "Any size works as long as it scans"

Half right, and the wrong half is the expensive one.

GS1 does say the label may be any size, and lists the factors that drive the choice: the amount of data required, the X-dimension of the barcodes used, and the dimensions of the logistic unit being labelled. What it does not flex is the symbol itself:

The label can shrink. The barcode cannot follow it down. A 31.75 mm bar height plus human-readable interpretation plus quiet zones is a fixed budget, and once the data pushes past what fits at the minimum X-dimension, the answer is a bigger label, not a smaller symbol. GS1 also notes that an X-dimension at the higher end of the permitted range supports consistent scanning in difficult conditions — freezing, for example, degrades print quality — so squeezing to 0.495 mm to save space is a trade, not a free win.

Myth 3: "Put the label wherever there's a flat spot"

Placement is normative, and it is the rule most often broken by exporters who otherwise print a perfect label.

Two practical notes GS1 adds that rarely make it into a supplier's SOP. First, each pallet should carry at least one label, and two sides should be labelled with identical data so one is always visible regardless of whether the pallet is stored long-edge or short-edge out. Second, there is no rule about left, middle or right — but because most forklift operators are right-handed, placing the label to the right of each side is the most ergonomic to scan.

If your cartons carry printed shipping marks as well, the interaction between the two is its own discipline; the conventions are covered in export carton shipping marks.

Myth 4: "Concatenate the data to save space on the small label"

This one is explicitly forbidden in the exact case where people are most tempted to do it.

GS1 requires that the SSCC, defined by AI (00), shall always appear in the lowest barcode on the label. The SSCC can be alone or concatenated with other data in the same barcode — except that concatenation shall not be used with the SSCC on cartons and outer cases, or on A6 / 4 × 6 labels.

Read that twice if you print compact labels. On the exact format this article is about, the SSCC has to stand alone in its own symbol at the bottom of the label. If the data you wanted to concatenate does not fit as a separate symbol above it, you have outgrown the compact label.

Myth 5: "If it doesn't fit, reduce the font and the barcode"

The published escape route is the A5 label, not a compressed A6 one. A5 is 148 × 210 mm, or 6 × 8 inch in the same loose inch convention, and GS1 designates it for the case where trade item data joins the SSCC — typically pallet labels. GS1 also recommends sticking to standard paper sizes such as A5 or A6 rather than inventing a custom size, because custom stock is where printer misconfiguration and clipped symbols come from.

The decision is data-driven, and it takes about ten seconds:

Why this shows up as a returns problem, not a printing problem

A clipped or unscannable label does not usually get flagged as a label defect. It gets flagged as a receiving discrepancy, a missing pallet, or a short shipment — and the cost lands on the supplier as a chargeback weeks later, long after anyone can reconstruct which roll of stock was loaded that day.

The same failure mode runs through every dimension a factory publishes. A number that exists only in a spreadsheet is a number nobody checks: the label size in the print queue, the carton dimensions in the packing list, the product dimensions on the listing. Each one is fine until it silently disagrees with reality. The exporters who stop paying for this are the ones who put the measured value onto the artwork itself — the carton diagram showing where the label sits and how far off the base, the product image showing the real dimension snapped to the real edge — rather than trusting that everyone downstream reads the same table the same way. Numbers that came from a measurement survive the handoff; numbers assembled from what a similar drawing usually says do not. The related figures for the boxes themselves are in master carton dimensions for export, and the label sizes in circulation are collected on the standard shipping label sizes reference.

Next steps, in order

1. Measure the stock you actually have. Take a caliper to one label from each roll in the building. If it reads 105 × 148, it is A6, whatever the purchase order called it.
2. Match the template to the stock, not to the habit. One template per media size, named for the millimetres, never for the inch nickname.
3. Print a test label and measure the barcode. Bar height must be at least 31.75 mm before the human-readable line; X-dimension inside 0.495–0.94 mm.
4. Check placement on a real carton and a real pallet against the 32 mm / 19 mm and 400–800 mm / 50 mm figures above, with a tape measure, once.
5. Fix the packaging artwork so placement is drawn, not described. A carton drawing with the label zone dimensioned on it stops the argument with the packing line permanently — and the same logic applies to any dimension a buyer needs to trust, which is where a spec diagram built from measured values rather than from a stock photo earns its keep.
6. Re-check after any printer, stock or 3PL change. Those three events cause most label regressions.

Pre-print label checklist

• Media size verified with a caliper and recorded in millimetres
• Print template matches that media size exactly — no "close enough" substitution between A6 and 4 × 6
• GS1-128 bar height at least 31.75 mm (1.250 in), excluding human-readable text
• X-dimension between 0.495 mm and 0.94 mm; higher end chosen for cold-chain or rough handling
• Quiet zones at least 10X on both sides of every symbol
• SSCC is the lowest barcode on the label
• SSCC is not concatenated with other data on cartons, outer cases, or A6 / 4 × 6 labels
• Carton labels: bottom of barcode 32 mm from the natural base, 19 mm minimum from vertical edges
• Pallet labels: barcode 400–800 mm from the base, 50 mm minimum from vertical edges, two sides labelled with identical data
• Test label scanned from the distance and angle a receiving dock actually uses

FAQ

Is A6 the same as a 4x6 shipping label?

Not dimensionally. A6 is 105 × 148 mm and a 4 × 6 inch label is 101.6 × 152.4 mm, so A6 is 3.4 mm wider and 4.4 mm shorter. GS1 lists them as alternative expressions of the same compact label choice, which is why they are used interchangeably in specification documents — but printer media settings have to match the physical stock, not the size class.

What size is a 4x6 shipping label in mm?

101.6 × 152.4 mm exactly, since one inch is 25.4 mm. The commonly sold metric equivalent is 100 × 150 mm, which is 1.6 mm narrower and 2.4 mm shorter than the true inch size and shares its 1.5 aspect ratio.

What is the minimum barcode size on a shipping label?

For GS1-128 symbols on a logistic label, the minimum bar height is 31.75 mm (1.250 in), measured as bar height alone and excluding the human-readable interpretation, with an X-dimension between 0.495 mm and 0.94 mm and quiet zones of at least 10 X-dimensions. Those figures do not scale down when the label does.

How high should a barcode be placed on a pallet?

Between 400 mm (16 in) and 800 mm (32 in) from the base of the pallet, with the symbol and its quiet zones at least 50 mm (2.0 in) from any vertical edge. For pallets shorter than 400 mm, place the barcode as high as possible while still protecting it.

When should I move from an A6 label to A5?

As soon as the data goes beyond the SSCC and a little supporting information — GTIN, batch or lot, dates, quantities. On A6 and 4 × 6 labels the SSCC cannot be concatenated with other data, so extra content needs extra symbols, and extra symbols need the 148 × 210 mm A5 format rather than a compressed compact label.

Sources & References

• GS1 — Logistic Label Guideline, Release 1.3, Ratified July 2019 (sections 6, 7, 8 and Appendix B)
• GS1 — GS1 Logistic Label Guideline, Release 1.3 (standards library entry)
• GS1 — General Specifications (the normative source the Logistic Label Guideline cites for symbol size and placement)