A roll label is not defined by its size alone. For the roll to fit the printer or the applicator, run without jams and deliver the label in the right position, six data points must be fixed: label size, gap between labels, core, outer diameter, unwind direction and number of labels per roll. This guide explains each one and what happens when it is missing.
1. Label size
Size is stated as width by height in millimeters, always in that order: width is the dimension across the roll and height is the dimension in the unwind direction. A 100 × 50 mm label comes off the roll 100 mm wide and advances 50 mm per label; a 50 × 100 mm label is the same surface turned sideways and needs a different die and a different roll.
Non-rectangular shapes (circle, oval, rounded corners or special die) are measured by their bounding rectangle. Also state the corner radius when there is one; 2 mm is the usual value so the corner does not lift on curved containers.
2. Gap between labels
This is the strip of liner left between one label and the next. The standard value is 3 mm; the minimum for applicators and printers with a gap sensor is 2 mm. With a smaller gap the sensor cannot tell the end of one label from the start of the next, and the printer loses registration or skips labels.
When there are several labels across the roll, there is also a side gap between columns, normally 2 to 3 mm. By default we deliver one label across; two or more across only when the applicator supports it.
3. Core
The core is the cardboard tube the label is rewound onto; it is specified by its inner diameter. The three standard values are 1" (25 mm) for desktop printers, 1.5" (38 mm) for some mid-range models and 3" (76 mm) for industrial printers and automatic applicators. The right value is in the manual of your equipment; a wrong core simply does not fit the spindle or wobbles on it.
4. Maximum outer diameter
This is the total diameter of the finished roll, limited by the capacity of the roll holder. Desktop printers usually accept up to 4" or 5" (100 to 127 mm); industrial printers, 8" (200 mm); applicators, 8" or larger. By default we rewind to 6" (150 mm) for desktop and 8" (200 mm) for applicators. A larger diameter means fewer roll changes, but only if it fits the equipment.
The roll in a diagram
- Core (inner diameter)
- 1" (25 mm), 1.5" (38 mm) or 3" (76 mm), depending on the applicator or printer.
- Maximum outer diameter
- Defined by the capacity of your equipment. Standard: 6" (150 mm) for desktop printers and 8" (200 mm) for applicators.
- Unwind direction
- Position 1 to 8: which edge of the label comes off first and whether the label is wound outside or inside.
- Labels per roll
- Result from the label size, the gap and the outer diameter; they are stated on the quote.
- Gap between labels
- 3 mm standard; 2 mm minimum for applicators with a gap sensor.
- Labels across
- One across as standard; two or more across the roll width when the applicator allows it.
- Sheet presentation
- Letter or legal sheets with die-cut, for hand application or laser printing.
5. Unwind direction
It states which edge of the label comes off the roll first and whether the label is wound outside or inside the roll. It is expressed with a number from 1 to 8: in positions 1 to 4 the label is wound outside and in 5 to 8, inside. The arrow in each pictogram marks the top of the label.
- 1 and 5: top first. The upper part of the design comes out first.
- 2 and 6: bottom first. The design comes out inverted relative to the feed direction.
- 3 and 7: right side first.
- 4 and 8: left side first.
Desktop and industrial printers almost always accept position 1 or 2 wound outside. Automatic applicators are stricter: the position depends on how the application head is mounted relative to the container, and a label rewound in the wrong position lands sideways or upside down on the product. If your applicator uses a different numbering, send the pictogram: the drawing prevails over the number.
6. Labels per roll
They are not chosen at will: they result from geometry. The usable length of liner that fits between the core and the outer diameter is calculated from the material thickness, and that length is divided by the label height plus the gap. That is why a 50 × 25 mm label on a 1" core and 4" diameter fits around a thousand pieces, while a 100 × 150 mm label on the same roll does not reach two hundred. The quoting tool makes this calculation with the thickness of each material and states it on the quote; if you need a fixed quantity per roll, we adjust the outer diameter.
Checklist
- Width × height in millimeters and label shape.
- Gap between labels (3 mm standard, 2 mm minimum).
- Core: 1", 1.5" or 3".
- Maximum outer diameter your equipment accepts.
- Unwind direction 1 to 8 (or the pictogram of your applicator).
- Labels across and, if required, a fixed quantity per roll.
- Printer or applicator model: with it we verify the six points above.
With that data, the quoting tool draws the roll exactly as it will be produced and the quote includes the full specification on its technical sheet.
