The label is sized by the circumference
Pi times the diameter is the whole trick, and it is worth internalising how fast that grows. An eighth of an inch on the diameter is 0.393 in of extra label. A quarter inch is 0.785 in. If your overlap is a quarter of an inch and you switch to a bottle an eighth fatter, the overlap has already gone and you are into a gap. Sampling one bottle and ordering ten thousand labels off it is how that becomes expensive.
Erring long costs nothing visible. The extra disappears under the seam and the only sign is a slightly thicker overlap. Erring short shows on every single unit, in the same place, in a way the eye finds instantly. If the diameter you measured is uncertain, add to the overlap rather than trimming it.
Height is limited by where the glass stops being straight
A pressure-sensitive label is a flat sheet. It will conform to a cylinder in one direction and to nothing in the other. The moment the top edge reaches the shoulder, the label is being asked to lie flat on a compound curve and it responds by wrinkling, lifting at the corners, or both. The straight body height minus a little clearance top and bottom is the real ceiling, and it is usually less than people expect after they have looked at the bottle rather than measured it.
The bottom clearance earns its keep for a different reason. Bottles do not sit perfectly square on their bases, and a label run down to the heel makes every degree of that visible as a label that looks crooked when it is not.
Getting the roll count right
A roll of labels is a flat spiral, so the wound length is the annulus area divided by the material thickness: pi times the outside diameter squared minus the core diameter squared, all over four times the thickness. The thickness is the input people get wrong, because a label plus its adhesive plus the liner is thicker than the face stock alone. Stack ten labels with their liners, measure with a caliper, divide by ten.
| Input | What it does to the roll count |
|---|---|
| Outside diameter | Squared, so a small increase adds a lot of length |
| Core diameter | Subtracted as a square, so a big core costs more than it looks |
| Material thickness | Divides the whole thing — a 10 per cent error here is a 10 per cent error in the count |
| Gap between labels | Adds to the pitch, so short labels lose a larger share to it |
For labels laid out on a sheet rather than a roll, the arithmetic is a rectangular nest and that is the sheet nesting yield calculator. For cut vinyl coming off a wide roll, where the parts nest across the width as well as along it, use the vinyl and decal material calculator. A wound reel with a traverse and several lanes per layer is a different sum again — that is the cable reel capacity calculator.
What is not on this page
Nothing here says what must be printed on a label, how big any of it has to be, or how the contents have to be declared. Those rules are set by the agency that regulates your product and by state law, they differ by category, and they change. This page tells you how much paper the container needs.
Questions people ask
How much overlap should a wrap label have?
Enough to cover the variation you actually have, which you find by measuring several containers rather than one. The overlap is doing two jobs: hiding the joint, and absorbing the difference between the bottle you sampled and the bottle in front of you. If your measured diameters spread by a sixteenth of an inch, that is nearly two tenths of an inch of circumference spread, and your overlap has to be bigger than that before it is doing anything.
Why does my label not lie flat at the top?
Almost always because the top edge has reached the shoulder. A flat label conforms to a cylinder and not to a curve that bends two ways at once. Measure the genuinely straight part of the body, take a little off top and bottom, and that is the tallest label the container will take without fighting you.
How do I work out how many labels are on a roll I already have?
Measure the outside diameter of the wound roll, the core diameter, and the thickness of the label with its liner. The wound length is pi times the difference of the squared diameters, divided by four times the thickness. Divide that by one label plus the gap between labels. The thickness is the input worth measuring properly, because the count is directly proportional to it.
Front and back labels, or one wrap?
A pair leaves the container visible down both sides, which matters if the product is worth looking at, and it needs two applications instead of one. A wrap covers everything and hides the seam under itself. Dimensionally the difference is that a pair splits the circumference minus two gaps between two panels, so each panel is well under half the size of a wrap label.
Does this tell me what my label has to say?
None at all, and that is deliberate. Labelling is one of the most heavily regulated corners of small manufacturing, the rules differ by product type and by state, and they move. This page has no rule about what goes on a label, how net contents are declared, what counts as an acceptable fill, or how anything may be shipped. It measures containers, labels, cases and station times. The rules come from the agency that regulates your category and from a lawyer.