Circumference, label width and overlap on a wrap label

# How to calculate a wrap label size > The arithmetic behind a wrap label: circumference, overlap versus seam gap, tapered containers, pattern repeats and the errors that cause misfits. Pillar: label-sizing · Updated: 2026-11 **Our view.** Two formulas cover almost every wrap, and they are not interchangeable: an overlap wrap is circumference plus a few millimetres, a gap wrap is circumference minus a few. Choose the wrong one and the label either buckles over itself or leaves a strip of container showing at the back of every unit. A wrap label is a rectangle bent around a cylinder, so one dimension is not a length at all — it is a circumference. That single fact explains most badly sized wraps. This page covers the arithmetic, the two wrap styles, and the shapes where the formula stops working. ## The two formulas ``` Overlap wrap: width = (π × diameter) + overlap Gap wrap: width = (π × diameter) − gap ``` | Wrap style | Formula | Result on a 73 mm jar | |---|---|---| | Overlap, 4 mm | 229.3 + 4 | 233 mm | | Butt join, 1 mm gap | 229.3 − 1 | 228 mm | | Visible gap, 3 mm | 229.3 − 3 | 226 mm | Which one you need depends on the artwork and the application: - **Overlap** suits a continuous colour or a pattern that can afford to repeat over itself at the back. It is the safer choice for hand application, because a small drift still leaves no gap. - **Gap** suits a design with a defined start and end, or a container where a visible seam line is part of the look. It requires more accurate application. - **Butt join** is a gap wrap with almost no gap; it looks best and tolerates the least drift.

Width is a circumference plus an overlap, not a panel width.

## Measuring the circumference Three methods, in order of accuracy: 1. **Soft tape around the body.** Read the number where the tape overlaps itself. Do it twice, at 90° to each other, and use the larger figure. 2. **Calipers plus π.** Measure the diameter at the label position, multiply by 3.1416. Accurate on a true cylinder, wrong on anything oval or tapered. 3. **Paper strip and a ruler.** Wrap a strip, mark the overlap point, lay it flat and measure. Useful when you have no soft tape. A tape stretched tight reads short; one held loose reads long. On a 230 mm circumference, a 2 mm measurement error is under 1% — but it is the same order as the overlap, which is why the overlap exists. ## Tapered containers On a cone or a tapered bottle, the top and bottom circumferences differ, so the label is a trapezoid rather than a rectangle. ``` top width = (π × top diameter) + overlap bottom width = (π × bottom diameter) + overlap height = slant height of the label area, not vertical height ``` Worked example — a tapered jar, 70 mm at the top, 78 mm at the bottom, label area 55 mm tall on the slant: | Measurement | Value | |---|---:| | Top circumference | 219.9 mm | | Bottom circumference | 245.0 mm | | Label width, top (4 mm overlap) | 224 mm | | Label width, bottom | 249 mm | | Height | 55 mm | That is a 25 mm difference across the height. A rectangular 235 × 55 mm label would wrinkle at the bottom or lift at the top on every unit — this is the case where a custom dieline pays for itself. ## Oval and square containers For an oval bottle, π × diameter is meaningless: the diameter varies with the angle. Wrap a tape around the widest point and read the circumference directly. For a square or hexagonal container, the perimeter is the sum of the sides, plus the corner radius correction: ``` perimeter ≈ 4 × side − (8 − 2π) × radius ``` In practice, wrap a tape. The formula is included only to explain why a 60 mm square bottle does not take a 240 mm label — the rounded corners remove material from the path. ## Pattern repeats and seams If the artwork repeats, the repeat has to fit the label width exactly, or the pattern will break at the seam. ``` repeat count = round(label width ÷ repeat size) adjusted width = repeat count × repeat size ``` Example: a 226 mm gap wrap with a 40 mm repeat. 226 ÷ 40 = 5.65, so five repeats need 200 mm and six need 240 mm. Neither is 226. The options are to adjust the repeat to 37.7 mm (five repeats), accept a deliberate mismatch hidden at the back, or design the seam as a feature — a vertical rule or a colour block that reads as intentional. This is the single most common reason a wrap design comes back from proofing. ## Tolerance stacking Three tolerances add up on a wrap: | Source | Typical | |---|---| | Container diameter variation | ±0.5 mm → ±1.6 mm circumference | | Cutting tolerance | ±0.5 mm | | Application drift | 1–3 mm hand, ±0.5 mm machine | Worst case on a hand-applied wrap: about 5 mm. That is why an overlap of 3–5 mm is standard — it absorbs the stack without showing a gap. A gap wrap on the same container needs the drift to be smaller than the gap, which is why it is usually machine-applied. ## What this means for buyers **Say whether you want an overlap or a gap.** They produce different widths from the same measurement, and the printer cannot guess which look you approved. **Measure at the label position, not the widest point.** A bottle that bulges in the middle takes a different wrap at the shoulder. **Round numbers are suspicious.** A 240 mm wrap on a 75 mm bottle is a deliberate overlap, not a measurement. **For anything tapered or oval, send a photo with a tape around it.** It removes an entire round of proofing. ## Quick answers **How do I calculate the width of a wrap label?** Measure the circumference with a soft tape, or multiply the diameter by 3.1416. For an overlap wrap add 3 to 5 mm; for a gap wrap subtract 2 to 3 mm. The two methods give different widths for the same container. **What is the circumference of a 75 mm bottle?** 235.6 mm. Multiply the diameter by pi: 75 times 3.1416 equals 235.6. Add 4 mm of overlap for a wrap of about 240 mm, or subtract 3 mm for a gap wrap of about 233 mm.