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Neckline Calculator — Neckline Dimensions & Binding
Calculate neckline opening dimensions and binding strip length for various neckline styles.
How We Calculate This
The neckline opening is built from its real cut geometry, not by shrinking your body neck measurement. The opening width across the shoulders is set by the style (boat widest, V and crew narrowest), and the front contour is measured along the actual cut line.
The method
V-neck front = 2 × √((width÷2)² + drop²) — the two diagonals (Pythagoras).
Round / scoop / boat front = half-ellipse arc of half-width × drop.
Square front = width + 2 × drop (two sides + base).
The back is a shallow ~2cm scoop. The total opening is floored at (head + neck) ÷ 2 so it always clears the head.
Binding length = opening × 0.85 (knit), × 0.75 (ribbing), or × 1.00 + 2cm (woven bias).
Frequently Asked Questions
Measure around the base of your neck where a necklace would sit. The tape should be snug but comfortable. A typical women’s base-of-neck measurement is 34–38cm. This is the body measurement, not the finished garment opening.
For a knit neckband, cut the strip to about 85% of the neckline opening — the stretch lets it sit flat when applied. Ribbing stretches more, so cut to about 75%. For woven bias binding there is no stretch, so cut to 100% of the neckline plus about 2cm for the overlap/join.
The neckline drop is how far below the base of the neck the neckline sits at centre front. A standard round/crew neckline drops about 7–8cm. A scoop neck drops 10–12cm. A deep V can drop 12–20cm or more. The back of the neck stays a shallow ~2cm scoop on most styles.
A pull-on neckline with no opening fastening must stretch over the head. The accepted minimum finished opening is about (head circumference + neck circumference) ÷ 2 for a knit with roughly 50% stretch. This calculator floors the result at that minimum so the garment can actually go on.
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Last updated: June 2026
All calculations are estimates. Always verify quantities before cutting or purchasing fabric.