Necklace charts usually show one woman’s neck and one set of lengths, which is why an 18" chain arrives as a choker for one buyer and a princess length for another. This page lets you set your own neck size and fit and shows where every standard length falls, then draws chain widths at true size.
The standard lengths and their names
Retailers use broadly the same names: collar 12–14", choker 14–16", princess 17–19", matinee 20–24", opera 28–36" and rope beyond 36". Children’s necklaces are usually 12 to 16". The names describe where a chain sits on an average women’s neck of about 13 to 14 inches, not a fixed body position.
There is no published standard for men’s lengths. Men’s necks are usually 15 to 18 inches, so the same chain sits higher: an 18" chain that lies on a woman’s collarbone hugs the base of a 17" men’s neck. Most men choose 20 to 24 inches for a chain worn alone and 24 inches or longer with a pendant.
How the drape is worked out
A chain wraps the back of the neck and falls in two runs to its lowest point at the front. We model the neck as a circle of your measured circumference and solve for how far the point falls below the base of the throat. A chain the same length as your neck sits tight at the throat; every extra inch adds roughly half an inch of drop once the chain clears the neck.
Bodies differ, so the landmarks on the diagram are averages. The useful part is the comparison: on your neck, the 20" falls about an inch below the 18". A pendant adds its own height below the chain.
Chain length L = r(2π − 2θ) + 2√(D² − r²), r = neck ÷ 2π, θ = acos(r/D); drop = D − r
Measuring your neck
Wrap a soft tape or a paper strip round the base of your neck where a chain would sit, not round the middle, and read it without pulling tight. Use the slider to set it. For a chain that clears a shirt collar, choose a length that falls below the dashed neckline drawn for your collar style.
Chain width at true size
Chain width is measured across a single link. The 1:1 strip lets you see 1 to 12 mm before buying: 1 to 2 mm is fine and suits small pendants, 3 to 4 mm reads clearly on its own, and 5 mm and above is a statement chain. A rope or Franco chain looks heavier than a cable chain of the same width because it is fuller.