Tennis Necklace Lengths: Why 16 in Rules NYC but 40 cm Looks Right in Paris

Intro: The debate between a 16-inch tennis necklace in New York and a 40 cm version in Paris is mostly about units, bodies, and style — not fashion mysticism. A 16 in necklace is 40.64 cm; 40 cm is 15.75 in. That 6–7 mm gap can matter on the neck, but so do neck circumference, chain type, stone size, and local styling preferences. This article explains why both “rules” coexist, how to choose the right length, and how small differences affect where a tennis necklace actually sits.

The simple math — and why it matters: Jewelry in the U.S. is usually quoted in inches; Europe uses metric. Converting is straightforward, but conversion alone doesn’t guarantee the same look. A 16 in necklace equals 40.64 cm; a 40 cm necklace is about 15.75 in. The difference is roughly 6.4 mm. On a curved area like the neck, 6.4 mm can move the lowest point of a necklace several millimeters, which is visible against the collarbone.

How necklace length relates to fit: Necklace length is measured end-to-end around the necklace when it’s closed. Your neck measurement is the circumference of your neck. The extra length (necklace length minus neck circumference) determines how much “sag” or drop you get. A useful rule-of-thumb: the vertical drop at the front is approximately half of that extra length.

Example: if your neck is 35 cm and you wear a 40 cm necklace, the extra 5 cm produces roughly a 2.5 cm drop from the base of the neck to the center front. That places the piece near the collarbone. Smaller extra lengths (1–2 cm) keep a necklace high and choker-like; larger differences (10+ cm) produce a long drop to mid-chest.

Why NYC often lists 16 in as “standard”: In many U.S. listings and retail practices, 16 in is treated as a standard for delicate styles and for sizing references. Jewelry buyers and sellers are used to inch-based measurements, and 16 in often hits the base of the neck or collarbone on many women. Retail models in NYC fashion shoots may have neck circumferences that make 16 in look ideal. For consistent inventory and return policies, stores use a single common size as a rule.

Why 40 cm “looks right” in Paris: European jewelers and clients use metric. French design aesthetics often favor slightly closer-to-neck lengths and a minimalist silhouette, so 40 cm is a common quoted length. Practically, 40 cm sits nearly the same as 16 in on many necks (difference is small). Parisian wardrobe choices — high necklines, fine fabrics, and an emphasis on collarbones — also influence what lengths are preferred. The result is convergence: different units, similar visual intent.

How chain and stone characteristics change perceived length:

• Chain flexibility: A flexible box or cable chain drapes and creates a smooth semicircle. Stiffer chains or heavy graduated settings don’t conform as closely, so the lowest point can sit higher or skew to one side.
• Stone size and spacing: Tennis necklaces use many stones. Larger stones (4 mm rounds ≈ 0.25 ct each) add mass and stiffness. A necklace made of 1.8–2.5 mm stones (≈0.03–0.06 ct each) will lie softer and may feel slightly longer because it molds better to the neck curve.
• Metal and setting weight: A heavier platinum setting or thicker prongs pulls the necklace down a bit more than a lighter micro-prong gold setting. That effect is subtle but worth noting for long continuous-stone pieces totaling 10+ carats.

Practical length guide (how things usually sit):

• 14 in / 35 cm: Choker on most necks. Sits high and close to throat. Good for small necks or a dramatic collarbone look.
• 16 in / 40.6 cm (or 40 cm): Sits at the base of the neck or directly on the collarbone for many people. This is the “classic” tennis-necklace placement.
• 18 in / 45.7 cm: Falls below collarbone on most. Works well with V-necks and provides a cleaner separation between layers.
• 20–22 in / 50–56 cm: Mid-chest lengths. Better for larger necks or to avoid crowding multiple shorter pieces.

How to pick the right length — step-by-step:

• Measure your neck circumference with a soft tape where you want the necklace to sit. Note the number in cm and inches.
• Decide the location you want: base of neck (add ~5 cm), collarbone (add ~5–7 cm), below collarbone (add ~10 cm). Use the half-extra rule for approximate drop.
• Consider stone size and chain type. For heavy, large-stone tennis necklaces, choose a slightly longer length to compensate for the stiffer fall.
• If unsure, ask the seller for photos of the necklace on a neck similar to yours, or request a removable 2–4 cm extender. Extenders are inexpensive and give flexibility across wardrobes.

Specific examples: A 40 cm necklace on a 34 cm neck produces an extra 6 cm — drop ≈ 3 cm — good for showing the collarbone. On a 38 cm neck, that same 40 cm necklace leaves only ~2 cm extra — drop ≈ 1 cm — and will sit almost like a choker. These differences explain why a single labeled length won’t look identical on everyone.

Final practical notes: Whether you’re shopping in New York or Paris, convert units but focus more on your neck measurement, desired drop, stone sizes, and chain flexibility. A 16 in and a 40 cm necklace are almost the same, but small differences plus body shape and setting type change the outcome. When buying, measure, request pictures on a similar neck, and prefer removable extenders when in doubt — they solve the “16 vs 40” dispute more reliably than any city rule.