Find the Right Watch Size for Your Wrist

The tool uses the widely-repeated proportional rule case_diameter_mm ≈ 22 + wrist_circumference_mm ÷ 4.7. That produces a center value around which ±2 mm marks a well-fitting range. The "Slim" preset shifts the center down by 2 mm.

Around 160–180 mm (roughly 6.3–7.1 inches) is the sweet spot for a 40 mm case — the modern mid-size standard for men and larger women. Smaller wrists 150–165 mm usually look best with 36–38 mm, and 185+ mm wrists can handle 42–44 mm.

For wearability — yes. A watch with long lugs can look oversized on a narrow wrist even if the case is small. Lug-to-lug should not exceed the flat top of your wrist (usually wrist circumference ÷ 2.5 ≈ 70 mm for a 175 mm wrist).

The classic rule is strap width = case diameter ÷ 2, so a 40 mm case pairs with a 20 mm strap. Straps are typically made in 2 mm increments (18, 20, 22 mm).

Yes — a flat, wide wrist can carry a larger case at the same circumference. The tool optimises for the average oval wrist; for very flat wrists you can safely go 1–2 mm larger, and for round/bony wrists 1–2 mm smaller.

Any flexible string or strip works — mark where it overlaps and measure the strip with a ruler. Avoid stiff tape that won't conform to the wrist curve. Expect ±2 mm error, well within the recommended range.