Use this horology calculation to interpret a stated watch, clock, timing-machine, water-resistance, alarm, or historical respiratory-timing quantity under its defined convention.

Lug To Lug Millimeters (mm)

Required number input.

Wrist Width Millimeters (mm)

Required number input.

Watch lug-to-lug span divided by wearer wrist width, using matching length units. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Ratio

The resulting ratio returned as a number.

• Mechanical-watch amplitude and beat measurements depend on lift angle, position, state of wind, movement condition, instrument setup, and elapsed sampling. ATM markings are test-pressure classifications rather than literal safe diving depths.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Confirm movement specifications and measure in multiple positions and power states; follow the manufacturer's water-resistance guidance and obtain pressure testing after case service.

• Wrist Coverage Percent

  Lug-to-lug watch span as a percentage of wearer wrist width.

• Gear Train Ratio

  Driven rotational speed divided by driving rotational speed for one meshing gear pair.

• Amplitude Lift Ratio

  Ratio of a movement's actual lift angle to the lift angle assumed in an amplitude calculation.