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

Driver 1 Teeth

Required integer input.

Driven 1 Teeth

Required integer input.

Driver 2 Teeth

Required integer input.

Driven 2 Teeth

Required integer input.

Rotational speed ratio across two motion-works gear stages from tooth counts. 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]

Speed Ratio

The resulting speed 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.

• Center To Escape Ratio

  Rotational speed ratio across two gear stages from driving and driven tooth counts.

• Gear Train Ratio

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

• Moonphase Gear Ratio

  Display-cycle days from moon-disc tooth count and tooth advances per day.