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

Solar Hours (h)

Required number input.

Sidereal hours corresponding to a duration measured in mean-solar hours, using a sidereal day of 86164.0905 SI seconds. 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]

Sidereal Hours (sidereal-hour)

The resulting sidereal hours 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.

• Sidereal To Solar

  Mean-solar hours corresponding to a duration measured in sidereal hours, using a sidereal day of 86164.0905 SI seconds.

• Regulator Index Rate Change

  Predicted signed daily-rate change from index movement and measured sensitivity in seconds per day per index unit.

• Timing Rate Extrapolation

  Extrapolated seconds gained or lost per 24 hours from a measured signed error over an observation interval.