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

Error Ppm (ppm)

Required number input.

Days In Month (day)

Required integer input.

Signed accumulated timing error in seconds over a month with a supplied number of days. 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]

Drift Seconds (s)

The resulting drift seconds 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.

• Daily Rate To Annual Drift

  Signed clock drift over a supplied year length in days from seconds gained or lost per day.

• Daily Rate To Monthly Drift

  Signed clock drift over a specified number of calendar days from seconds gained or lost per day.

• Timing Rate Extrapolation

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