DAILY RATE

Measurement of the daily rate on a timing machine (+ 10.7 s/day)

The daily rate is the rate deviation of a timepiece over twenty-four hours, expressed in seconds per day and assigned a sign: a positive value indicates a watch that runs fast, a negative value a watch that runs slow. It is the main indicator of the accuracy of a mechanical movement. It is measured by comparing the watch’s time to a reliable reference, or more precisely using a timing machinewhich analyzes the sound of the escapement in different positions.

The daily rate of a given movement varies indeed according to position, amplitude, winding state, temperature and magnetism, which explains why chronometric tests are carried out under standardized conditions. To obtain chronometer certification, the average daily rate must remain within strict tolerances. The precise purpose of regulation / adjustment is to reduce and homogenize the daily rate. This value thus conveys, in a single meaningful figure, the quality of the regulation work and the health of a movement.

Useful links:

• Regulation / Adjustment
• The regulating organ
• The timing machine
• The correction of the daily rate
• The certification of chronometers (ISO 3159)