Daily Rate
The amount of time a watch gains or loses over 24 hours, usually expressed in seconds per day.
Also known as: rate per day, seconds per day, daily accuracy, daily deviation
Definition
Daily rate is the amount by which a watch gains or loses over 24 hours compared with a reference time. A watch running +5 seconds per day is gaining approximately five seconds every 24 hours under the conditions measured; -5 seconds means it is losing time. Mechanical rate can vary with position, state of wind, temperature and wear, so a multi-day average often tells more than one isolated reading. Timing machines measure instantaneous rates in controlled positions, while wrist results reflect actual use.
Why it matters
Daily rate gives owners a simple way to track timekeeping performance and spot changes. Persistent or worsening deviations can indicate a need for regulation, demagnetisation or service.