Accuracy
Quartz vs automatic: which keeps better time?
Quartz keeps far better time than automatic. A good quartz watch drifts roughly ±15–20 seconds per month, while a typical automatic (self-winding mechanical) watch drifts about ±5–20 seconds per day — quartz is one to two orders of magnitude more accurate.
The numbers
A quartz movement keeps time with a tiny tuning-fork crystal vibrating 32,768 times per second, divided down electronically. That electronic reference is inherently stable, so monthly drift is measured in seconds.
A mechanical movement times itself with a balance wheel oscillating at, commonly, 28,800 vibrations per hour (8 beats per second). It is affected by temperature, position, magnetism, and mainspring tension, so daily drift is measured in seconds per day, not per month.
Certified mechanical accuracy
Chronometer certification narrows the mechanical gap but never closes it. COSC certification requires an average −4 to +6 seconds per day; Rolex's Superlative Chronometer guarantees −2 to +2 sec/day; Omega's METAS Master Chronometer specifies 0 to +5 sec/day plus 15,000-gauss magnetic resistance.
Even the best mechanical watch, at ±2 sec/day, drifts more in a week than a basic quartz watch does in a month. Accuracy is simply not where mechanical watches compete.
So why buy mechanical?
People choose automatics for craftsmanship, heritage, the sweep of the seconds hand, and the fact that a well-made mechanical watch can run for generations with servicing — no battery, no electronics to fail. Quartz wins on accuracy, low maintenance, and price; mechanical wins on soul and longevity.
Frequently Asked Questions
How accurate is a quartz watch per year?
A standard quartz watch drifts roughly ±15–20 seconds per month, which works out to a few minutes per year. High-accuracy quartz (thermocompensated) can hold ±10 seconds per year.
Is a COSC chronometer more accurate than quartz?
No. A COSC chronometer is certified to −4/+6 seconds per day, whereas even ordinary quartz drifts only ±15–20 seconds per month. Quartz remains far more accurate than any standard mechanical chronometer.
Do automatic watches lose time when not worn?
Yes — an automatic winds from wrist motion, so when it sits unworn it winds down and stops once the power reserve (commonly 38–80 hours) runs out, then needs resetting. It does not lose accuracy, it simply stops.
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