Answer
How accurate is a quartz watch?
Short answer
An ordinary quartz watch keeps time to about plus or minus 15 seconds a month, roughly half a second a day, which is around 20 times better than a certified mechanical chronometer. Thermocompensated quartz movements measure their own temperature and correct for it, and are specified at roughly plus or minus 10 seconds a year.
On this page (6 sections)
A conventional quartz watch is specified at around plus or minus 15 seconds a month, which is roughly half a second a day. That is about 20 times tighter than a Swiss chronometer certified to minus 4 to plus 6 seconds a day, and it is achieved by a movement that can cost a few dollars.
Above that sits a smaller category, thermocompensated or high accuracy quartz, specified in seconds per year rather than per month, typically around plus or minus 10 seconds a year and in the best cases around 5.
The numbers, side by side
| Type | Typical specification | Equivalent per day |
|---|---|---|
| Standard quartz | plus or minus 15 seconds a month | about 0.5 seconds |
| Thermocompensated quartz | plus or minus 10 seconds a year | about 0.03 seconds |
| COSC quartz chronometer | well under a tenth of a second a day | a few hundredths of a second |
| COSC mechanical chronometer | minus 4 to plus 6 seconds a day | minus 4 to plus 6 seconds |
| Typical non-certified automatic | roughly minus 10 to plus 20 seconds a day | same |
Put plainly: the least impressive quartz watch on a supermarket shelf outperforms the most impressive mechanical watch ever made, by a wide margin. People buy mechanical watches for other reasons, which our quartz versus mechanical guide sets out.
Why quartz is so much better
Inside the movement is a tiny bar of synthetic quartz, cut in the shape of a tuning fork and sealed in a metal can. Apply a voltage and it flexes; flex it and it generates a voltage. That piezoelectric behavior lets a simple circuit keep it vibrating at its natural frequency, which is chosen as 32,768 Hz, or 2 to the fifteenth power. Fifteen successive halvings in a divider chain turn that into one clean pulse per second.
Two advantages follow. The frequency is roughly 8,000 times higher than the 4 Hz of a common mechanical balance, so each tick is divided far more finely, and the resonator is a sealed, sub-milligram piece of quartz that gravity, friction and lubrication do not touch. A mechanical balance is fighting all three every second of its life.
Temperature is the limiting factor
What quartz is not immune to is heat. The frequency of a tuning fork crystal follows a shallow parabola: it is at its maximum near a turnover point around 25 degrees Celsius (77 Fahrenheit) and falls away as the temperature moves in either direction, which means the watch runs slow whether it gets hotter or colder.
The effect is roughly proportional to the square of the difference from that turnover point. Wearing a watch against skin at about 34 degrees Celsius (93 Fahrenheit) puts it some 9 degrees Celsius (16 Fahrenheit) off the peak, enough to cost a few seconds a month on its own. Leave the same watch in a cold car overnight and it loses more.
What thermocompensation actually does
A thermocompensated movement adds a temperature sensor and a lookup correction. The circuit measures its own temperature at intervals, typically every minute or so, works out how far the crystal has drifted from nominal, and adds or removes pulses from the divided output to cancel the error. Nothing about the crystal itself is better; the electronics simply know what the crystal is doing wrong and subtract it.
That single change moves the specification from seconds a month to seconds a year. It costs battery life, adds circuitry, and requires each movement to be calibrated individually, which is why it appears in a minority of watches and is stated prominently on the dial or the spec sheet when it does.
What else moves a quartz rate
- Battery voltage. Very little, until end of life. Most movements then jump the seconds hand in two or four second steps as a warning rather than drifting quietly.
- Crystal aging. A small frequency drift, largest in the first year or two, and small compared with temperature.
- Magnetism. Quartz timekeeping is unaffected by ordinary fields, though a strong field can disturb the stepper motor and stall the hands temporarily.
- Shock. A hard impact can crack a crystal or its mounting, which shows up as an abrupt and permanent change in rate.
Testing your own quartz watch
The seven-day wrist test used for mechanical watches is too short here: a watch rated at 15 seconds a month will drift about 3 seconds in a week, which is close to your own reading error. Set the watch precisely against an internet-synced clock, then leave it 30 days and read the deviation. That single figure, divided by 30 and multiplied out, is a usable monthly rate, and the accuracy calculator will do the conversion.
For a thermocompensated watch, budget a year. There is no shortcut at home: separating a 10 second per year specification from measurement noise takes either a long wait or laboratory equipment. If a quartz watch is out by minutes rather than seconds over a month, the problem is not rate. It is a failing movement, a mechanical obstruction on the hands, or a watch that was never set accurately in the first place.
Common follow-up questions
Does a dying battery make a quartz watch lose time?
Generally no. The circuit regulates its own timing and keeps correct time until the voltage falls too far, at which point most watches signal end of life by jumping the seconds hand in two or four second steps rather than drifting. If a quartz watch is genuinely running slow rather than skipping, suspect the movement or a mechanical drag on the hands, not the cell.
Is a more expensive quartz watch more accurate?
Only if it says so on the specification. Most quartz watches at any price use conventional untuned movements rated around 15 seconds a month. The accuracy jump comes from a specific technology, thermocompensation, which manufacturers advertise loudly because it costs more. A watch costing around $30 and one costing around $3,000 can share the same rating.
Are radio-controlled and GPS watches quartz?
Yes. They keep time with an ordinary quartz oscillator and then correct themselves against an external time signal, from a longwave radio transmitter, a GPS satellite or a paired phone. Between syncs they drift at the rate of the quartz movement inside, so their accuracy is really a statement about how often they can hear the signal.
Do quartz watches get less accurate with age?
Slowly. Quartz crystals age, with the frequency drifting a small amount in the first year or two and less thereafter, and the effect is a fraction of what temperature does. A quartz watch that suddenly gains or loses far more than its rating has usually been shocked, exposed to a strong magnetic field, or has a failing circuit.
Sources and further reading
- ISO 10553, Horology: procedure for evaluating the accuracy of quartz watches, for the standard method of stating quartz rate.
- Contrôle Officiel Suisse des Chronomètres (COSC), published criteria for quartz chronometer certification, which are tested at several temperatures.
- Manufacturer caliber documentation for thermocompensated quartz movements, which publish annual rate specifications and operating temperature ranges.
- Witschi Electronic, quartz measurement documentation, for gate times, rate measurement in parts per million and battery end-of-life detection.
- ISO 764, Horology: magnetic resistant watches, for the exposure threshold used in magnetic resistance testing.
Last reviewed 4 September 2026. Spotted an error? Tell us and we will fix it in public.