Quartz versus mechanical: an honest comparison

If you want the most accurate watch for the least money, buy quartz. If you want an object that can be repaired for a century and rewards knowing how it works, buy mechanical. Almost everything else written on this subject is decoration around those two sentences.

What follows is the technical basis for them, because the interesting question is not which is better but exactly where each wins, and by how much.

How a quartz watch works

Quartz is piezoelectric: squeeze it and it produces a voltage, apply a voltage and it deforms. Cut a sliver of synthetic quartz into a tiny tuning fork, seal it in an evacuated can and drive it with an oscillator circuit, and it vibrates at a frequency set almost entirely by its dimensions.

The industry standard frequency is 32,768 Hz, chosen because it is 2 to the power of 15. Dividing it down is then trivial: a chain of fifteen binary divider stages, each halving the frequency, turns 32,768 pulses per second into exactly one pulse per second. No awkward arithmetic, minimal circuitry, minimal current draw.

That one-per-second pulse drives a stepper motor, usually a Lavet-type design, in which a coil pulse of alternating polarity flips a small permanent-magnet rotor half a turn. The rotor drives the hands through an ordinary gear train. This is why an analogue quartz second hand steps rather than sweeps: it is kicked forward once per pulse. A "sweep" quartz watch simply uses a higher pulse rate to split each second into smaller steps.

Set against the chain of mainspring, gear train and escapement, a quartz movement is startlingly simple: a battery, a crystal, an integrated circuit, a coil, a rotor and a few wheels.

December 1969, and what it did to Switzerland

Seiko launched the Quartz Astron in Tokyo on December 25, 1969, the first commercially sold quartz wristwatch. It used an 8,192 Hz crystal rather than the 32,768 Hz that later became standard, a gold case, and a price comparable with a family car. Seiko quoted accuracy near 0.2 seconds a day, roughly five seconds a month, better than any mechanical wristwatch had managed.

The Swiss were not asleep. The Center Electronique Horloger in Neuchâtel, a consortium research body, had quartz prototypes under observatory test in 1967 and put its Beta 21 movement into member brands' watches in 1970. What the industry lacked was not the technology but the will to abandon a mechanical supply chain that employed most of a region.

What followed is remembered as the quartz crisis, and the commonly cited figures are stark: Swiss watch industry employment fell from roughly 90,000 at the start of the 1970s to around a third of that by the mid-1980s, with firm numbers falling by a similar proportion. Mechanical watchmaking survived by repositioning itself as a luxury and craft product, which is where it remains. The restructuring and the counter-movement that followed are traced in our history of the wristwatch.

The accuracy numbers

There are three tiers of quartz and they are separated by more than an order of magnitude.

Ordinary quartz is typically specified within about 15 seconds a month, and many movements beat their specification. The rate is not random drift: an untreated crystal has a fixed error, so a given watch reliably gains or loses at roughly the same rate.

Thermocompensated quartz, sold under names such as high accuracy quartz, is typically specified within about 5 to 10 seconds a year. Grand Seiko's 9F family and the high-accuracy calibers from Citizen and Longines sit in this band.

COSC-certified quartz exists and is separate from the mechanical chronometer test. The criterion is a mean daily rate within 0.07 seconds a day at 23 degrees Celsius, roughly 25 seconds a year, with further limits on how far the rate may move across a specified temperature range. Note the awkward implication: some uncertified high-accuracy quartz is specified tighter than the certified standard. The mechanical equivalents are covered in our guide to accuracy and chronometer standards.

Why temperature is the whole problem

A quartz tuning fork's frequency against temperature follows a parabola. It peaks at a turnover temperature near 25 degrees Celsius, conveniently close to wrist temperature, and falls away on both sides, with a coefficient generally quoted at around 0.035 parts per million per degree squared. Being a squared term, small deviations barely matter and large ones matter a great deal: a watch left on a cold windowsill or a hot dashboard loses far more than one on a wrist.

Thermocompensation measures the movement's own temperature with a thermistor and corrects for it, normally by inhibition: the circuit skips or adds a few pulses over a long counting window, following a curve calibrated for that individual crystal. Nothing mechanical changes. It is arithmetic applied to a known error, and it is why a thermocompensated watch is roughly twenty times more accurate for a modest increase in component cost.

Batteries, solar and kinetic

An ordinary quartz watch runs two to five years on a silver oxide cell, longer for low-drain movements. The cell is small and its metals recoverable, but a battery every three years across a lifetime is still a dozen or more cells, which is a fair point against quartz.

Two hybrids answer it. Solar quartz, of which Citizen's Eco-Drive is the best known, puts a photovoltaic cell behind a translucent dial and stores charge in a rechargeable cell, typically good for months in darkness. Kinetic movements, introduced by Seiko at the end of the 1980s, replace the battery with a rotor driving a miniature generator that charges a capacitor. Both remove routine battery changes; both eventually need their storage cell replaced, which is a service job rather than a counter one.

Spring Drive: a genuine third category

Seiko's Spring Drive is not a hybrid in the usual sense and earns its own column below. It is powered by a conventional mainspring and gear train, exactly like a mechanical watch, and can be automatic or hand-wound. What it does not have is an escapement.

Instead, the last wheel in the train, the glide wheel, spins freely. A coil and magnet arrangement around it generates a small current, which powers an integrated circuit and a quartz oscillator, and that circuit applies an electromagnetic brake to hold the glide wheel at exactly eight rotations per second. Seiko calls this combination of mechanical drive, electrical generation and electronic regulation the Tri-synchro Regulator. It was developed from the late 1970s and reached production in 1999.

Two consequences follow. The seconds hand glides with no steps at all, because nothing locks and releases. And accuracy is published by Seiko as about one second a day, or 15 seconds a month; the monthly figure is tighter than thirty times the daily one because day-to-day deviations partly cancel. That is far better than a mechanical chronometer and well short of thermocompensated quartz, because the reference crystal here is not temperature compensated.

The comparison

Servicing and the discontinued-module problem

This is the single most under-discussed difference, and it runs the opposite way to the usual snobbery.

Most inexpensive quartz movements are not repaired. They are replaced as a sealed module, because diagnosing a coil or an integrated circuit costs more in labor than a new movement costs to buy. That works beautifully until the module is discontinued. Integrated circuits are made in finite runs, and a fifteen-year-old quartz chronograph whose module is out of production may be genuinely unrepairable even though its case and dial are perfect. Owners of certain 1970s and 1980s electronic watches already live with this.

A mechanical watch has no such cliff edge. Every part is a mechanical component that a competent watchmaker can source, adapt or, at a price, make, and movements from the 19th century are routinely returned to service. This is the strongest practical argument for mechanical ownership, and it is about permanence rather than accuracy. Our guide to servicing and care covers what that upkeep involves.

The exception proves the rule. High-end quartz such as Grand Seiko's 9F was designed to be serviced, with a sealed and lubricated gear train and long-term parts support, and behaves much more like a mechanical watch in ownership terms.

A verdict without sneering

Quartz is the better instrument. It is more accurate, more robust, thinner, cheaper, and indifferent to magnetic fields and to being left in a drawer. Dismissing it as soulless is a marketing position invented by an industry that lost to it and rebranded the loss as a virtue.

Mechanical watches are not bought as instruments, and once you accept that, the comparison stops being uncomfortable. They are bought because a machine running on a coiled spring is an interesting thing to own, because it can be maintained indefinitely, and because watching a balance wheel through a caseback is a pleasure a battery cannot supply. Those are legitimate reasons. "It keeps better time" is not one of them, and anyone starting out should read our guide to buying your first mechanical watch with that in mind.