Watch Performance & Specs
A watch's spec sheet is really a list of how well it performs -- how deep it can go, how accurately it keeps time, how long it runs off a wind, and how well it resists water, magnetism, shocks and scratches. This hub explains every performance and specification term you will meet, grouped into three areas: resistance & protection, accuracy & certification, and power & legibility. It is the canonical home for power reserve; for water resistance we give the quick version and link out to the full guide.
Water resistance at a glance
| Rating | Depth | Safe for | Not for |
|---|---|---|---|
| 3 ATM | 30 metres | Rain, splashes, hand-washing | Swimming, showering |
| 5 ATM | 50 metres | A quick swim, light water sports | Diving, high-pressure jets |
| 10 ATM | 100 metres | Swimming, snorkelling, water sports | Scuba / deep diving |
| 20 ATM | 200 metres | Recreational diving, all water sports | Saturation / technical diving |
Ratings are static laboratory pressures (ISO 22810), not literal swim depths -- heat, soap and movement reduce them, so stay well inside the figure. Full detail: Water Resistance & ATM guide.
Resistance & protection
Water Resistance
How well a watch keeps water out, rated in metres or ATM (atmospheres). The figure is a laboratory pressure rating, not a literal diving depth -- see our dedicated guide for the full breakdown.
What it means
A water-resistance rating tells you how much static water pressure a watch's case, crystal and crown seals can hold out, expressed in metres or in ATM (1 ATM is roughly the pressure of 10 metres of water). It is measured under ISO 22810 in still laboratory conditions, so the metre figure is a pressure benchmark rather than the depth you can safely swim to.
The short version
30m / 3 ATM handles splashes and rain only; 50m / 5 ATM allows a quick swim; 100m / 10 ATM covers swimming and snorkelling; 200m / 20 ATM suits serious water sports and recreational diving. Heat, soap and sudden movement all add pressure, so always stay well inside the rating and never operate the crown underwater.
Read the full guide
Water resistance has its own depth-rating table, gasket-care advice and a plain-English chart on our dedicated page -- Water Resistance & ATM ratings explained. The quick compare table below sits within this hub for convenience.
Shock Resistance
A watch's ability to survive knocks and drops without losing accuracy. Mechanical movements use a sprung mounting for the balance staff; quartz watches are inherently more robust.
What it is
Shock resistance is how well a movement copes with sudden impacts -- a knock against a door frame or a drop onto a hard floor. The most vulnerable part of a mechanical watch is the thin balance staff that the balance wheel pivots on, which can snap under a sharp blow.
How it works
Mechanical movements use a sprung shock-protection system -- a spring-loaded jewel setting at each end of the balance staff that lets it move slightly under impact and spring back, absorbing the shock instead of breaking. The wider standard is the ISO 1413 shock test, which drops a watch to simulate a one-metre fall onto a hard floor. Quartz movements have no delicate balance staff and are naturally more shock-tolerant.
In plain terms
Quartz watches -- the bulk of our BOSS, Tommy Hilfiger, Olivia Burton, Vivienne Westwood and Swarovski ranges -- shrug off everyday knocks easily. A mechanical or automatic watch is well protected but should still be treated with a little more care, especially during sport.
Magnetic Resistance (Nivachron)
Magnetism is the hidden enemy of mechanical watches -- it makes them run fast. Modern anti-magnetic hairsprings such as Tissot's Nivachron strongly resist it; quartz is largely immune.
Why magnetism matters
Everyday items -- phone cases, speakers, laptops, magnetic clasps and fridge magnets -- carry magnetic fields. A traditional steel hairspring can become magnetised, causing its coils to stick together so the watch suddenly gains minutes a day. It is one of the most common reasons a mechanical watch starts running fast.
How modern watches resist it
The fix is a non-ferrous hairspring. Tissot's Powermatic 80 uses a Nivachron hairspring -- a titanium-based alloy developed by ETA that greatly reduces the effect of magnetic fields, as well as resisting temperature swings and shocks. It is rated to resist magnetism many times better than the older Nivarox steel-alloy springs it replaced. For reference, dive and tool watches from other makers sometimes add a soft-iron inner case (a Faraday cage) for further shielding -- not a feature of our current range.
Quartz and magnetism
Quartz movements are largely unaffected by magnetism -- a strong field can briefly disturb the stepper motor, but the watch returns to normal once away from the magnet. If your mechanical watch suddenly runs fast, magnetism is the likely cause and a quick demagnetising at a watchmaker usually cures it.
In our range
Our Swiss mechanical watches lead with Tissot's Powermatic 80 and its Nivachron hairspring. For the movement detail, see the Powermatic 80 guide and the wider movements hub.
Durability
The all-round toughness of a watch -- a product of case material, crystal, seals and movement. Titanium and hardened coatings push it furthest.
What it is
Durability is the sum of everything that keeps a watch working and looking good for years: a tough case material, a hard scratch-resistant crystal, well-seated gaskets for water resistance, and a robust movement. No single number captures it, but the choices in each area add up.
What drives it
Stainless steel (typically 316L) is the durable everyday baseline. Titanium is lighter and naturally hypoallergenic. Citizen's Super Titanium goes further -- its Duratect surface hardening makes it around five times harder than ordinary steel while staying about 40% lighter -- so it resists the everyday scratches that dull a steel case. A sapphire crystal protects the most-exposed surface of all.
In our range
For light-powered toughness, Citizen Eco-Drive models -- many in Super Titanium -- are built to run for the life of the watch with no battery to replace. Explore Citizen Eco-Drive and the wider Citizen range.
Scratch Resistance
How well the crystal and case shrug off everyday marks. Sapphire crystal -- 9 on the Mohs scale, second only to diamond -- is the gold standard.
What it is
Scratch resistance is mostly about the crystal -- the clear cover over the dial -- because that is the surface your watch knocks against most. It is measured by hardness on the Mohs scale, where talc is 1 and diamond is 10.
Sapphire vs mineral
Synthetic sapphire crystal sits at 9 on the Mohs scale, second only to diamond, so it resists scratches from keys, coins, desks and quartz dust that would mark softer glass. Mineral (hardened) glass is around 5 to 6 -- more scratch-prone but cheaper to replace. Sapphire is extremely hard but not unbreakable: a sharp impact on a hard edge can still chip it. For the full picture see our Sapphire Crystal guide.
Cases too
Case hardness matters as well -- this is where Citizen's Duratect-hardened Super Titanium earns its keep, resisting the desk-diving scuffs that dull a polished steel case. Tissot's sports models pair a steel or titanium case with a sapphire crystal.
In our range
Tissot and Citizen sports models use sapphire crystals -- see Tissot watches and Citizen watches.
Accuracy & certification
Accuracy (s/day, s/month, s/year)
How close a watch keeps to true time. The headline metric, and it varies hugely by movement type: mechanical is rated in seconds per day, quartz in seconds per month, the best quartz in seconds per year.
How accuracy is stated
Accuracy is quoted over a time window, and the window tells you the movement type at a glance. Mechanical watches are measured in seconds per day; standard quartz in seconds per month; and high-accuracy quartz in seconds per year. The longer the window, the more accurate the watch.
Typical figures
A good modern mechanical watch runs to roughly -15 to +15 seconds a day; a chronometer-grade one to -4/+6 s/day. Standard quartz holds about plus or minus 15 seconds a month -- far tighter than any mechanical. High-accuracy quartz reaches about plus or minus 5 to 10 seconds a year, and radio- or satellite-synced watches reset themselves to an atomic clock so they are effectively never wrong.
What affects it
Position, temperature, magnetism, shock and how fully wound a mechanical watch is all shift its rate. Quartz is mostly thrown only by temperature, which is exactly what high-accuracy quartz corrects for. For the why behind each movement's accuracy, see the movements hub and the Swiss Quartz guide.
COSC
The Swiss official body that tests and certifies chronometers. A COSC certificate means a mechanical movement passed 15 days of testing to a strict accuracy standard.
What it is
COSC -- the Controle Officiel Suisse des Chronometres -- is the independent Swiss institute that tests watch movements and awards chronometer certification. A movement that passes is a certified chronometer; one that does not, simply is not.
How the test works
Each mechanical movement is tested over 15 days, in five positions and at three temperatures (8, 23 and 38 degrees C), against seven criteria based on the ISO 3159 standard. The headline requirement is an average daily rate between -4 and +6 seconds per day -- much tighter than the -15/+15 of an ordinary mechanical watch.
Why it matters
A COSC certificate is independent proof that a specific movement keeps exceptional time, not just a maker's claim. It applies to the movement, so two watches with the same calibre may differ on whether they carry certification. COSC certifies some Tissot calibres; not every Tissot is chronometer-rated, so check the individual model.
Chronometer
A watch whose movement has passed an official precision test -- most often COSC. Not to be confused with a chronograph (a stopwatch complication).
What it is
A chronometer is a high-precision watch whose movement has passed an official timekeeping test and earned certification -- in Switzerland, almost always from COSC. The word is a protected term: a watch can only be called a chronometer if it holds a valid certificate.
Chronometer vs chronograph
These two are constantly confused. A chronometer is about accuracy -- a certified-precise movement. A chronograph is a function -- a built-in stopwatch with extra pushers and sub-dials. A watch can be one, both, or neither.
Beyond COSC
COSC is the common Swiss standard, but stricter ones exist -- for example METAS Master Chronometer testing, which adds anti-magnetic and real-wear criteria. Reference only -- our certified precision comes via COSC-grade Swiss movements from Tissot where specified.
Power & legibility
Power Reserve
How long a mechanical watch keeps running after it is fully wound and taken off the wrist. Standard automatics hold 38-50 hours; a Tissot Powermatic 80 holds a full 80 hours.
What it is
Power reserve is the running time stored in a fully wound mechanical watch -- how long it will keep ticking once you stop winding it or take it off your wrist. It is set by the size and design of the mainspring and barrel. Quartz and solar watches do not have a power reserve in this sense; they run continuously from a battery or stored light charge.
Why it matters in daily life
Power reserve decides what happens when a watch sits idle. A standard automatic holds roughly 38 to 50 hours, so take it off on Friday evening and it may have stopped by Sunday, needing a wind and a time reset. A long-reserve movement skips that nuisance -- leave it off all weekend and it is still running and accurate on Monday.
The 80-hour benchmark
Tissot's Powermatic 80 is named for its standout 80-hour power reserve -- more than three full days off the wrist -- achieved with a redesigned mainspring and an efficient escapement, and paired with a Nivachron anti-magnetic hairspring. It is the modern Swiss workhorse for set-and-forget mechanical ownership.
Power-reserve indicators
Some watches add a small dial or hand showing how much reserve is left, so you know when to wind. For the calibre detail see the Powermatic 80 guide; to shop it, browse Tissot Powermatic 80 and the wider Tissot range.
Luminescence (Super-LumiNova)
The glow that lets you read a watch in the dark. Modern lume -- Super-LumiNova -- charges from light and fades slowly; it is non-radioactive and safe.
What it is
Luminescence -- usually shortened to lume -- is the luminous coating on hands and markers that glows in the dark. The modern industry standard is Super-LumiNova, a photoluminescent pigment based on strontium aluminate.
How it works
Super-LumiNova is charged by light -- a few minutes under daylight or a lamp stores energy, which it then releases as a glow that is bright at first and fades gradually over the night. It contains no radioactive material, so it is completely safe and never wears out, though it needs re-charging from light. An older alternative, tritium gas tubes, glows continuously for years without charging by self-powered radioluminescence -- a feature of some specialist tool watches, not our range.
Why it matters
Good lume is about legibility -- glancing at the time in a dark room or at the cinema without reaching for a light. The quality and quantity of the pigment decide how bright and how long it glows. Many Tissot and Citizen sports models carry strong Super-LumiNova for exactly this reason.
AR Coating
An anti-reflective layer on the crystal that cuts glare so the dial stays readable in bright light. Often applied to the underside of a sapphire crystal.
What it is
AR (anti-reflective) coating is a microscopically thin optical layer applied to the watch crystal to reduce reflections. It is the same principle used on camera lenses and spectacles.
What it does
Without coating, a crystal mirrors the sky and lights, hiding the dial behind glare. AR coating lets more light pass through and bounces less back, so the dial reads cleanly even in bright sun. It is commonly applied to the inside face of a sapphire crystal -- protected there from wear -- and sometimes on both faces for maximum clarity.
Why it matters
Better legibility, and a crystal that almost disappears so you see the dial, not a reflection. It pairs naturally with sapphire crystals on quality sports and dress watches -- see our Sapphire Crystal guide.
Screw-Down Crown
A crown that screws tight against a gasket to seal the case -- the key to serious water resistance on sports and dive watches.
What it is
The crown is the winding and setting knob on the side of the case, and it is the biggest potential leak point because it has to turn and pull out. A screw-down crown threads down onto the case tube, compressing a gasket to seal it shut.
How it works
You unscrew the crown to wind or set the watch, then screw it back down until it seats against its O-ring seal. That sealed connection is what lets a watch reach the higher water-resistance ratings -- 100m / 10 ATM and above. A push-pull crown (no threads) is fine for everyday splash resistance but not for swimming or diving.
The golden rule
Never operate -- or leave unscrewed -- a screw-down crown in or near water. An open crown defeats the seal entirely, and water in the movement is the most common, and most expensive, watch fault. Always check it is screwed fully home before any contact with water.
In our range
Tissot and Citizen sports and dive models -- such as the Tissot Seastar and Citizen Promaster -- use screw-down crowns with sapphire crystals for genuine water resistance. Browse Citizen Promaster and Tissot watches.
Frequently asked questions
What does the power reserve of a watch mean?
Power reserve is how long a mechanical watch keeps running after it is fully wound and then taken off the wrist. Standard automatics hold roughly 38 to 50 hours; a Tissot Powermatic 80 holds a full 80 hours, so it is still running after a weekend in a drawer.
Which watch has the longest power reserve we stock?
Among our range, the Tissot Powermatic 80 leads with an 80-hour power reserve -- more than three days off the wrist -- thanks to a redesigned mainspring and an efficient escapement.
Is 5 ATM enough for swimming?
5 ATM (50 metres) is fine for a quick swim and everyday water contact, but it is not made for diving, high-pressure jets or long immersion. For regular swimming and water sports, 10 ATM (100 metres) is the safer choice.
What does 100m water resistance actually allow?
100m / 10 ATM covers swimming, snorkelling and water sports. It does not mean you can scuba dive to 100 metres -- the figure is a static laboratory pressure rating, and real-world movement and temperature reduce it. See our Water Resistance and ATM guide for the full table.
Can I shower with my watch on?
It is best not to. Hot water and soap degrade the gaskets that keep water out, and steam expands and contracts the seals. Even a 100m watch is better kept out of the shower to preserve its water resistance over time.
Why does my mechanical watch run fast?
The most common cause is magnetism. Phones, speakers, laptops and magnetic clasps can magnetise a steel hairspring so the coils stick and the watch gains time. A watchmaker can demagnetise it in seconds. Modern anti-magnetic hairsprings like Tissot's Nivachron strongly resist this.
What is a Nivachron hairspring?
Nivachron is a titanium-based hairspring alloy developed by ETA and used in Tissot's Powermatic 80. It greatly reduces the effect of magnetic fields -- many times more resistant than the older Nivarox steel alloy -- and also resists temperature changes and shocks.
What is COSC certification?
COSC is the official Swiss body that tests and certifies chronometers. A movement is tested over 15 days in five positions and three temperatures, and must keep an average daily rate of -4 to +6 seconds a day to earn certification.
What is the difference between a chronometer and a chronograph?
A chronometer is about accuracy -- a movement officially certified to keep very precise time (usually by COSC). A chronograph is a function -- a built-in stopwatch with extra pushers and sub-dials. A watch can be one, both, or neither.
How accurate is a quartz watch compared to mechanical?
Standard quartz keeps time to about plus or minus 15 seconds a month, far tighter than a mechanical watch's roughly -15 to +15 seconds a day. High-accuracy quartz reaches a few seconds a year.
Is sapphire crystal scratch-proof?
Almost. Sapphire crystal sits at 9 on the Mohs hardness scale, second only to diamond, so it resists scratches from keys, coins and quartz dust. It is not unbreakable, though -- a sharp knock on a hard edge can still chip it.
What is the difference between sapphire and mineral crystal?
Sapphire crystal is around 9 on the Mohs scale -- extremely scratch-resistant. Mineral (hardened) glass is roughly 5 to 6 -- it scratches more easily but is cheaper to replace. Most quality watches use sapphire on the dial side.
What does AR coating do?
AR (anti-reflective) coating is a thin optical layer on the crystal that cuts glare and reflections, so the dial stays readable in bright light. It is often applied to the underside of a sapphire crystal where it is protected from wear.
How does watch lume work?
Modern lume (Super-LumiNova) is a photoluminescent pigment that charges from light -- a few minutes under daylight or a lamp -- and then glows in the dark, fading gradually over the night. It is non-radioactive and never wears out, but needs recharging from light.
Why must I never use the crown underwater?
On a screw-down crown, an unscrewed crown breaks the seal entirely and lets water straight into the movement -- the most common and most expensive watch fault. Always make sure the crown is screwed fully home before any contact with water.
What is a screw-down crown?
A screw-down crown threads onto the case tube and compresses a gasket to seal the watch -- the key to serious water resistance of 100m / 10 ATM and above. You unscrew it to wind or set the watch, then screw it back down before going near water.
Are quartz watches affected by magnets?
Barely. A strong magnet can briefly disturb a quartz movement's stepper motor, but it returns to normal once away from the field. Magnetism is mainly a problem for mechanical watches with steel hairsprings.
How shock-resistant are watches?
Quartz watches are naturally robust as they have no delicate balance staff. Mechanical watches use a sprung shock-protection system that lets the balance staff move and spring back under impact, and are tested to standards like ISO 1413 (a simulated one-metre drop).
What is Super Titanium and is it tougher than steel?
Super Titanium is Citizen's Duratect surface-hardened titanium -- around five times harder than stainless steel and about 40% lighter, as well as hypoallergenic. It resists the everyday scratches that dull a polished steel case.
How often should water resistance be checked?
Water resistance is not permanent -- gaskets and seals degrade over time. If you swim with your watch, have it professionally pressure-tested every couple of years, and whenever the case has been opened for a battery or service.
Does a higher ATM rating mean a tougher watch overall?
Not directly. ATM measures only water resistance. Overall toughness also depends on the case material, crystal hardness and movement -- a 5 ATM titanium watch with a sapphire crystal may survive daily life better than a 10 ATM steel one with mineral glass.
What is the most accurate type of watch I can buy from you?
Our most accurate everyday watches are Citizen's high-accuracy quartz and Eco-Drive models, accurate to a few seconds a year on the top lines. For Swiss mechanical precision, Tissot's COSC-grade calibres offer chronometer-level accuracy of -4 to +6 seconds a day.