What the metre figure on the dial really describes
If a watch says 50 m or 5 bar, a testing device at the factory has subjected the case to an overpressure equivalent to a water column of 50 metres without water getting in. That is a statement about the tightness of the construction under static pressure. It is not a clearance to dive 50 metres deep with this watch.
The difference sounds pedantic, but it decides whether you get water damage. In the testing device the watch lies still, at constant temperature, with a firmly tightened crown and fresh gaskets. On the wrist, none of these four conditions reliably applies.
That is why every metre figure includes a deliberate safety margin. In practice, roughly one level below what the number suggests is permitted.
Bar, ATM and metres: one rating in three units
Three notations circulate side by side, and all three mean the same thing. 1 bar corresponds to the pressure of a water column of around 10 metres, and 1 ATM (atmosphere) is used synonymously with 1 bar. A watch with 10 bar, 10 ATM or 100 metres therefore carries the same rating, just written differently.
In practice that means: 3 bar is 30 metres, 5 bar is 50 metres, 10 bar is 100 metres, 20 bar is 200 metres. Some manufacturers print the metre figure, others the bar figure, many both. In our data sheets it is given uniformly in metres, so that models can be compared directly.
A linguistic subtlety as well: water-resistant is tied to a tested rating, whereas waterproof and splash-proof are vague advertising terms without a fixed meaning. If there is no rating at all, assume the worst case.
Why the metre figure is not the permitted diving depth
The core of the misunderstanding lies in the difference between static and dynamic pressure. The factory test works statically: water or air stand still, and the watch does not move. A watch on the wrist never behaves like that.
As soon as you move in the water, brief pressure peaks arise above the static pressure at the same depth. A stroke while swimming front crawl, a jump from the edge of the pool or the jet from a shower head press locally against the gaskets, crown and crystal. One metre of water depth at rest is harmless, but the same watch during a starting jump sees many times that.
Then there is direction: water hitting a crown gasket from the side finds a way in more easily than even pressure from all sides. This leads to the key message: the metre figure is a load-bearing class, not a depth rating.
ISO 22810, ISO 6425 and DIN 8310: the standards behind it
The general standard for water-resistant watches
ISO 22810 is the international standard for the conditions under which a watch may be called water resistant and marked with a metre rating. It describes the test procedures and the permitted labelling. In Germany, DIN 8310 defines the same term and historically forms the basis of many manufacturer specifications.
ISO 6425: the additional hurdle for genuine dive watches
Dive watches are subject to their own, much stricter framework in ISO 6425. Besides water tightness, it requires, among other things, a device for measuring dive time, usually the unidirectional rotating bezel, good legibility in the dark and resistance to salt water. Only watches that meet this framework may carry the marking DIVER'S.
In the catalogue, some manufacturers state this explicitly: the Certina DS Super PH500M with 500 metres at a guide price of €860, the Certina DS Action Diver with 300 metres at €700, the Citizen Promaster Automatic Diver NY0040 with 200 metres at €229. More are shown in the best dive watches, the best Certina watches and the best Citizen watches.
Water resistance in watches in practice: the scale from 30 to 300 metres
The following overview translates the ratings into everyday situations. It follows the conservative reading customary in the industry: a level is only approved when enough reserve remains for pressure peaks. The classification applies to an intact watch with the crown closed.
| Rating | Rain, hand washing | Showering | Swimming | Snorkelling | Scuba diving |
|---|---|---|---|---|---|
| 30 m / 3 bar | yes | no | no | no | no |
| 50 m / 5 bar | yes | brief, cold | no | no | no |
| 100 m / 10 bar | yes | yes | yes | yes | no |
| 200 m / 20 bar | yes | yes | yes | yes | yes |
| from 300 m / 30 bar | yes | yes | yes | yes | yes, with reserve |
For most people, the decision ends at 100 metres. This class covers rain, showers, the indoor pool and a day at the seaside without a second thought. Only those who dive with a tank and regulator need the 200 m class, ideally to ISO 6425.
Two levels deserve a warning. 30 metres is a dry class: rain and hand washing, nothing else. And 50 metres sounds like double the safety, but in practice only allows a brief, cold shower.
What the catalogue reveals about water resistance
The ratings of all 303 models show how the classes are distributed across watch types. The most common is 100 metres with 87 models, then 30 metres with 61 and 200 metres with 60. 50 metres is reached by 56 watches, 300 metres by 24.
| Watch type | Models | Most common value | Range |
|---|---|---|---|
| Dress watch | 101 | 30 m (48 models) | 30 to 100 m |
| Diver's watch | 65 | 200 m (36 models) | 100 to 1,200 m |
| Sports watch | 41 | 100 m (22 models) | 30 to 1,000 m |
| Field watch | 31 | 100 m (16 models) | 30 to 200 m |
| Chronograph | 28 | 100 m (20 models) | 30 to 300 m |
| GMT | 19 | 100 m (9 models) | 30 to 300 m |
| Digital watch | 18 | 200 m (8 models) | 30 to 200 m |
The dress watch stays dry
Of the 101 dress watches in the catalogue, not a single one exceeds 100 metres, and almost half are at 30 metres. This is not an oversight but a matter of construction: flat cases, push-in crowns and thin case backs cannot be sealed indefinitely without losing elegance. If you are looking for a watch to wear with a suit, it is therefore better not to make the metre rating an exclusion criterion.
30 metres says nothing about the price
The strongest evidence is right at the top of the price list: the Breitling Navitimer B01 Chronograph 43 costs a guide price of €9,300 and is rated at 30 metres, as are the IWC Portugieser Automatic 40 at €8,700 and the Cartier Ballon Bleu 40 at €7,000. At the other end, the Casio F-91W at €25 carries the same rating. At 50 metres are the Omega Speedmaster Moonwatch Professional at €7,600 and the Hamilton Khaki Field Mechanical at €600, see best chronographs and best field watches.
High water resistance comes cheap
Conversely, the 200 m class is no longer a luxury feature. The cheapest model with 200 metres is the Casio G-Shock DW-5600E at a guide price of €70, followed by the Casio Duro MDV-106 at €79 and the Casio G-Shock GA-2100 at €100. With an automatic movement, the Orient Mako II reaches the same value for €250, and the Orient Kamasu costs €300. Anyone who prefers not to wind anything at all will find a low-maintenance alternative in the solar-powered Citizen Promaster Diver BN0150, also at €250, with more in the best solar watches. Context: best Casio watches, best digital watches, best Orient watches, watches under €100.
The top of the scale
From 300 metres, professional territory begins, and the entry point is cheaper than you might expect: the Steinhart Ocean 39 at €450 and the Tissot Seastar 1000 Quarz 36 at €475 reach the class in which the Omega Seamaster Diver 300M at €6,000 also plays. Beyond that, only specialists will do: Steinhart Ocean One Titanium 500 Premium (500 metres, €720), Sinn EZM 3 (500 metres, €1,790), Squale Matic 60 Atmos (600 metres, €1,349), Mühle Glashütte S.A.R. Rescue-Timer and Sinn U1 with 1,000 metres each. The top of the catalogue is held by the Doxa SUB 300T Professional with 1,200 metres.
Screw-down crown, case back and crystal: what water resistance depends on
High metre ratings come not from thicker walls but from the number and quality of the sealed openings. Three places decide: crown, case back and crystal. Each of them is a joint that needs a gasket.
The crown is the most critical point because it is movable and the most frequently used. A screw-down crown tightens via a thread firmly against its gasket and is practically a prerequisite for anything from 100 metres. In the catalogue, the Nomos Glashütte Ahoi with 200 metres and the Longines Conquest 41 with 100 metres, for example, have this feature, with more in the best sports watches.
For the case back, the construction type decides: a press-fit back is cheaper, a screw-down one withstands higher pressure. For the crystal, the material matters less than thickness and secure seating, because a cracked crystal costs you water resistance immediately, whether sapphire or mineral. The remaining differences are explained in our comparison Sapphire crystal vs. mineral crystal. On chronographs, the pushers add two movable openings, which some manufacturers additionally screw down.
What endangers water resistance in everyday use
Most water damage does not occur because a watch went too deep, but because one of a few typical mistakes happened. These five points cover the majority.
- Crown not screwed down: After setting the time, it is easily left slightly open. Without a tightened crown, even a 300-metre watch is effectively unprotected.
- Operating pushers under water: Every press briefly opens a gap, on chronographs as on digital watches.
- Temperature changes: Sauna, whirlpool and hot showers make metal and gaskets behave differently. Condensation under the crystal is the result.
- Soap, shampoo and chlorine: Surfactants reduce surface tension, and chlorine attacks gaskets.
- Salt water without rinsing: Drying salt crystallises in threads and gasket grooves. After the sea, clear fresh water helps.
The rating is not a permanent state
A tested metre rating describes the condition at the time of the factory test, not forever. Gaskets made of plastic or rubber harden and become brittle over the years, regardless of whether the watch was ever in water. If you swim regularly, have the water tightness test carried out annually by a watchmaker. It is mandatory after every opening of the case, that is, after a battery change and a service.
Conclusion: which rating is enough for which everyday life
For a watch that only goes to the office and out for dinner, 30 or 50 metres is enough, and the expensive classics in exactly this class show that nobody has made a bad purchase because of it. If you wear it daily and do not want to take it off in the shower, set 100 metres as the lower limit. For regular swimming in the sea or scuba diving, there is no way around 200 metres and a screw-down crown, ideally to ISO 6425.
The most important rule remains the simplest: the number on the dial is a load-bearing class from a pressure test, not a promise for a dive depth. Treat it as a rough guide, keep the crown closed and keep an eye on the gaskets. Which type suits your everyday life is answered by the Watch Finder; all models are in the watch catalogue, terms are explained in Watch Knowledge, and further basics in the guides overview.