WR 100M / 10 Bar Marking — What This Mark Means
A water resistance rating of 100 meters (10 bar/ATM), generally considered suitable for swimming and recreational water activities. Not rated for scuba diving or high-impact water sports.
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A 100M rating indicates the watch was tested to 10 bar of static pressure and is the level generally considered adequate for pool swimming, snorkeling, and watersports on the surface. It has become the standard rating for everyday sports watches: pieces like the Rolex Datejust and Seiko 5 Sports line carry 100m, positioning them as swim-ready without being dive watches.
The distinction from a true diver matters. When Seiko replaced the SKX007, a 200m ISO-rated diver, with the similar-looking 5 Sports SRPD models, the rating dropped to 100m, and the new watches are marketed for swimming rather than scuba. Scuba diving conventionally calls for 200m and ideally ISO 6425 certification.
Where to Find It
The rating appears on the case back as "WATER RESIST 100M," "WR100," "10 BAR," "W.R. 10ATM," or "WATER RESISTANT 330FT." Sports models often repeat it on the dial, commonly as "100m" or "10 BAR" beneath the model name.
Some watches display both units together, such as "10 BAR / 100M."
Common Variations
The same rating appears as 100M, 10 BAR, 10 ATM, or 330 feet. Nearby ratings exist too: some brands use 120m or 150m (Omega's Aqua Terra line is 150m, for example), which sit in the same practical category of swim-safe but not dive-rated.
Crown type varies at this level. Many 100m watches use well-sealed push-pull crowns, while others add a screw-down crown for extra margin; both approaches can legitimately meet the rating.
Common Misconceptions
A 100m rating does not mean the watch is safe at 100 meters' depth, and it is not a dive rating: scuba requires at least 200m, ideally with ISO 6425 certification. The rating also assumes healthy gaskets, so an older, unserviced 100m watch may no longer deliver it.
Another common error is operating the crown or pushers in the water, which can bypass the seals on watches not specifically designed for underwater operation.
What to Do Next
A 100M watch can handle swimming and light watersports. Make sure the crown is fully pushed in (or screwed down, if applicable) before water contact, avoid operating it while wet, and rinse the watch with fresh water after any saltwater exposure.
If you swim with it regularly, have the gaskets pressure-tested about once a year, ideally before the swimming season.
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Related Markings
A marking indicating the watch's tested water resistance depth, typically shown in meters, feet, bar, or ATM. This ratin
WR 50M / 5 Bar MarkingA water resistance rating of 50 meters (5 bar/ATM), indicating the watch can handle everyday moisture like rain and hand
WR 200M / 20 Bar MarkingA water resistance rating of 200 meters (20 bar/ATM), suitable for serious water sports and recreational scuba diving. T
Commonly Seen On
Often Confused With
- WR 200M / 20 Bar Marking
200m watches tolerate high-impact water sports and recreational scuba; 100m stops at swimming and snorkeling.
- Bar / ATM Pressure Rating
10 bar / 10 ATM is the identical rating in pressure units rather than depth.
Related searches
Frequently asked questions
Can I swim with a 100M water resistant watch?
Yes. 100M is generally considered suitable for pool swimming, snorkeling, and recreational water activities.
Is 100M enough for scuba diving?
No. Scuba diving requires at least 200M water resistance and ideally ISO 6425 dive watch certification.
Should I avoid the shower with a 100M watch?
While it can technically handle it, hot water and soap can accelerate gasket degradation, so many watchmakers advise against it.
How often should I have the water resistance checked?
Annually is recommended if you regularly wear it around water, or at least every time you have the watch serviced.
Can I press the buttons underwater?
Only if the watch is specifically designed for it (like dive chronographs). On most watches, operating pushers underwater can allow water ingress.
Does saltwater affect water resistance?
Salt can corrode gaskets and seals over time. Always rinse with fresh water after saltwater exposure.
Does a 100M watch need a screw-down crown?
Not necessarily. Many 100m watches achieve the rating with well-sealed push-pull crowns, while others use screw-down crowns for additional security. What matters is that the crown is fully seated or screwed down before any water exposure.
Sources
- ISO 22810 — Horology: water-resistant watches