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.
What This Usually Means
A 100M rating indicates the watch was tested to 10 bar of static pressure. This level is commonly considered adequate for pool swimming, snorkeling, and recreational water exposure. However, it does not meet the requirements for scuba diving, which typically demands 200M or ISO 6425 certification.
Where to Find It
On the case back as "WATER RESIST 100M," "WR100," "10 BAR," "W.R. 10ATM," or "WATER RESISTANT 330FT."
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Common Variations
Appears as 100M, 10 BAR, 10 ATM, or 330 feet. Some watches display a combination, like "10 BAR / 100M." The specific wording and placement depend on the manufacturer.
Common Misconceptions
While 100M is suitable for recreational swimming, some people interpret it as safe for diving to 100 meters. It's not. Scuba diving requires at least 200M with ISO 6425 dive watch certification. Also, water resistance diminishes with age if gaskets aren't maintained.
What to Do Next
A 100M-rated watch can handle swimming and light water sports. Have gaskets inspected before the swimming season, especially on older watches. Avoid operating the crown while wet, and rinse the watch with fresh water after saltwater exposure.
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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
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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.