How do water resistance ratings work in watches?

Vaer Watches Updated by Vaer Watches

Water-resistance ratings in watches are a confusing subject because the depth rating numbers don't match real-world usage. In general, 10 ATM (100 meters depth rating) is the starting point for a watch being functionally waterproof.

Almost all men's wristwatches claim some level of water resistance rating on the case back - but what do these numbers actually mean? While 30 or 50 meters of water resistance may seem more than sufficient for a quick swim in the pool, in reality, they offer limited resistance beyond the occasional spray.

For a functionally waterproof watch (covering 99% of real-world use cases) you're going to need, at minimum, a watch rated to 100 meters (328ft) of water resistance - in the watch industry this rating is often abbreviated to 10 ATM (atmospheres) or 10 Bar.

Below is a quick summary of ATM ratings and what they mean:

  • 1 ATM - Essentially no water resistance, stay away.
  • 3 ATM - Covers splashes, not steam or submersion.
  • 5 ATM - Handles quick submersion and showering.
  • 10 ATM - Covers swimming and submersion.
  • 10 ATM + Lock Crown - Functionally waterproof.
  • 20 ATM - Waterproof to limits of the deep diving.
  • 30 ATM - Waterproof at depths of oxygen toxicity.
  • 100 ATM - Pretty much just showing off.   

"A watch with a 3ATM rating is usually an indication of poor build quality. Since those watches are inevitably going to flood, it means that the total cost of replacement is lower than the upgrade to 5ATM - which is typically only a few dollars."

- Reagan Cook, Vaer Co-Founder

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