What Does ATM On The Back Of A Watch Mean?

What does ATM on the back of a watch actually mean?

If you turn your watch over, you will probably see a number then the letters ATM engraved on it.

What does this mean?

ATM on the back of a watch stands for ATMOSPHERES.

Which is a little odd.

1ATM (or 1 ATMOSPHERE) is the normal atmospheric pressure in day to day life at sea level.

Although this isn’t a strong and fast rule. Underwater atmospheric pressure is affected by all sorts of things.

Whilst a watch may be 10ATM, it doesn’t mean that you can dive into 90m deep water. ATM varies underwater so a 10ATM watch is good for swimming, but we strongly recommend that you only dive in a proper diving watch.

As a general rule:

  • 3ATM is splash resistant. Ok for wearing in the rain, hand washing, other occasional contact with water. Most Grace & Co fashion watches are 3ATM.
  • 5ATM is suitable for swimming, fishing, other outdoor activities.
  • 10ATM is suitable for snorkelling and swimming but not for scuba diving.

Remember that steam from a hot sauna, shower or bath can do as much damage to your watch as water. If you get it wet, dry it off.

Your watch may have “ISO 6425” or “Divers” and then a depth number written on the dial or case.

This then is a watch designed for diving.

If it doesn’t have this, a good rule is to consider your watch to be splash resistant and rain resistant, but take it off if you’re going to get any wetter than that.

Looking to buy a watch? Take a look at our watch collections.

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