Tool

What does a water-resistance rating mean?

Enter the rating on the dial or caseback to convert it and see what it is usually considered safe for. A rating is a lab pressure test, not a depth you can take the watch to.

Unit

Dials often say "10 ATM", "100 m" or "330 ft". 1 bar or 1 ATM counts as 10 m.

Result

Metres
– m
Feet
– ft
Bar / ATM
– bar

Guidance, not a guarantee. Seals age: have water resistance tested every year or two, screw the crown down before swimming, and never use the crown or pushers underwater.

Water resistance chart

  1. Under 30 m · Keep it dry

    Everyday wear and the odd splash. Avoid: rain for long, hand washing, showers, swimming.

  2. 30–49 m · Splashes and rain

    Rain, splashes, washing your hands. Avoid: showers, swimming, snorkelling, diving.

  3. 50–99 m · Light swimming

    Short swims at the surface, rain, hand washing. Avoid: snorkelling, diving, jumping in, hot showers and saunas.

  4. 100–199 m · Swimming and snorkelling

    Pool and sea swimming, snorkelling, water sports at the surface. Avoid: scuba diving, unless the watch is sold as a dive watch.

  5. 200–999 m · Recreational diving

    Swimming, snorkelling and recreational scuba, if it is certified to ISO 6425 (marked DIVER'S). Avoid: saturation diving without a helium escape valve.

  6. 1,000 m and up · Deep and professional diving

    Everything above, plus deep technical dives within the rating. Avoid: saturation diving, unless the watch has a helium escape valve or is rated for it.

Why 30 m does not mean 30 metres deep

  • The rating is a static pressure a new watch passed in a test (ISO 22810), with the watch held still.
  • Swimming strokes, diving in and jets of water add pressure, and so do sudden temperature changes.
  • Gaskets dry out and wear with age, so an older watch may no longer meet its rating.
  • Dive watches tested to ISO 6425 must be rated 100 m or more and carry the word DIVER'S.

Common ratings converted

On the dialMetresFeetUsually fine for
3 ATM 30 98 Splashes and rain
5 ATM 50 164 Light swimming
10 bar 100 328 Swimming and snorkelling
200 m 200 656 Recreational diving
300 m 300 984 Recreational diving
1,000 feet 304.8 1,000 Recreational diving

See also: all watch tools · watch guides