Saudi Luxury / Watch basics
Water resistance: what 30, 50, 100 and 200 metres really allow
See which activities each depth rating allows, from hand washing to diving, and how to keep a watch's seals doing their job.
The metres on a watch are a pressure rating expressed as a depth, not a depth you can safely take the watch to. As a rule, 30 metres copes with rain and hand washing, 50 metres with a short, calm swim, 100 metres with regular swimming and snorkelling, and 200 metres is where diving begins.
The ratings in practice
The same rating may be written in metres, bar or ATM: 10 bar and 10 ATM both mean 100 metres.
| Rating | Fine for | Keep it away from |
|---|---|---|
| 30 m (3 bar) | Rain, splashes, washing your hands | Swimming, showers |
| 50 m (5 bar) | Short, calm swims, if the maker allows | Snorkelling, diving into a pool |
| 100 m (10 bar) | Swimming, snorkelling | Scuba diving |
| 200 m (20 bar) | Swimming and recreational diving, if it is built as a dive watch | Saturation diving |
Makers write their own charts, so check the manual: some permit swimming at 50 metres, others are stricter. ISO 22810 is the general standard for water-resistant watches. Dive watches fall under a separate standard, ISO 6425, which starts at 100 metres and also requires a way to time a dive that can be read in the dark. A dial marked “Diver’s” with a depth, such as “Diver’s 200m”, claims that standard; a plain “200m” does not. Our dive watch guide explains what else to check.
Matching the rating to the watch
A slim dress watch such as the Orient Classic Bambino RA-AP0105Y, rated to 30 metres, should come off before the pool. If you swim regularly, 100 metres, as on the Seiko 5 Sports SRPL77K1, is the sensible minimum. For snorkelling trips or diving, the Seiko Prospex SRPL53K1 adds 200 metres and a one-way bezel. Ratings far beyond that, such as the 1,220 metres of the Rolex Sea-Dweller 126600, usually mean a thicker case most people never need.
The strap matters as much as the case. Leather is spoiled by water whatever the rating, so swim on a steel bracelet, rubber or fabric strap.
For an everyday watch, start with watches rated 100 to 199 metres. The filter misses some listings, so check the spec table too.
Habits that keep a watch sealed
The rating describes a new watch. Gaskets harden with age, heat, sweat, chlorine and salt.
- Push the crown fully in, or screw it down, before water touches the watch.
- Do not press chronograph pushers in water unless the maker allows it.
- Rinse in fresh water after the sea or a chlorinated pool.
- Skip hot showers and saunas: heat and sudden temperature changes are hard on seals.
- Ask for a pressure test at every battery change or service, and more often if you swim with the watch regularly.
If water gets in
Mist under the crystal or a drop on the dial means the seals have failed. Take the watch off, keep the crown pushed in, do not open it or heat it, and take it to a watchmaker as soon as you can. Moisture left inside corrodes the movement, and drying it out early costs far less than replacing corroded parts. Fogging that clears on its own is still a warning.
For the engineering behind the number, Watch Codex explains how gaskets, crowns and pressure tests keep water out.