Watch Water Resistance

Watch Water Resistance

What Do Watch Water Resistance, ATM, Depth, Diver’s, and IP Ratings Mean?

A watch’s resistance to water is one of the most important features to look for when purchasing. Whether you’re a casual wearer or a professional diver, choosing the proper watch for your needs requires familiarity with the many words and grades used to characterise a watch’s water resistance. This primer will explain what terms like “water resistant,” “ATM,” “depth rating,” “diver’s watch,” and “IP” (ingress protection) imply in the context of timepieces. By the end of this primer, you’ll have a firm grasp of these concepts and be ready to make an educated choice when purchasing your next timepiece.

Watch Water Resistance

The term “water resistance” describes a watch’s capacity to resist damage from water and moisture. This function is crucial for preserving the watch’s accuracy and functionality by preventing water from entering the watch and damaging the mechanism, dial, and other components.

Factors affecting water resistance

The degree to which a watch can withstand water is dependent on several aspects, such as:

  1. Gaskets: Watertight seals made of rubber or silicone surround the case’s openings at the crown and rear.
  2. Construction of the case and crown: A water-resistant watch can have a screw-down case back and crown. This helps the watch to be more effectively sealed.
  3. Crystal composition: sapphire, mineral, or acrylic crystals can be used in watches, all of which add to the overall water resistance of the timepiece.
  4. Age and upkeep of the watch: As the gaskets wear out and the watch ages, it may require maintenance to retain its water resistance.

How to maintain water resistance

To keep your watch watertight:

  1. Keep an eye on the gaskets and replace them when necessary.
  2. Don’t let the watch get too hot or cold, which could damage the gaskets.
  3. Get your watch professionally repaired regularly to keep the seal in good condition and the timepiece running smoothly.
  4. Before submerging your watch in water, ensure the crown is securely fastened.
  5. Do not use the crown or pushers when the watch is damp.

ATM (Atmospheres) Ratings

A watch’s water resistance is measured in atmospheres (or “ATM” for short). The pressure at a depth of 10 metres (33 feet) in water is roughly equivalent to one atmosphere. A watch’s water resistance is measured in atmospheres of pressure (ATMs).

Common ATM ratings and their meaning

3 ATM (30 meters / 100 feet)

Good for regular use; it doesn’t mind getting wet occasionally. Not safe for use while swimming or submerged.

5 ATM (50 meters / 165 feet)

Useful for shallow water swimming but not for diving or other activities involving fast-moving water.

10 ATM (100 meters / 330 feet)

It is suitable for swimming, snorkelling, and other water-based activities, but scuba diving should be avoided with this gear.

20 ATM (200 meters / 660 feet)

Allows for participation in high-impact water activities as well as recreational scuba diving. Not suitable for professional diving or other activities in deep water.

50 ATM (500 meters / 1,650 feet)

Developed specifically for use in professional diving and other activities that take place in deep water. These watches often come equipped with additional components, such as a helium escape valve to withstand higher pressure.

Selecting a watch based on ATM ratings

When looking for a watch, it is important to consider your lifestyle and the kinds of activities you plan to participate in. Choose a watch with an appropriate ATM rating to guarantee it can withstand the water exposure you intend to subject it to. It is important to remember that the water resistance may be lower than the grade given because of variables such as worn gaskets or faulty crown sealing. Keep this in mind. The watch’s water resistance can be preserved with proper and routine maintenance and care.

Depth Ratings

The maximum depth to which a watch may be immersed without damage is indicated by its depth rating. They are closely related to the ATM ratings and are often given in metres or feet. Manufacturers of watches often provide depth ratings as an easily understood indicator of their goods’ ability to withstand water.

Relationship between ATM ratings and depth ratings

We already know that the pressure at a depth of 10 metres (33 feet) in water is equal to one atmosphere (ATM), measured in air pressure units. So, the ATM rating can be converted to a depth rating by multiplying by 10. One example is the 5 ATM watch, which can be worn at a depth of 50 meters (165 feet) without damage.

Limitations of depth ratings

Note that depth ratings aren’t always accurate because they don’t consider water pressure variations caused by movement or temperature swings. A watch’s water resistance may be lower than its depth certification indicates. For instance, the wearer’s movements might raise the water pressure on a watch, making it unsafe for use when swimming or snorkelling if the watch is only approved for 50 metres. Check the watch’s ATM rating and the manufacturer’s intended use guidelines to ensure it can withstand the water depths you’ll be diving to. The watch’s ability to resist water damage over time depends on more than the initial construction.

Diver’s Watches

Divers’ watches are timepieces modified for use in the water, most commonly when scuba diving. They can endure the intense water pressure found at great depths; some even come equipped with extra functions to help divers in their work. Compared to standard wristwatches, Diver’s watches often include increased water resistance ratings, stronger construction, and greater legibility.

ISO 6425 standard for diver’s watches

The International Standards Organisation (ISO) has published a list of requirements for a diver’s watch. ISO 6425 addresses many facets of a diver’s watch, such as:

  1. Waterproofing: A 100-meter (330-foot) depth rating or higher is necessary. To pass the test, the watch must endure an overpressure of 25% above its certified water resistance.
  2. Timekeeping precision: the watch must keep perfect time on land and in the deep sea.
  3. Readability and visibility: The watch you wear should have clear markings that glow in the dark so you can see them even when swimming in dim settings. It should have a unidirectional rotating bezel with minute indications to aid divers in keeping track of time.
  4. Resistance to magnetic fields, shocks, and chemicals: A diver’s watch must withstand the magnetic fields, shocks, and corrosive elements frequently encountered while engaging in diving activities.

Examples of popular diver’s watches

Here are a few examples of popular dive watches:

  1. Rolex Submariner: A legendary diver’s watch with a water resistance of 300 metres (1,000 ft).
  2. Omega Seamaster 300 Metre Deep Diver: This watch has a helium escape valve and can withstand depths of up to 300 metres (1,000 feet), making it a top pick among scuba divers.
  3. Diver’s Seiko Prospex: The Seiko Prospex line is well-known for its affordable and trustworthy diving watches, providing water resistance ratings of up to 200 metres (660 ft).
  4. Oris Aquis Date: This fashionable diving watch is water-resistant for three hundred metres (one thousand feet) and has a unidirectional rotating bezel with a ceramic insert.

When shopping for a diver’s watch, it’s important to look for certification to the ISO 6425 standard and ensure it has the functionality and aesthetic you want.

IP (Ingress Protection) Ratings

The Ingress Protection (IP) rating system is standardised for describing a device’s resistance to the infiltration of solid particles (such as dust) and liquids (such as water). Regarding water and dust protection, IP ratings are typically given to electronic devices like smartphones and cameras, but they can also be applied to timepieces.

IP rating system

The “IP” followed by two digits designate the IP rating scale:

First digit – protection against solids:

Protection levels from the airborne variety of dust and other solids range from 0 (no protection) to 6 (maximum protection).

Second digit – protection against liquids:

From zero (completely unprotected) to eight (fully protected against prolonged immersion in water), depending on the conditions.

For instance, a watch with an IP classification of IP68 is protected against dust and can tolerate being submerged in water indefinitely.

Comparing IP ratings with ATM and depth ratings

The IP certification provides a more all-encompassing picture of a watch’s resistance to dust and water than the ATM or depth rating, emphasising water resistance but not dust resistance. While IP ratings are occasionally found on timepieces, most companies employ either the ATM or depth rating system instead.

Remember that a higher second number in an IP rating indicates greater water resistance while shopping for a watch. For instance, a watch with an IP67 rating is less water-resistant than one with an IP68 rating. Knowing the manufacturer’s requirements for the watch’s water resistance is also important, as IP ratings are often tested under laboratory settings that don’t accurately reflect real-world use.

Read Also: Watch Crown Types, Materials, Purpose, and Maintenance


When shopping for a watch, it’s important to learn about its water resistance, ATM rating, depth rating, diver’s watch, and IP rating. A watch’s resistance to water and other elements is shown by its rating, so you may buy one that will last through your planned activities with confidence.

Remember that water resistance can degrade over time due to ageing gaskets and temperature changes. To keep your watch watertight, it is important to service it regularly and replace the gaskets as the manufacturer directs.

Taking them into account and familiarising yourself with the various ratings and phrases associated with water resistance can help you choose a functional and durable watch.

What does ATM mean in watch water resistance ratings?

ATM, short for atmospheres, is a unit of measurement used to express a watch's water resistance. One atmosphere is approximately equal to the pressure exerted at a depth of 10 meters (33 feet) of water. Watches with higher ATM ratings can withstand higher water pressure and are suitable for activities such as swimming, snorkeling, or diving, depending on the specific rating.

How do I know if a watch is suitable for swimming or diving?

To determine if a watch is suitable for swimming or diving, consider its ATM or depth rating. Generally, a watch with a minimum rating of 5 ATM (50 meters) is suitable for swimming in shallow water, while a watch with a rating of 10 ATM (100 meters) or higher is suitable for snorkeling and water sports. For scuba diving, a diver's watch that meets the ISO 6425 standard with a minimum water resistance of 20 ATM (200 meters) is recommended.

Are IP ratings used for watches, and how do they compare to ATM ratings?

While IP (Ingress Protection) ratings are more commonly used for electronic devices like smartphones and cameras, they can also be applied to watches to indicate their resistance to water and dust. An IP rating consists of two digits, with the first representing protection against solids and the second representing protection against liquids. In general, a higher second digit signifies better water resistance. However, watch manufacturers typically use ATM or depth ratings to indicate water resistance, making it essential to understand both systems when selecting a watch.

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