ATM vs. IP Ratings: The Truth About Waterproof
A sudden downpour during a morning run can instantly turn an expensive smartwatch into a non-functional paperweight. If you have ever hesitated before wearing a fitness tracker in the shower or pool, you already know the anxiety of risking your personal electronics around moisture.
Device manufacturers often promise safety by stamping their products with terms like “5 ATM” or “IP68.” However, these two rating systems measure entirely different types of environmental resistance, and misinterpreting them frequently leads to costly hardware failure. Learning how these testing standards actually function under real-world pressure helps you select the correct device for your lifestyle and protect your technology from preventable water damage.
Key Takeaways
- ATM ratings measure how well a device withstands physical water pressure, with 1 ATM equaling the static atmospheric pressure at sea level.
- IP ratings measure the physical barrier protection of a casing, where the first digit indicates solids protection on a scale of 0 to 6 and the second digit indicates fresh water protection from 0 to 9K.
- Static laboratory testing does not account for real-world motion, meaning an IP68 device can still fail during active swimming due to dynamic water pressure.
- Environmental factors like hot steam, sauna heat, chlorine, and saltwater degrade rubber seals and adhesives over time, regardless of a device’s initial ratings.
- Select a device with at least a 5 ATM rating for pool swimming, and look for specialized ISO 6425 certification for deep-water diving or high-impact water sports.
ATM (Atmosphere) Ratings
Wearable devices designed for water exposure often carry a rating measured in atmospheres. This metric evaluates how well a device resists the physical pressure of water, which is essential for anything worn on the wrist while swimming or submerged.
Definition and Scientific Basis
The abbreviation ATM stands for atmosphere, a unit of physical pressure. One ATM represents the normal ambient pressure of the air at sea level, which is approximately 14.7 pounds per square inch.
As an object descends underwater, the weight of the water above it exerts additional force. For every ten meters of depth, the water pressure increases by approximately one ATM.
A device rated for a specific number of atmospheres is built to withstand that exact static pressure without allowing water to bypass its protective seals.
Testing Methodology
To certify a device under ATM standards, manufacturers perform laboratory tests dictated by international guidelines such as ISO 22810. These evaluations take place in controlled chambers where the device is subjected to specific levels of static air and water pressure for a set duration.
Technicians look for leaks by measuring air pressure changes inside the device or by physically inspecting the seals after submersion. Because these tests occur in motionless water under stable temperatures, they simulate a state of absolute stillness rather than actual active use in a pool or ocean.
The Common Tiers
ATM ratings are categorized into standard tiers that correspond to theoretical depths. A rating of 3 ATM theoretically protects against pressure down to 30 meters, while 5 ATM corresponds to 50 meters, 10 ATM to 100 meters, and 20 ATM to 200 meters.
However, these depths are calculated based on static pressure. In practice, a 3 ATM device is only protected against light splashes and rain.
A 5 ATM rating is generally suitable for shallow swimming, whereas 10 ATM and 20 ATM ratings are engineered for high-pressure environments like snorkeling and high-speed water sports.
IP (Ingress Protection) Ratings
Smartphones and many everyday accessories use a different classification system to indicate how well their outer casings block foreign materials. This system addresses both solid particles like dust and liquid intrusions like rain or accidental submersions.
The Ingress Protection Standard
The IP rating, which stands for Ingress Protection, is an international standard established by the International Electrotechnical Commission under standard IEC 60529. This rating provides a clear, uniform metric instead of vague marketing terms like dustproof or water-resistant.
An IP rating consists of the letters IP followed by two digits. Each digit represents a specific level of tested protection, allowing consumers to know exactly what elements a device can withstand.
The First Digit (Solids Protection)
The first digit in an IP rating indicates the level of protection against solid foreign objects, ranging on a scale from 0 to 6. A rating of 0 means there is no protection at all.
Ratings 1 through 4 measure defense against objects of varying sizes, such as fingers or small copper wires. A rating of 5 means the device is protected against harmful dust deposits that could interfere with operation, while a rating of 6 signifies that the device is completely dust-tight, offering absolute protection against any solid particle entry.
The Second Digit (Liquids Protection)
The second digit measures the device’s defense against fresh water, graded on a scale from 0 to 9K. Lower numbers, such as 1 through 4, indicate protection against falling water droplets, light splashes, or spraying at an angle.
Ratings of 5 and 6 certify resistance to low and high-pressure water jets. Ratings of 7 and 8 deal with actual submersion, certifying that a device can survive being underwater at specific depths, usually up to 1.5 meters, for up to thirty minutes.
The highest rating, 9K, protects against high-pressure, high-temperature steam washdowns.
Pressure Limits vs. Physical Barriers
Although both systems assess a device’s ability to survive wet environments, they serve entirely different purposes. Choosing the correct wearable depends on recognizing how pressure resistance differs from simple liquid exclusion.
Structural Differences in Measurement
The primary difference lies in the focus of the testing. IP ratings evaluate the physical structural barriers of a device to prevent the entry of solid dust particles and non-pressurized liquids.
The main goal is to keep the inside dry during temporary exposure. ATM ratings, by contrast, focus exclusively on the integrity of the device under significant, sustained hydraulic pressure.
A device might have tight seals that block dust, but those same seals might fail and buckle under the crushing weight of deep water.
Static Lab Tests vs. Real-World Motion
Standard IP tests are conducted in static environments where the device is lowered gently into still water and left undisturbed. This testing does not account for the dynamic force of movement.
When a person swims, the motion of their arms through the water creates localized high-pressure zones that exceed the limits of a standard IP68 rating. ATM testing simulates these higher pressures, making it a much more reliable indicator of whether a device can handle active aquatic activities.
Dual-Rated Devices
Certain premium smartwatches and rugged outdoor devices display both an IP rating and an ATM rating. This dual certification means the device has successfully passed separate standardized tests.
For example, an IP68 and 5 ATM rating guarantees that the device is entirely sealed against fine dust particles while also possessing the structural strength to withstand the static pressure of shallow swimming. The two certifications complement each other to verify complete environmental protection.
Environmental Variables and Common Failure Points
Lab certifications are earned under highly controlled, pristine conditions that rarely match daily use. Real-world environments introduce several active elements that can quickly compromise a device’s seals.
The Impact of Dynamic Pressure
Dynamic pressure is the force generated by motion. When you plunge into a pool or splash your arms while swimming, the velocity of your movement dramatically increases the water pressure on the device’s gaskets.
A device rated only for static submersion may experience localized pressure spikes that exceed its tested limits, forcing water past the rubber barriers and causing immediate internal damage.
Temperature and Steam
Standard water resistance tests are conducted using fresh water at stable, cool temperatures. Hot showers, steam rooms, and saunas introduce hot water and water vapor.
High temperatures cause the metal and plastic components of a device to expand at different rates, which can warp or loosen internal gaskets and melt the adhesives holding the casing together. Furthermore, tiny steam molecules can easily penetrate seals that are otherwise rated to block liquid water.
Chemical Degradation
Water resistance is not a permanent state, and exposure to various chemicals accelerates the aging of protective seals. Chlorine in swimming pools, salt in seawater, and soaps or shampoos in the shower dry out and degrade rubber gaskets over time.
Sunscreen, lotion, and insect repellent can also chemically react with the exterior adhesives of a device, causing the protective barriers to crack, shrink, and eventually fail.
Matching Activities to Ratings
Selecting the correct rating involves assessing your daily routine and recreational activities. Matching your specific habits to the appropriate certification prevents unexpected hardware failures and avoids overpaying for unnecessary specifications.
| Rating | Protection Type | Safe Activities | Unsafe Activities |
| IP67 | Dust and temporary splashes | Rain, handwashing, heavy sweat | Swimming, showering, snorkeling |
| IP68 | Dust and shallow immersion | Accidental submersion in shallow water | Lap swimming, diving, water sports |
| 3 ATM | Low static pressure (30 meters) | Rain, splashes, washing dishes | Swimming, bathing, snorkeling |
| 5 ATM | Medium static pressure (50 meters) | Pool swimming, shallow snorkeling | Scuba diving, high-speed water sports |
| 10 ATM / 20 ATM | High static pressure (100+ meters) | Surfing, swimming, sailing | Deep scuba diving without ISO certification |
Everyday Use and Low-Risk Environments
For typical daily routines, high-level water protection is rarely necessary. Devices with an IP67 or IP68 rating, or a 3 ATM rating, are perfectly adequate for handling light rain, accidental kitchen spills, intense gym sweat, and dusty outdoor environments.
These specifications ensure that your device survives handwashing and minor household mishaps without issue, provided it is not submerged for extended periods.
Swimming, Water Sports, and Snorkeling
Active surface water activities require a step up in pressure resistance. A minimum rating of 5 ATM is recommended for swimming laps in a pool, shallow snorkeling, or light boating.
At this level, the device can withstand the dynamic pressures associated with basic arm movements in the water. However, devices with only IP ratings should generally be kept out of the pool, as they lack the structural reinforcement to handle continuous movement under water.
High-Impact and Deep-Water Activities
For demanding environments like jet skiing, surfing, or scuba exploration, specialized standards are required. High-speed water sports subject devices to severe dynamic pressure impacts, requiring at least a 10 ATM or 20 ATM rating.
For actual underwater exploration, standard consumer ratings are insufficient; instead, look for devices certified under ISO 6425, which is the official international standard for professional diving watches, featuring rigorous testing for thermal shock, magnetic resistance, and structural durability.
Conclusion
Deciphering the actual capabilities of your electronics requires looking past simplistic marketing terms like waterproof or water-resistant. ATM ratings measure a device’s structural integrity under hydraulic pressure, while IP ratings evaluate the physical barriers preventing dust and liquids from entering the casing.
To protect your investment, rely strictly on these standardized technical certifications to match your gear to your specific lifestyle. Choosing a device with the precise rating required for your activities ensures your technology survives your daily habits and outdoor adventures.
Frequently Asked Questions
Can I wear my 5 ATM smartwatch in a hot shower?
No, you should not wear a 5 ATM smartwatch in a hot shower. High temperatures and steam cause metal and plastic parts to expand at different rates, which warps the protective rubber gaskets. Additionally, soap and shampoo chemicals degrade the adhesive seals over time, eventually allowing moisture to seep inside the device.
Is an IP68 phone safe to take swimming in the pool?
No, an IP68 rating does not guarantee that your phone is safe for swimming. IP68 tests are conducted in static, motionless water, which does not account for the dynamic pressure created by swimming strokes. The force of your movements can easily push water past the physical seals, leading to permanent liquid damage.
What does a 3 ATM rating actually mean for daily use?
A 3 ATM rating means your device can survive minor splashes, rain, and handwashing, but it should never be submerged. This rating only protects against light, accidental contact with fresh water under static pressure. It lacks the structural reinforcement needed to withstand the pressures of swimming, showering, or bathing.
Does salt water ruin a water-resistant smartwatch?
Yes, salt water can severely damage and corrode your water-resistant smartwatch. Ocean water contains salt crystals that dry out and degrade rubber seals, making them brittle and prone to leaking. If you wear your device in the ocean, always rinse it thoroughly with fresh water immediately afterward to remove salt deposits.
Why do some rugged watches have both IP68 and 5 ATM ratings?
Some devices carry both ratings to prove they are entirely dustproof while also being structurally reinforced against water pressure. The IP68 certification guarantees that fine dust and sand cannot enter the casing during dry activities. The 5 ATM rating certifies that the internal components can withstand the physical force of shallow swimming in pools or lakes.
About the Author: Julio Caesar
