Guide
IP68 or 5 ATM: what water ratings mean.
A phone says IP68, a watch says 5 ATM, a ring says water resistant to 100 m. They sound comparable, and they are not: the ratings come from different standards and are tested in different ways.
In short. IP ratings come from the IEC 60529 standard: the first digit is for dust, the second for water. IP67 means a dip of up to 1 m for 30 minutes; for IP68 the maker sets the depth and the time, so two IP68 phones can differ. Ratings in metres or ATM come from ISO 22810, a standard for watches: Apple rates most of its watches to 50 m under it, and says that means swimming, not diving. No rating is permanent, and a rating for immersion says nothing on its own about jets of water, soap or a sauna.
IP: two digits, two kinds of protection
- The first digit is for solids such as dust. 6, the highest, means dust-tight.
- The second digit is for water, from drips to immersion. 7 means immersion up to 1 m for 30 minutes. 8 means immersion beyond that, under conditions the maker states.
- An X means that part was not rated: IPX7 says nothing about dust.
- Not a ladder above 6. The water ratings stop adding up after the jet tests: a device rated IPX7 or IPX8 for immersion does not have to pass the jet tests as well.
The conditions behind IP68 are the maker’s to state, and they vary. Apple lists iPhones rated IP68 to depths from 2 m to 6 m, each for up to 30 minutes, depending on the model.
ATM and metres: a watch standard
Watches and many wearables give a pressure rating instead: 50 m, often written as 5 ATM, or 100 m, 10 ATM. For watches it comes from ISO 22810. The depth describes a test, not a diving limit. Apple rates most of its watches to 50 m under ISO 22810, and says they suit shallow water, such as swimming in a pool or the sea, but not diving, water skiing or other fast water.
What no rating promises
- It wears off. Apple says water resistance is not a permanent condition and can diminish over time, and that a watch cannot be rechecked or resealed.
- Soap, lotions and heat. Apple’s list of things to avoid with its watches includes soapy water, as in the shower or the bath, lotions and sunscreen, steam rooms and, for most models, saunas.
- Warranty. Apple says liquid damage is not covered by its iPhone warranty, though consumer law may still give you rights.
Before you swim with a wearable
- Find the standard, not only the number. IEC 60529 for IP codes, ISO 22810 for metres or ATM.
- Read the maker’s list. Showers, swimming, the sea, hot tubs and saunas are separate questions.
- Ask about cover. Whether water damage is under warranty, and for how long.
Our ring’s rating
For a ring you wear all day, water protection is not optional, so it is part of Lychnos Ring’s design from the start. The body is sealed, the ring charges without contacts, and its microphone sits behind a waterproof membrane. Our target is IP68, for hand washing, showers and rain; whether it suits swimming depends on testing. The rating we state will be the one we measure, with what it allows. It is in development. More on choosing a ring: how to choose a smart ring.
Sources, read 4 November 2026: Apple, water resistance of Apple Watch and splash, water and dust resistance of iPhone; the definitions of the IP code in IEC 60529, as summarised in Wikipedia’s article on the IP code. General information.
Questions
Is IP68 better than 5 ATM?
They measure different things. IP68 is a dust and immersion rating under IEC 60529, with the depth and time set by the maker; 5 ATM, or 50 m, is a pressure rating under ISO 22810, the watch standard. Read what each maker allows: showers, swimming, the sea.
Can I shower with a water-resistant watch or ring?
Check the maker’s guidance. Apple, for example, lists soapy water, as in the shower, among the things that can affect its watches’ water resistance.