IP stands for Ingress Protection, and it comes from an international standard called IEC 60529.
The rating is two digits, and each one is a separate test.
The first digit covers solids, mostly dust, on a scale of 0 to 6. The second covers water, on a scale of 0 to 9.
An X does not mean zero. It means the manufacturer never ran that test.
So IPX4 describes water resistance only, with no dust claim at all. IP55 claims both.
The second digit is the only one most earbud buyers need
Level 4 means splashing water from any direction. Level 5 means a low-pressure jet.
Level 7 means immersion in one meter of water for 30 minutes, and that is the first level anyone should call waterproof.
| Water digit | What the lab test is |
|---|---|
| 4 | Splashing from any direction |
| 5 | Low-pressure jet from a nozzle |
| 6 | Powerful jet, higher pressure |
| 7 | Immersion, 1 meter, 30 minutes |
| 8 | Continuous immersion, depth set by maker |
The Sony WF-1000XM6 is rated IPX4. The Soundcore Liberty 5 is rated IP55.
Neither can be dropped in a sink. Neither is designed to survive a swim.
Rain and sweat are not the same test, and sweat is not tested at all
IEC 60529 uses clean fresh water. Nothing in the standard mentions perspiration.
Sweat carries salt, and salt corrodes contacts and eats at adhesives over months.
That is why a bud rated for splashes can still die a year into gym use, without anyone breaking a rule.
Rain is closer to the actual test, which is why IPX4 is a genuinely useful spec for runners and commuters.
The rating tells you what one new sample survived in a lab, not what yours will survive in year three.
What quietly voids the rating
Rinsing under a tap is a jet, not a splash, and it exceeds IPX4 by definition.
Charging while damp is worse. Moisture on the contacts plus current is how corrosion starts.
Heat is the underrated one. A sauna or a hot car degrades the seals and adhesives that make the rating possible.
Physical damage counts too. A bud that has been dropped may still look intact while its seal no longer is.
And every rating is measured on a factory-fresh unit. Gaskets compress, glue ages, and the number does not.
The full standard is published by the IEC, and the digit tables above come straight from it.
Look up IEC 60529, the actual IP standardOfficial IEC webstore listing โ
The charging case is usually rated for nothing
Check the fine print and you will often find the rating applies to the buds alone.
The case has a hinge, a lid seam, and an open charging port. Those are hard to seal and rarely certified.
Leaving a case in a jacket pocket through a downpour is the failure most people never see coming.
Water damage is also a standard warranty exclusion in the United States, even on a rated product.
Manufacturers can and do point to liquid-contact indicators inside the housing.
So treat any IP rating as an insurance policy against accidents, not as permission.
Wipe the buds down after a workout, let them dry before they go back in the case, and the rating will do its job.
For how IPX4 sits among the specs that actually matter on a flagship, see our Sony WF-1000XM6 Review: The 5 Numbers That Decide If It's Worth $330.
If you genuinely need submersion, look for IPX7 or higher and expect a much shorter list of options.
