An IP rating, or ingress protection rating, is a laboratory-certified industrial rating to a piece of electronic equipment or an enclosure for electrical equipment, used to explain the degree of protection provided against intrusion of debris and water, as well as accidental contact (including body parts like fingers or hands) to critical components.  This internationally recognized rating system was developed by the IEC (International Electrotechnical Commission) and is used heavily in Europe and Asia, with new adherents in North America.

The IP rating standard seeks to provide consumers more specific information than vague terms like “waterproof.” The IP rating consists of two digits, each representing different forms of environmental influence. The first digit represents protection against ingress of solid objects, while the second digit represents protection against ingress of liquids. The higher the value of each digit, the greater the protection. The digit 0 is used where no protection is provided.  For instance, a product rated IP45 would be better protected against environmental factors than another similar product rated IP31. Alternatively, a smartphone rated at IP58 is dust resistant and can be immersed in 1.5 meters of freshwater for up to 30 minutes.


IP First Digit

Ingress of Solid Objects

Second Digit

Ingress of Liquids

0 No protection No protection
1 Protected against solid objects over 50mm, such as hands, large tools, but not against deliberate contact with a body part. Protected against vertically dripping water or condensation.
2 Protected against solid objects over 12.5mm, such as hands, fingers, or large tools. Protected against falling drops of water when the enclosure is tilted at an angle of 15 degrees from its normal position (from vertical).
3 Protected against solid objects over 2.5mm, such as tools or thick wires. Protected against water falling as spray from any direction, even if the case is disposed up to a 60 degree from vertical.
4 Protected against solid objects over 1.0mm, such as wires, thin screws, and large insects. Protected against splashing or spray of water from any direction.
5 Dust protected (ingress of dust is not entirely prevented, but will not interfere with equipment operation). Protected against low pressure water jets (6.3mm nozzle) from any direction.
6 Dust tight (entirely protected against dust ingress) and complete protection Protected against high pressure water jets (12.5mm nozzle)  from any direction.
7 N/A Protected against short periods of immersion in water (up to 1 meter of submersion depth).
8 N/A Protected against continuous periods of immersion in water (up to a specified pressure, typically hermetically sealed).
9K N/A Protected against close-range high pressure, high temperature spray downs (steam-jet cleaning).

Source: https://www.kdedirect.com/blogs/news/ip-ratings-drones