A devices IP rating is a combination of two numbers, the first being Dust Protection and the second Water Protection.

For example, a device could have an IP rating of IP68. This would mean, referring to the table underneath that 6 is completely dust proof, while the 8 shows its waterproof for up to 2 meters for half an hour (30 minutes)

Dust protection

LevelEffective againstDescription
0-No protection
1>50 mmAny large surface of the body, such as the back of a hand, but no protection against deliberate contact with a body part.
2>12.5 mmFingers or similar objects.
3>2.5 mmTools, thick wires, etc.
4>1 mmMost wires, slender screws, large ants etc.
5Dust protectedIngress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment.
6Dust tightNo ingress of dust; complete protection against contact (dust tight). A vacuum must be applied. Test duration of up to 8 hours based on air flow.

Water Protection

LevelProtection againstDescription
0-No protection
1Dripping WaterDripping water (vertically falling drops) shall have no harmful effect.
2Dripping water when tilted at 15°Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle of 15° from its normal position.
3Spraying waterWater falling as a spray at any angle up to 60° from the vertical shall have no harmful effect.
4Splashing of waterWater splashing against the enclosure from any direction shall have no harmful effect.
5Water jetsWater projected by a nozzle (6.3 mm) against enclosure from any direction shall have no harmful effects.
6Powerful water jetsWater projected in powerful jets (12.5 mm nozzle) against the enclosure from any direction shall have no harmful effects.
7Immersion, up to 1 m depthIngress of water in harmful quantity shall not be possible when the enclosure is immersed in water under defined conditions of pressure and time (up to 1 m of submersion).
8Immersion, 1 m or more depthThe equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. However, with certain types of equipment, it can mean that water can enter but only in such a manner that it produces no harmful effects.