The IP Rating (or International Protection Rating, sometimes also interpreted as Ingress Protection Rating) consists of the letters IP followed by two digits and an optional letter. It classifies the degrees of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water in the casing/enclosure. The standard aims to provide users with more detailed information than vague marketing terms such as waterproof.
The digits (characteristic numerals) indicate conformity with the conditions summarized in the tables below. Where there is no protection rating with regard to one of the criteria, the digit is replaced with the letter X.
For example, an electrical socket rated IP22 is protected against insertion of fingers and will not be damaged or become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for indoor use.
First Digit
The first digit indicates the level of protection that the enclosure provides against access to hazardous parts (e.g., electrical conductors, moving parts) and the ingress of solid foreign objects.
| Level | Object size protected against | Effective against |
| 0 | — | No protection against contact and ingress of objects |
| 1 | >50 mm | Any 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 mm | Fingers or similar objects |
| 3 | >2.5 mm | Tools, thick wires, etc. |
| 4 | >1 mm | Most wires, screws, etc. |
| 5 | dust protected | Ingress of dust is not entirely prevented, but it must not enter in sufficient quantity to interfere with the satisfactory operation of the equipment; complete protection against contact |
| 6 | dust tight | No ingress of dust; complete protection against contact |
Second Digit
Protection of the equipment inside the enclosure/casing against harmful water ingress.
| Level | Protected against | Details |
| 0 | not protected | — |
| 1 | dripping water | Dripping water (vertically falling drops) shall have no harmful effect. |
| 2 | dripping water when tilted up to 15° | Vertically dripping water shall have no harmful effect when the enclosure is tilted at an angle up to 15° from its normal position. |
| 3 | spraying water | Water falling as a spray at any angle up to 60° from the vertical shall have no harmful effect. |
| 4 | splashing water | Water splashing against the enclosure from any direction shall have no harmful effect. |
| 5 | water jets | Water projected by a nozzle against the enclosure from any direction shall have no harmful effects. |
| 6 | powerful water jets | Water projected in powerful jets against the enclosure from any direction shall have no harmful effects. |
| 7 | immersion up to 1 m | Ingress 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). |
| 8 | immersion beyond 1 m | The equipment is suitable for continuous immersion in water under conditions which shall be specified by the manufacturer. NOTE: Normally, this will mean that the equipment is hermetically sealed. However, with certain types of equipment, it can mean that water can enter but only in such a manner that produces no harmful effects. |
