What does the IP rating on a headlamp mean?

An IP code is two separate claims printed as one number, and the second digit is not a scale that runs from worse to better. It is the specification most often read as a single word — waterproof — when it is nothing of the kind.

How the code is built

IP is followed by two characters. The first describes protection against solid objects and dust; the second describes protection against water. An X in either position means that property was not assessed, not that it failed. So IPX4 is a lamp assessed for water and not for dust, and IP67 is a lamp assessed for both.

That is the whole grammar. The difficulty is that people read the second digit as a ladder, and it is not one all the way up.

Why IPX4 and IPX7 are not steps on the same ladder

The lower water digits describe water arriving from outside under gravity or pressure: dripping, spraying, splashing from any direction, then jets. The higher digits describe immersion — the product held under still water to a defined depth for a defined time.

These are different situations. A lamp assessed by immersion in still water has not necessarily been assessed against a spray hitting a seam from the side, which is closer to what rain on a hill does. Makers who want to claim both publish both, sometimes as two codes. Where only an immersion figure appears, the splash case has not been stated, and it is fair to ask why.

For camping the practical reading is simple. A splash rating covers rain and a wet pitch. An immersion rating additionally covers the lamp going into a puddle or a stream crossing. Neither is a promise about a lamp left running in heavy rain for hours, because the tests have fixed durations.

What the rating does not cover

Three gaps matter, and none of them is a defect in the standard.

First, the battery door opened in the wet. The rating describes a closed, correctly assembled product. Changing cells in rain puts water inside the sealed volume, where it stays.

Second, the charge port. On a rechargeable lamp the rating usually assumes the port cover is shut and seated. A cover that has stretched, or a magnetic contact strip left dirty, is outside the test conditions.

Third, cold. An IP code says nothing about how a cell behaves near freezing, and cold is a far commoner cause of a lamp underperforming than water is.

Reading it alongside the other figures

The ingress rating sits in the same specification block as the lumen, beam distance and runtime figures published under the ANSI/PLATO FL1 convention, and it should be read as part of that set rather than on its own. A lamp with a strong ingress rating and no stated runtime is still a lamp you cannot plan a night around.

There is also an impact figure on many boxes: a stated drop height in metres onto a defined surface. It is measured the same way for everyone who quotes it, and like the IP code it describes a test rather than a guarantee.

Check these before you order

Write down the full code as printed, including any X, and note whether the maker quotes more than one. Check what the wording says about the charge port — many state that the rating applies with the cover closed. Check whether the maker sells replacement seals or a spare battery door, because on a lamp kept for several seasons that is what decides whether the rating means anything in year three.

Then follow the maker’s instructions on drying, storage and charging. A rating earned on a bench is a description of a new product in a defined test, and the rest is maintenance.