If you're reading such numbers from the data sheet of an item you're going to install somewhere, the data sheet should clearly identify which number goes with which dimension.
If the correspondence is not specified, quite often it does not matter. For calculating the volume of a rectangular prism, or its total area, the order of the numbers is irrelevant. If you need to make a correspondence in order to reduce your anxiety level, you can assign the longest number to length, and assign the other two to width and height in a manner that is satisfying to you. Often, but not always, an object is wider than it is tall--just so it doesn't have a tendency to fall over.
LWH is a common sequence, but it is not universal.
If the correspondence is not specified, quite often it does not matter. For calculating the volume of a rectangular prism, or its total area, the order of the numbers is irrelevant. If you need to make a correspondence in order to reduce your anxiety level, you can assign the longest number to length, and assign the other two to width and height in a manner that is satisfying to you. Often, but not always, an object is wider than it is tall--just so it doesn't have a tendency to fall over.
LWH is a common sequence, but it is not universal.
