# Correct practice for representing units in figure and text?

What is best practice (if any exist) for representing units of a quantity in figures and text for publications.

I have seen use of both `()` and `[]` for representing units, eg. in a plot if y axis represents velocity then `v``(m/s)` and `v``[m/s]`.

I would like to know what correct: parentheses OR square bracket Or something else?

• What's correct: however you choose to do it (though in terms of dimensional analysis I use [L], for example). Oct 24, 2017 at 16:10
• @SeanRoberson: Square brackets are the expected notation for dimensional analysis. Oct 25, 2017 at 2:41

The publication likely has a style guide. Failing that, just flip through a few published papers until you find an example, then use that

• This is correct, and a more general statement is that typesetting conventions will vary by field and even by sub-discipline. Find good exemplar papers or ask your adviser. Oct 25, 2017 at 2:46
• style guide does not have any mention of that. I scrolled through few publications and found that both parentheses and square brackets are used. Thanks.
– pkj
Oct 27, 2017 at 5:23
• @pkj If papers in the journal use different conventions, then don't worry about it. Just make sure that the meaning of what you are writing is clear. Sep 28 at 12:24

With respect to units, brackets are frequently used in two distinct ways:

1. They are placed around a variable to signify the units of that variable, such as in [v] = m/s. See this answer in the physics stack exchange for an excellent description of the conventions.

2. They are placed around the units to separate them from a preceding mathematical expression and, in the context of figures, to make labels like log(v [m/s]) more readable.

Parentheses may be used in place of brackets for (2), but not (1). Whether they are or aren't is—as others have said—a matter of style and depends on the journal and field.

This seems a rather trivial question, where the answer is "it depends on your field".

However, the importance of the representation of objects cannot be understated. Your field may be full of errors, it is good practice to correct them and propose best practices. For the best practice, you have to refer to the following literature:

For example, the first publication describes that, based on the other publications

Square brackets enclose suffixes of unit symbols that change the meaning of a unit stem. [...] For example 1 m H2O is written as “ m[H2O]” in The Unified Code for Units of Measure because the suffix H 2O changes the meaning of the unit atom for meter (length) to a unit of pressure.