Is there any rule concerning the use of lower/upper case letters in figures, charts, diagrams etc. to be used in scientific papers?

I tend to use lower case only (e.g., axis labels and legends), but a reviewer recently suggested that I should start each word with a capital letter.

I would be very thankful for any advice!

  • 2
    Formatting rules like that are made by individual journals. If the journal's style guidelines don't cover an issue, it's up to the editor's discretion.
    – Tyler
    Dec 13, 2017 at 20:11

2 Answers 2


There are no absolute rules, but I think the most natural policy is to use title capitalization for major labels (plot title, axis identification, elements in the legend). You may then reserve lower case names for additional minor labeling (like specific, localized features in a figure), although it would not hurt to use title capitalization for everything. Don't use all caps; it looks like you are shouting.


APA style does not force the case of text on the figure, but their example paper uses upper case for the first letter of every word. In fact the APA blog says Figure construction is a creative art that is deceptively complicated. Edward Tufte claims the best statistical graphic ever drawn is this image with a variety of cases

enter image description here

My go to for figures and illustrations is Preparing Scientific Illustrations by Briscoe as I find it a little easier to understand than Tufte's guidance. She says *the use of all upper case letters should be avoided for all but short labels such as a title, because they are not as easy to read as upper and lower case letters.

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