How to Refer Readers to the Online Version in a Figure Caption

If a figure is printed in grayscale but shown in color online, tell readers where they can see the color version. A short note at the end of the figure caption is usually clear and sufficient. The journal’s author instructions take priority: some publishers prescribe exact wording or specify whether the note belongs in the caption or elsewhere.

A clear default formulation

When no required wording is given, write:

The color version of this figure is available online.

You can also write “A color version of this figure is available in the online article” if that fits the journal’s terminology. These options are direct and avoid asking readers to infer what “web version” means.

Some journals use a longer formula, for example:

For interpretation of the colors in this figure, see the online version of this article.

That wording is appropriate when the color choices are needed to interpret the figure. It is not necessary to reproduce it if the journal does not request it; a shorter note is easier to read.

Put the note after the figure description

A caption should first identify and explain the figure. Add the online-color note after that description, usually as the final sentence. For example:

Figure 2. Mean response time by treatment group. Error bars show 95% confidence intervals. The color version of this figure is available online.

This makes the caption informative on its own and keeps the publication-format note separate from the scientific description. If the journal requires a particular caption format, such as a standalone color note or a note in the figure legend, follow that format instead.

Check that color is not doing all the work

A note directing readers online does not make an otherwise unreadable grayscale figure accessible. If two series can only be distinguished by color, consider adding different line styles, markers, labels, or patterns as well. This helps readers who cannot distinguish the colors and those viewing a printed copy or monochrome display. For readers using screen readers, also provide an appropriate text description or accessible data; redundant visual encodings alone may not convey the figure.

For example, instead of relying on red and blue lines alone, use solid and dashed lines and identify each series in the legend. The caption can then explain the series without depending on their colors:

Figure 3. Solid lines show the control group; dashed lines show the treatment group. The color version of this figure is available online.

If the online and print versions are identical, or if color is not relevant to understanding the figure, a note may be unnecessary. Check the journal’s production instructions before adding one automatically.

Common mistakes

• Using vague wording: “See web version” does not say what readers will find there. Say that the figure is available in color online, if that is the difference.
• Using the note instead of a caption: “See online for colors” does not describe the data or explain the figure. Keep the substantive caption.
• Adding a note when nothing changes: If the figure is color in both formats, or there is no meaningful color distinction, the sentence can confuse readers.
• Ignoring required house style: Journals may use terms such as “figure legend” rather than “caption,” or require a specific sentence. Use the journal’s wording when provided.

The safest approach is to check the journal’s instructions, describe the figure clearly, and add one brief sentence identifying the online color version only when readers need that information.