How to Write Figure Legends

Why figure legends matter

Figures draw a lot of attention during peer review. However strong the visual, if the legend is weak, readers may not fully understand what they are looking at. That reduces the impact of your message and hurts the professional look of the manuscript.

A good figure legend:

• Makes the figure understandable without the main text.
• Reduces misinterpretation of the data.
• Explains panels, symbols, abbreviations, and scales.
• Helps reviewers and editors evaluate figures faster.
• Raises the overall writing quality of the paper.

What is a figure legend?

A figure legend is the explanatory text below a figure, graph, image, micrograph, flowchart, or photograph in a manuscript. Its purpose is to give readers the essential information they need to understand that visual.

A strong legend should:

• State what the figure shows
• Describe panel structure when present
• Provide key methodological context
• Define abbreviations, markers, and symbols
• Include statistical information when needed

What belongs in a figure legend?

Not every paper needs the same level of detail, but strong legends usually include:

1. Figure number and short title

The legend typically starts with “Figure 1.” or “Fig. 2” followed by a brief phrase that reflects the main message.

Example: Figure 2. Key anatomical landmarks during endoscopic third ventriculostomy.

2. What the figure shows

Readers should grasp the content in the opening sentence—clearly, without unnecessary length.

Example: This figure shows changes in cell viability in control and treatment groups.

3. Panel descriptions

Multi-panel figures (A, B, C, etc.) should define each panel separately.

Example: (A) Preoperative MRI. (B) Early postoperative control MRI. (C) Graph of lesion volume change.

4. Methods or experimental conditions

Include only the technical details needed to interpret the figure—not a full Methods section.

Example: Cells were incubated with 10 µM drug for 24 h.

5. Abbreviations, symbols, and markers

Define abbreviations at first use. Explain asterisks, arrows, color codes, and custom symbols.

Example: ETV: endoscopic third ventriculostomy. *: P < 0.05, **: P < 0.01.

6. Scale and magnification

Essential for micrographs, radiology images, and macroscopic photos.

Example: Scale bar = 50 µm.

7. Statistical information

For graphs and quantitative visuals, state how data are presented and how groups were compared.

Example: Data are mean ± SEM. Groups were compared by one-way ANOVA.

How to write a figure legend step by step

Use clear, purposeful language rather than complex prose. Build the legend systematically:

1. Identify the main message. What should the reader take away? If that is unclear, the legend will feel scattered.
2. Describe the figure in general. Summarize the overall content in the first sentence.
3. Explain panels or sub-panels. Readers should know what each lettered panel shows.
4. Add essential technical details. Only as much as needed—the legend is not the Methods section.
5. Define abbreviations and symbols. Readers should not have to guess.
6. Final check. Can someone understand the figure from the legend alone, without the main text?

Click to enlarge

Weak vs strong legend examples

Weak example

Figure 3. Cell viability results.

Too short—no context. Which cells? Which groups? Which assay? Which time points? Unknown.

Stronger example

Figure 3. Comparison of cell viability in control and treatment groups. Cells were treated with 10 µM drug for 24, 48, and 72 h. Viability was assessed by MTT assay; data are mean ± SEM (n = 3). *P < 0.05, **P < 0.01 vs control.

This version is far more informative and makes the figure easier to interpret.

Common mistakes

• Being too vague — phrases like “Results are shown” add little.
• Repeating only the figure title — the legend should add information.
• Overloading with methods — do not replace the Methods section.
• Leaving abbreviations undefined — especially problematic for readers outside your subspecialty.
• Skipping panel labels — explain what A, B, C each show.
• Undefined statistical markers — asterisks, error bars, and n values must be clear.

Practical writing tips

• Draft the legend after the figure is finalized.
• Keep it short but complete.
• State the main message in the first sentence.
• Describe panels in order.
• Do not redundantly repeat information already obvious on the figure.
• Check the journal's author guidelines.
• Define technical abbreviations at first use.

Quick checklist before submission

• Can the figure be understood from the legend alone?
• Are all panel labels explained?
• Are abbreviations and symbols defined?
• Is scale bar or magnification information included?
• Are statistical details included where needed?
• Is the legend concise, clear, and readable?
• Does it follow the journal's style?

Frequently asked questions

Is a figure legend the same as a figure title?

No. The title is shorter and headline-like. The legend is the fuller explanatory text below the figure.

How long should a legend be?

There is no single ideal length. Aim for as long as necessary and as short as possible—without vague shortcuts or method overload.

Must every abbreviation be defined?

Apart from a few universally understood terms in your field, defining abbreviations used in the legend is good practice.

Should statistics go in the legend?

For graphs and quantitative figures, usually yes—at minimum data presentation, sample size, and significance markers.

In short

A good figure legend is a small but vital part of scientific communication.

A strong figure catches attention; a strong legend ensures it is understood correctly.

• Be clear
• Be concise but complete
• Make the figure stand alone
• Explain abbreviations, symbols, and panels
• Include statistics and technical details when needed

For broader manuscript structure, see our how to write a scientific paper guide—for reporting analyses, see how to write the statistical analysis section.