How to Make Figures for PLOS Journals: PLOS figure guidelines

If you are preparing a manuscript for PLOS, your figures need to do two jobs at once. They must communicate the science clearly, and they must satisfy the PLOS figure guidelines before production. That means size, resolution, text legibility, file type, captions, permissions, and ethical presentation all matter. A beautiful figure can still cause delays if it is too small, flattened incorrectly, or missing a scale bar. The good news is that most problems are preventable if you build figures with submission in mind from the start.

This guide walks through the practical requirements authors should check before uploading figures to a PLOS journal. We will cover technical specifications, caption structure, common compliance issues, and a final review workflow you can repeat for every figure.

Start with the official PLOS figure guidelines

The first rule is simple: do not rely on memory. PLOS requirements can vary by journal and may be updated, so always compare your final files against the current author instructions. The official PLOS ONE figure guidance is a useful starting point, and you can review it on the PLOS ONE figures page. If you are submitting to another PLOS journal, check that journal's submission pages too.

Even when the rules look familiar, read the fine print. PLOS separates what a figure should look like in the manuscript from what production needs after acceptance. During initial submission, reviewers need figures that are readable and complete. During production, the journal needs files that reproduce cleanly online and in downloadable formats.

The safest approach is to create production quality figures before first submission. It takes less time than rebuilding every panel after acceptance. It also helps reviewers focus on your results instead of struggling with blurry labels or crowded plots.

Technical specs authors should check first

PLOS figure guidelines are built around readability and faithful reproduction. Your figure should remain clear when displayed at journal column width, downloaded as a file, or viewed on a high resolution screen. Start by setting the final physical size before you export. Do not make a tiny figure and enlarge it later, because that usually reduces quality.

For raster images, resolution matters. Photographs, microscopy images, scans, and heatmaps made of pixels should be exported at sufficient dots per inch for their final print size. A common benchmark is 300 dpi for color or grayscale photographic content. Line art often needs higher resolution because thin lines and text can pixelate quickly. If your figure combines photos, plots, and labels, inspect the exported file at final size.

For vector graphics, preserve vectors whenever possible. Charts, diagrams, forest plots, maps, and schematic illustrations often look best as editable vector artwork. Lines stay sharp, text stays clean, and file sizes can remain manageable. If you export a vector chart as a low quality JPEG, you give up those advantages.

Use standard file formats that PLOS accepts for figure upload and production. Depending on journal and submission stage, this may include TIFF, EPS, PDF, or other common formats. Avoid unusual proprietary formats unless the submission system specifically asks for them. When in doubt, export a high quality TIFF for raster content and a clean PDF or EPS for vector content, then confirm against the journal page.

Size, layout, and panel organization

Many PLOS figure problems start with overcrowding. Authors often try to fit every result into one figure because the story feels connected. Reviewers, however, need space to understand each comparison. If a figure has six panels, each panel still needs readable labels, axis titles, legends, and symbols.

Think in final width. A single column figure needs larger text relative to the artwork than a wide figure. If your labels look acceptable only when zoomed to 200 percent, they are too small. PLOS figure guidelines do not reward cramped design. They reward figures that remain clear in normal reading conditions.

Use panel letters consistently. Place A, B, C, and other labels in the same position across panels. Make them bold enough to find quickly, but not so large that they dominate the data. Refer to those panel letters in the caption and the manuscript text.

Align related panels. If two plots share an x axis or y axis concept, use comparable scales unless there is a strong reason not to. If scales differ, state that clearly. Avoid decorative boxes, heavy shadows, unnecessary gradients, and visual effects that do not add information. PLOS journals publish science, not slide decks.

White space is not wasted space. It separates panels, prevents label collisions, and helps readers move through the figure. A clean figure usually looks calmer because it asks the reader to interpret the data, not the design choices.

Text, fonts, symbols, and line weights

Text inside figures should be boring in the best possible way. Choose simple fonts that render cleanly, such as Arial, Helvetica, or similar sans serif options. Use one font family across all figures unless there is a specific reason to do otherwise. Consistency makes the paper feel more polished and helps production avoid font substitution.

Keep text large enough at final size. Axis titles, tick labels, legends, annotations, and panel labels should be readable without strain. If you must choose between adding another annotation and keeping the graph legible, choose legibility. The caption can carry details that do not need to sit inside the artwork.

Line weights also need attention. Thin lines may disappear after export or compression. Very thick lines can hide data points and error bars. Use line weights that remain visible at the intended figure size. Then export the file and inspect it as a reader would see it.

Symbols should be distinguishable without color alone. Use shape, line pattern, direct labels, or clear legends. This is especially important for accessibility and grayscale printing. If red and green are the only difference between two groups, many readers will struggle.

Color and accessibility in PLOS figure guidelines

Color should clarify the message, not decorate it. PLOS figure guidelines expect figures to be understandable and accurate, and accessible color choices are part of that. Use palettes with strong contrast between groups. Avoid rainbow scales unless you have a defensible reason, because they can create false visual boundaries.

For heatmaps and continuous scales, choose perceptually sensible color maps. Readers should be able to tell whether a value is increasing or decreasing. Include a scale bar or color bar when color encodes quantity. If color identifies categories, include a legend or direct labels.

Also check contrast between text and background. Light gray labels on a white background may look refined on your monitor, but they can vanish on another screen. Black or dark gray text is often the better choice. Scientific clarity beats aesthetic subtlety.

If your figure includes microscopy, gels, blots, or radiology images, apply adjustments consistently. Brightness and contrast changes should not hide, remove, or create features. If you crop an image, do so to focus the reader, not to misrepresent the evidence. Keep original data because journals may request it.

Image integrity, ethics, and data presentation

PLOS journals care about ethical image handling. That is not a box checking exercise. It protects trust in the work. Do not splice image lanes, rearrange fields, remove background artifacts, or selectively enhance areas unless the method is clearly disclosed and scientifically justified.

For microscopy and similar images, include scale bars directly in the image when needed. State the scale in the caption. Do not rely only on magnification, because final figure size can change. A scale bar travels with the image and remains meaningful.

For plots, show data honestly. Use appropriate axes, visible error definitions, and clear sample sizes. Avoid truncated axes that exaggerate effects unless the choice is transparent and justified. If the graph shows mean and error bars, tell readers what the bars represent. Standard deviation, standard error, confidence intervals, and interquartile range are not interchangeable.

When presenting statistical significance, explain symbols in the caption. Do not assume readers know what one, two, or three asterisks mean in your figure. Include exact p values when appropriate, especially if the field expects them. Good figures reduce ambiguity.

Captions that satisfy reviewers and readers

A PLOS figure caption should let the reader understand the figure without hunting through the entire Results section. It does not need to repeat every method, but it should identify what is shown, define abbreviations, explain symbols, and clarify statistical information. Captions are part of the scientific record, not afterthoughts.

Start with a concise title sentence. Tell readers the main content of the figure. Then describe the panels in order. If Figure 2A shows the experimental timeline and Figure 2B shows the primary outcome, say so plainly. Panel by panel structure is easier to follow than a dense paragraph of mixed details.

Define all abbreviations used in the figure, even if they appear elsewhere in the manuscript. Reviewers may look at figures out of order. Readers may download a figure separately. If an abbreviation is important enough to appear in the artwork, it is important enough to define in the caption.

Include statistical details that affect interpretation. State the test used if it is not already obvious from the context, define error bars, provide n values, and explain symbols. If the figure uses normalized values, describe the reference or baseline. If data are pooled, state what was pooled.

Keep captions complete but not bloated. A caption that tries to become a mini methods section becomes hard to read. Put essential interpretation details in the caption and reserve full protocol detail for Methods or supporting information.

File naming, permissions, and supporting information

Name your figure files clearly before upload. Use simple file names such as Figure_1.tif, Figure_2.pdf, or S1_Fig.tif. Avoid spaces, special characters, and vague names like final_final_revised_new.tif. The cleaner your file names, the easier it is to track versions during revision.

If you use third party material, confirm permissions early. PLOS journals publish under open access licenses, so reused images, maps, icons, or adapted diagrams must be compatible with that publication model. A citation alone is not always enough. You may need written permission or a replacement graphic created from your own data.

Supporting information figures should receive the same care as main figures. They may not be in the main narrative, but they still support your claims. Use readable text, complete captions, and appropriate file formats. A weak supporting figure can still raise reviewer concerns.

Pre-submission compliance checklist

Before you upload, run a formal check against the PLOS figure guidelines. Do it after the manuscript and captions are nearly final, because late edits can introduce mismatches. For example, a panel may be removed from the figure but still mentioned in the caption. Or a statistic may change in the Results but not in the legend.

• Open every exported figure file, not just the editable source file.
• View each figure at its expected final size and at 100 percent zoom.
• Confirm that all panel labels match the caption and manuscript text.
• Check that axis labels, units, legends, and scale bars are present.
• Verify that abbreviations are defined in the caption.
• Confirm that color is not the only way to distinguish key groups.
• Check image resolution, file format, and file naming.
• Review image adjustments for ethical and consistent handling.
• Confirm that third party material has suitable permissions.
• Make sure supporting information figures follow the same standards.

This checklist may feel repetitive, but it catches the small problems that slow submission. It is much easier to fix a missing unit before upload than after a reviewer questions the figure's meaning.

How Graffiy can help you prepare PLOS-ready figures

Many figure issues come from switching between tools, exporting multiple times, and losing track of size or style settings. Graffiy is built to help researchers create cleaner scientific visuals with less manual formatting. You can create with Graffiy when you need polished figures, graphical summaries, or educational visuals that still respect scientific clarity.

We still recommend checking the official journal instructions before submission. No design platform should replace the author guidelines. But a structured figure workflow can reduce avoidable errors. It can also help your team keep fonts, colors, panel spacing, and visual style consistent across the full manuscript.

One practical habit is to create a figure style sheet for the paper. Note the font, label size, line weights, color palette, panel label style, and preferred export formats. Use that style sheet for every figure. Consistency makes the paper easier to read and easier to revise.

Final thoughts before submission

The best figures for PLOS are clear, honest, and technically ready. They do not need visual tricks. They need readable labels, appropriate resolution, accurate captions, accessible color, and careful compliance checks. If you follow the PLOS figure guidelines from the first draft of each figure, the final submission process becomes much less stressful.

Do not wait until the upload screen to think about figure quality. Build figures at final size, preserve clean source files, export properly, and review captions beside the artwork. That simple discipline can prevent delays and make your results easier to understand.

Figures are often the first part of a paper that reviewers study closely. Treat them as scientific arguments, not decorations. When your visuals are precise and compliant, you give your manuscript a better chance to be read on its merits.