BMJ Open Formatting Requirements: Complete Author Guide

BMJ Open publishes several article types with distinct word limits. The editorial system checks these during submission.

Word counts exclude the abstract, references, figure legends, and table content. BMJ Open doesn't impose a strict limit on figures, tables, or references, which is more generous than most journals. That said, don't go overboard. If your paper has 15 figures, consider moving some to the supplementary file.

Protocol papers are a distinctive feature of BMJ Open. Publishing your study protocol before collecting data provides a citable record of your planned methods, helps prevent outcome reporting bias, and can count as a publication. BMJ Open is one of the most popular venues for protocol publication.

BMJ Open requires structured abstracts for all research articles, limited to 300 words. The required headings are:

For Original Research:

• Objectives
• Design
• Setting
• Participants
• Interventions (if applicable)
• Primary and secondary outcome measures
• Results
• Conclusions

This is more granular than most journals. Where other journals combine design information into a single "Methods" heading, BMJ Open separates Design, Setting, Participants, and Interventions into individual sections. Each should be 1-2 sentences.

Objectives should state exactly what the study aimed to do. One sentence is usually enough.

Design specifies the study type: randomized controlled trial, prospective cohort, cross-sectional survey, etc. Include the time period.

Setting describes where the study was conducted: primary care, hospital, community, country.

Participants includes the number enrolled, key demographics, and inclusion criteria.

Results should report primary outcomes with numbers, effect sizes, confidence intervals, and P values. Be specific.

Conclusions should be limited to what the data support. BMJ Open reviewers are particularly attentive to conclusions that overreach the data, and the open review process means any reviewer criticism of your conclusions will be publicly visible.

BMJ Open requires a "Strengths and Limitations" box immediately after the abstract. This must contain 3-5 bullet points that honestly assess your study's strengths and limitations.

This is unusual. Most journals ask authors to discuss limitations in the Discussion section, but BMJ Open puts them front and center. Don't treat this as a throwaway. Reviewers compare your self-assessment against their own evaluation, and a paper that omits obvious limitations will draw criticism in the open review.

Good Strengths and Limitations statements are specific. "Large sample size" is vague. "Population-based cohort of 45,000 participants with 10 years of follow-up" is informative. Similarly, "potential for confounding" is generic. "Unable to adjust for socioeconomic status due to data limitations" is honest and specific.

BMJ Open requires a title page with:

• Full title (informative and specific)
• All author names with highest academic degrees
• Institutional affiliations
• Corresponding author's contact details
• Word count of body text and abstract (separately)
• Number of figures and tables
• Keywords (3-5 from MeSH terms)

BMJ Open also requires:

• Contributor statement: specific contributions for each author using ICMJE criteria
• Funding statement: all funding sources and grant numbers
• Competing interests declaration: must be completed for all authors
• Patient and public involvement statement: describe how patients/public were involved in the research design, conduct, or dissemination (or state that there was no involvement)

The Patient and Public Involvement (PPI) statement is a BMJ Group-wide requirement and is taken seriously. If patients weren't involved in your study design, say so directly. Don't fabricate involvement.

BMJ Open doesn't impose a strict limit on the number of figures and tables. However, the expectation is that display items should be necessary and well-designed.

Figure requirements:

• Minimum resolution: 300 DPI for photographs, 600 DPI for line art
• Accepted formats: TIFF, EPS, JPEG, or PDF
• Maximum file size: 5 MB per figure (larger files can be uploaded as supplementary)
• Color figures are free (open access journal)
• Each figure uploaded as a separate file during submission
• Multipanel figures should be clearly labeled (A, B, C)

Table requirements:

• Created in Word using the table editor
• Every column must have a header
• Use horizontal rules only (top, bottom, below headers)
• No vertical lines or cell shading
• Footnotes use superscript symbols or lowercase letters
• All abbreviations defined below the table
• Tables placed at the end of the manuscript, each on a separate page

For systematic reviews, PRISMA flow diagrams are expected as Figure 1. Forest plots should include heterogeneity statistics (I-squared, chi-squared P value) and individual study weights.

BMJ Open uses standard Vancouver (NLM) reference formatting. References are numbered consecutively as they appear in the text and cited using superscript numbers.

Key formatting rules:

• Superscript citation numbers in text, placed after punctuation
• List all authors up to 6; for 7 or more, list the first 6 followed by "et al"
• Journal titles abbreviated per NLM/Medline standards
• Include volume, page range (or article number for e-publications), and year
• DOIs encouraged for all references
• Include PMIDs where available

Example reference:

1 Smith AB, Jones CD, Williams EF, et al. Patient engagement in primary care quality improvement: a cluster randomized trial. BMJ Open 2025;15:e098765. doi:10.1136/bmjopen-2025-098765

Note that BMJ Open uses "e" article numbers rather than page ranges for its own articles. When citing other BMJ Open papers, use the article number format.

Reference managers with BMJ-specific styles are available from BMJ Author Hub. Both Zotero and EndNote have compatible output styles. Verify your style is set to Vancouver format before exporting.

BMJ Open publishes supplementary material online alongside the article. All supplementary files undergo peer review.

Supplementary material can include:

• Additional tables and figures
• Extended methods and statistical analyses
• Questionnaires and survey instruments
• Interview topic guides (for qualitative research)
• Data collection forms
• Additional sensitivity analyses

Supplementary files are labeled as "online supplemental file 1," "online supplemental figure 1," etc. They can be submitted as Word, PDF, Excel, or other standard formats.

For systematic reviews, the full search strategy for each database should be included as supplementary material. For qualitative studies, the interview guide or focus group schedule should also be supplementary.

BMJ Open prefers Microsoft Word for submissions. The journal uses ScholarOne, and the production workflow is built around Word and XML.

Word submissions:

• 12-point Times New Roman or Arial
• Double-spaced throughout
• Continuous line numbering (this is mandatory, not optional)
• 1-inch margins on all sides
• Page numbers on every page

LaTeX submissions:

• Accepted but not the standard workflow
• Submit compiled PDF plus all source files
• Use a standard article class (no BMJ-specific template is provided)
• Will be converted to Word/XML during production
• Expect some formatting adjustments during copyediting

For most BMJ Open submissions (clinical trials, observational studies, public health research), Word is the practical choice. LaTeX offers no meaningful advantage for the types of manuscripts BMJ Open typically publishes.

BMJ Open's open peer review policy means:

• Reviewer names are published alongside accepted articles
• The full review history (reviewer reports, editor decisions, author response letters) is published online
• Reviewers know their identity will be revealed if the paper is accepted
• Authors should write response letters knowing they will be public

This has practical implications for formatting. Your response to reviewers should be professional, detailed, and well-organized. Use a point-by-point format addressing each comment. These responses become part of the permanent published record.

BMJ Open has several unique requirements beyond the standard formatting rules.

1. EQUATOR checklists are non-negotiable. This is the single most common reason for desk rejection at BMJ Open. If you don't upload the right checklist, your paper won't enter review. Period.

2. Strengths and Limitations box is mandatory. This appears immediately after the abstract and is separate from the Discussion section. It must contain 3-5 bullet points.

3. Patient and Public Involvement statement is required. Even if patients weren't involved, you must include a statement. This is increasingly common across BMJ journals.

4. Open review changes the dynamic. Knowing that reviews will be published tends to produce more constructive and thorough reviews. But it also means your response letters need to be polished. Typos and terse responses will be permanently visible.

5. Protocol papers are a strong option. If you're planning a clinical trial or systematic review, consider submitting the protocol to BMJ Open before starting data collection. This establishes your methods publicly and can prevent accusations of outcome switching.

The most frequent triggers for administrative return at BMJ Open:

• Missing EQUATOR checklist (most common reason by far)
• Missing Strengths and Limitations box
• Abstract exceeding 300 words
• Missing Patient and Public Involvement statement
• Abstract using wrong headings (e.g., "Methods" instead of "Design")
• Checklist page numbers that don't match the manuscript
• No line numbering in the manuscript