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Free CONSORT Flow Diagram Generator for Randomized Controlled Trials

Generate the official CONSORT flow diagram for your parallel-group or multi-arm RCT. Supports 2, 3, or 4 allocation arms. Counts auto-calculate, exports at 300/600 dpi. Fully editable PowerPoint. No data leaves your browser.

In Simple Words: Every randomised controlled trial published in a clinical journal must include a CONSORT flow diagram showing how many participants were assessed for eligibility, randomised, allocated to each arm, followed up, and analysed. CONSORT compliance is checked at peer review: incomplete flow diagrams are one of the most common reasons for revision requests in trial reports.

This tool generates the diagram for 2-arm trials and expands to 3 or 4 arms when you name additional allocation groups. Every Enrolment count auto-calculates from your screening and exclusion numbers. Per-arm boxes update from the allocation and analysis fields you enter.

When to Use the CONSORT Flow Diagram

Use CONSORT whenever your study is a randomised controlled trial: parallel-group, crossover, cluster, or factorial design. CONSORT 2025, published in April 2025, is the current version and replaces CONSORT 2010. Its flow diagram keeps the four stages (Enrolment, Allocation, Follow-Up, Analysis) and reports, for each group, participants lost to follow-up and analysed for the primary outcome. This generator follows the CONSORT 2025 flow diagram.

Do not use CONSORT for observational studies: those require STROBE. For trial statistical analysis, see the t-test calculator, sample size calculator, or the Test Selector.

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Worked Examples

Example 1: Two-arm drug vs placebo RCT

A trial of a new antidiabetic agent assessed 720 patients. 220 excluded (140 ineligible, 80 declined). 500 randomised. Intervention arm: 250 allocated, 240 received (10 did not), 12 lost to follow-up, 5 discontinued the intervention but stayed in follow-up, 238 analysed (the 10 who did not receive it and the 5 who discontinued stay in the intention-to-treat analysis). Placebo arm: 250 allocated, 248 received (2 did not), 10 lost, 3 discontinued, 240 analysed. The diagram calculates analysed as allocated minus lost to follow-up minus excluded from analysis (250 minus 12 = 238; 250 minus 10 = 240). Discontinued participants are reported in the follow-up box but are not subtracted, as in CONSORT 2025. Enter these numbers: the diagram auto-populates all four stages for both arms.

Example 2: Three-arm dose-finding trial

360 patients randomised equally to Low Dose, High Dose, and Placebo (120 per arm). Type “Placebo” in the Arm 3 name field: the diagram expands from two columns to three automatically. Each arm’s allocation, follow-up, and analysis counts are entered separately in the expanding form.

Assumptions and Requirements

  • All randomised participants must be accounted for. Those who never received treatment or did not complete follow-up still appear, in “Did not receive allocated intervention” or “Lost to follow-up for primary outcome.” CONSORT permits no disappearing participants.
  • Analysed counts must match your primary analysis population. State in Methods whether you used intention-to-treat or per-protocol, and the analysed count must match exactly.
  • Exclusion reasons must be itemised separately. The CONSORT 2025 flow diagram lists not meeting inclusion criteria, declined to participate and other reasons as separate exclusion categories, not merged.

Common Mistakes

  • Missing randomised participants. Every randomised participant must appear in the diagram: omissions are the most common CONSORT violation flagged at review.
  • Confusing excluded with ineligible. Did-not-meet-criteria and declined-participation are different populations and must be reported separately.
  • Using an ITT count that quietly excludes participants. A true ITT analysis includes all randomised participants. Exclusions from the analysis must be visible and justified in the diagram.
  • Omitting the diagram for crossover trials. Crossover RCTs still require a CONSORT flow for the enrolment and allocation stages: many authors omit it incorrectly.

Frequently Asked Questions

CONSORT 2010 or CONSORT 2025?
Use CONSORT 2025 (April 2025), which replaces CONSORT 2010. It keeps the four-stage flow structure and labels the later boxes by the primary outcome: lost to follow-up for primary outcome, discontinued intervention, analysed for primary outcome. Participant flow is checklist item 22: 22a gives the numbers randomised, receiving the intended intervention and analysed for the primary outcome; 22b gives losses and exclusions after randomisation, with reasons. Some journals may still name CONSORT 2010 in their author instructions: check your target journal before choosing which version to cite.
Where do protocol deviations go?
Deviations affecting intervention receipt go in “Did not receive allocated intervention.” Those affecting follow-up go in “Lost to follow-up for primary outcome.” Those affecting analysis eligibility appear in “Excluded from analysis” within the Analysed box. Participants who stop the intervention but stay in follow-up are counted under Discontinued intervention and remain in the analysis unless excluded.
What format for JAMA or NEJM submission?
Use PNG at 600 dpi, 85 mm width: this meets JAMA, NEJM, BMJ, and Lancet figure specifications. The PowerPoint export gives editable native shapes if the editorial office requests adjustments.
Is CONSORT required for pilot and feasibility trials?
Yes, CONSORT for Pilot and Feasibility Trials (2016) recommends the same flow structure. Documenting recruitment performance is typically the primary outcome of a feasibility study, making the flow diagram especially important.

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References

  1. Hopewell S, Chan A-W, Collins GS, et al. CONSORT 2025 statement: updated guideline for reporting randomised trials. BMJ. 2025;389:e081123. PMID 40228833.
  2. Moher D, Hopewell S, Schulz KF, et al. CONSORT 2010 explanation and elaboration: updated guidelines for reporting parallel group randomised trials. Int J Surg. 2012;10:28–55. PMID 22036893.
  3. Altman DG, Moher D, Schulz KF. Improving the reporting of randomised trials: the CONSORT Statement and beyond. Stat Med. 2012;31:2985–2997.

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