About the Bristol Stool Chart: History and Clinical Use
From Bristol Royal Infirmary to global clinical practice - Updated April 2026
The Origin: Bristol Royal Infirmary, 1997
The Bristol Stool Chart - formally the Bristol Stool Form Scale - was developed by Dr Ken Heaton (a reader in medicine) and Dr Stephen Lewis (a research registrar) at the Bristol Royal Infirmary in the late 1990s. The chart was published in 1997 in the Scandinavian Journal of Gastroenterology as: Lewis SJ, Heaton KW (1997). "Stool Form Scale as a Useful Guide to Intestinal Transit Time." Scand J Gastroenterol 32(9):920-4.
The research context was gut transit time. Measuring how long food takes to pass through the digestive system is clinically important but impractical in routine practice - it traditionally required radio-opaque markers or scintigraphy. Heaton and Lewis observed that stool form (shape and consistency) closely correlated with colonic transit time, as measured by these techniques. Their insight was that a simple visual scale - requiring no equipment - could serve as a proxy for transit time assessment.
The original scale was validated in healthy volunteers and patients with gastrointestinal complaints. Participants produced radio-opaque marker shapes visible on X-ray; the time for 80% of markers to pass was correlated with stool form as graded by research staff. Types 1 and 2 corresponded to slow transit (over 72 hours); types 3 and 4 to normal transit (20-40 hours); types 5-7 to fast transit (under 20 hours).
The scale was designed to be simple enough for patient self-report - a key practical advantage over objective transit measurement. This made it applicable far beyond the research setting: in primary care, gastroenterology clinics, care homes, clinical trials, and patient education.
Clinical Use: NHS, NICE, and Rome IV
Since its publication, the Bristol Stool Form Scale has been adopted widely in UK and international clinical practice:
The Rome Foundation's Rome IV criteria (2016), the global standard for functional gastrointestinal disorders, uses Bristol types directly to subclassify IBS. IBS-C requires more than 25% of stools being types 1-2; IBS-D requires more than 25% being types 6-7; IBS-M requires both thresholds. This places the scale at the centre of IBS management worldwide.
NICE guideline CG61 (Irritable bowel syndrome in adults) and various related guidelines reference the Bristol scale for patient assessment and monitoring. NICE's 2008 IBS guidance recommends patients keep a symptom diary that includes stool form as assessed by the Bristol scale.
NHS England published its official Bristol Stool Chart for Carers in 2023 - a large-format, accessible version designed for use in care homes, community nursing, and learning disability settings. This is available as a free PDF from NHS England's website.
The Bristol scale is used as an endpoint in clinical trials for laxatives, antidiarrhoeals, probiotics, and gastrointestinal medications. Its validated, standardised nature makes it suitable for measuring treatment response.
The scale has been translated into over 20 languages and is used by healthcare systems worldwide, including in the United States (where it is commonly called the Bristol Stool Scale), Australia, Japan, Germany, and across Europe. The Cleveland Clinic, Mayo Clinic, Stanford Medicine, and numerous gastroenterology societies all reference it.
About This Site
bristolstoolchart.com is an independent digital health reference project by Digital Signet. It is not affiliated with the NHS, Bristol Royal Infirmary, NICE, the Rome Foundation, Cleveland Clinic, or any other institution or clinical body.
The content of this site has been developed by referencing the original Lewis and Heaton 1997 paper, NHS England guidance, NICE clinical guidelines, and peer-reviewed gastroenterology literature. Content is reviewed against current NHS and NICE guidance before publication.
Our aim is to provide the best freely available consumer reference for the Bristol Stool Chart in the UK - more detailed than the official NHS PDF, more interactive than static reference pages, and written in British English with an NHS-appropriate tone. The interactive stool type selector and the private local-only tracker are the two features that distinguish this site from static references.
We are not doctors. This site does not provide medical advice. If you have a specific clinical concern, please consult your GP.
Updated April 2026