The Bristol Stool Form Scale is the most widely used clinical reference for describing stool form, sorting bowel movements into seven types. Here is what each type means and why it matters.
What the Bristol Stool Scale is
The Bristol Stool Form Scale describes stool across seven types, running from firm and separate to entirely liquid:
Type 1 — separate hard lumps, like nuts, and hard to pass
Type 2 — lumpy and sausage-shaped
Type 3 — sausage-shaped with cracks on the surface
Type 4 — smooth and soft, like a sausage or snake
Type 5 — soft blobs with clear-cut edges
Type 6 — fluffy, mushy pieces with ragged edges
Type 7 — watery, with no solid pieces
Why clinicians use it
The scale was developed at the University of Bristol and has become the standard reference for stool form in both clinical practice and research.[1] Gastroenterologists use it to assess bowel health, guide IBS evaluation, monitor treatment response, and gauge transit time. Its value is that form reliably reflects transit time — how long stool spends in the colon.
Types 1 and 2 indicate slow transit, where the colon has reabsorbed more water (commonly described as constipation). Types 6 and 7 indicate fast transit, where there was less time to absorb water (diarrhea). Types 3 and 4 sit in the middle and are widely considered the ideal: comfortable to pass, with balanced transit.
How Throne uses it
Throne classifies each bowel movement into one of the seven types automatically, with nothing to log or photograph. This removes the scale's main limitation in everyday use — its reliance on people to notice, remember, and correctly record their own stool form, which is markedly less reliable than expert assessment.[2]
Because Throne captures every session consistently and objectively, it can show how often each type appears and how that distribution changes month to month — a level of detail that recall alone can't provide.
How to read it
The Bristol view counts each type across three 30-day windows. A drift toward the Types 3 and 4 center over time generally indicates a move toward the typical range, while clustering at the ends reflects firmer or looser stools.
As with every Throne metric, the trend against an individual baseline is more informative than any single entry.
For more background, read The Ultimate Guide to Poop.
References
Lewis SJ, Heaton KW. Stool form scale as a useful guide to intestinal transit time. Scand J Gastroenterol. 1997;32(9):920–924.
Blake MR, Raker JM, Whelan K. Validity and reliability of the Bristol Stool Form Scale in healthy adults and patients with diarrhoea-predominant irritable bowel syndrome. Aliment Pharmacol Ther. 2016;44(7):693–703.
This content is for informational purposes only and is not intended as medical advice. Throne is a general wellness product, not a medical device, and is not intended to diagnose, treat, cure, or prevent any disease. Consult your physician with any health-related questions.
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