Bristol Stool Scale Check
Use stool form and color as signals, not a self-diagnosis
- Difficulty
- Starter
- Time to result
- ~days to results
- Steps
- 4
- Confidence
- 96%
The Bristol Stool Scale classifies stool from type one, separate hard pellets, through type seven, liquid stool. Bulsiewicz describes types one and two as constipation forms, six and seven as diarrhea forms, and three to five as the preferred general range, with four as the idealized soft, smooth, formed stool. Form partly reflects transit: longer time in the colon allows more water removal, while rapid transit leaves more water. Color adds separate clues but not diagnoses. The episode says visible blood is not normal and is grounds to talk to a doctor; black tar-like, foul-smelling stool may indicate upper gastrointestinal bleeding, while white or fatty yellow stool can have other concerning causes. Food and medicines can also change color, so context and clinical assessment matter.
Origin
The scale arose from a Bristol study in the 1990s. Bulsiewicz uses it alongside newer Zoe survey and transit research to explain stool form and warning signs.
Core principles
- 01Stool form can provide a basic signal about bowel transit
- 02Types three to five are generally the target range described in the episode
- 03Form and color cannot establish a diagnosis
- 04Visible blood warrants medical discussion rather than assumption
How to run it
- 1
Classify the form
Compare the stool with the seven Bristol forms, from hard separate pellets to liquid. Use the number as descriptive language, not a diagnosis.
Pro tip Record repeated patterns rather than overreacting to one isolated bowel movement.
Watch out A chart cannot determine the cause of a symptom.
- 2
Locate the general range
Types three, four, and five are the general range Bulsiewicz describes as desirable, with four idealized. Types one and two align with constipation; six and seven align with diarrhea.
Pro tip Use the type number when describing symptoms to a clinician.
Watch out Being outside the target range does not by itself establish a disease.
- 3
Add color and context
Notice color, recent foods, and medicines. The episode notes that beets can redden stool, blueberries or dye can make it blue, and bismuth can make it black.
Pro tip Note timing after foods or medicines when speaking with a clinician.
Watch out Do not assume red stool is hemorrhoids or black stool is only medication.
- 4
Escalate warning signs
Discuss visible blood with a doctor. Concerning black tar-like stool, white stool, or oily yellow stool also merits professional assessment because the episode links these appearances with possible bleeding, bile blockage, or impaired fat digestion.
Watch out This framework does not provide emergency triage; seek urgent care when symptoms are severe or accompanied by other alarming signs.
In the wild
A person notices repeated hard pellet-like stools and records them as Bristol type one. Instead of trying to diagnose the cause, they use the shared term and the duration of the change when speaking with a clinician.
→ The observation becomes clearer clinical information without pretending the chart identifies a disease.
Common mistakes
Self-diagnosing from form alone
The scale describes appearance and offers signals; it does not identify the underlying cause by itself.
Assuming blood is hemorrhoids
Bulsiewicz explicitly warns against that assumption and encourages medical assessment.
Ignoring food or medicine context
Beets, blueberries, food dye, and bismuth are among the non-disease explanations discussed for color changes.
Is it for you?
Best for
Adults who want to describe stool form more clearly and recognize the warning signs discussed in the episode.
Not ideal for
Anyone seeking to rule out disease or replace professional evaluation with a visual chart.
From the transcript
“we want to be somewhere on the spectrum of three, four, or five.”
“if you see blood in your stool, that's not normal.”
“I would encourage people to get checked out”
From the episode
The Poo Scientist: "If Your Poo Looks Like This Go To A Doctor!", "Your Gut Health Causes Belly Fat, Anxiety!" & "Alcohol Is Destroying Your Gut Microbiome!"