Bristol Stool Chart & Transit Calculator
Select your stool form, color, and urgency level to calculate estimated colonic transit speed and evaluate potential motility patterns.
Tap the visual form that closest matches your most recent bowel movement.
Stool color reflects bile metabolism, transit speed, and gastrointestinal bleeding.
Incomplete evacuation sensation (Tenesmus)
Did it feel like stool remained trapped in the rectum after evacuation?
Classification
Optimal Form
Colonic transit time
30 to 40 hours
Transit category
Normal Transit
What this indicates: Smooth, soft, and passes effortlessly in one piece. Clinical gold standard.
Colonic transit velocity determines stool moisture content. In healthy individuals, food residue remains in the large intestine for 30 to 45 hours, forming smooth Bristol Type 4 stool. When transit exceeds 60 hours, the colon absorbs excess moisture, producing dense, hard lumps. When transit drops below 20 hours, rapid peristalsis prevents water reabsorption, resulting in loose stool.
One stool entry is not a diagnosis
Gastroenterologists diagnose IBS and motility disorders based on 30-day distributions, variance penalties, and food lag correlations. GutLog tracks this on your iPhone in 30 seconds a day.
Clinical context and interpretation
What does colonic transit time mean?
Colonic transit time is the duration required for digested food residue to pass through the large intestine. As stool moves through the colon, water is reabsorbed. Slow transit allows excessive water reabsorption, creating hard Type 1 or 2 stools. Fast transit prevents adequate reabsorption, resulting in loose Type 6 or 7 stools.
How is this information used to diagnose IBS?
Under the Rome IV diagnostic criteria, gastroenterologists evaluate the percentage of days your bowel movements fall into constipation (Types 1–2) versus diarrhea (Types 5–7). If both patterns occur more than 25% of the time, the condition is classified as mixed-type IBS (IBS-M).
When should stool changes prompt emergency care?
Seek prompt medical care if you observe black or tarry stools, persistent bright red rectal bleeding, unintended weight loss, fever with bowel movements, or bowel movements that wake you from sleep.
Track your Bristol Stool distribution in GutLog
Record entries in under 30 seconds on iPhone. Measure your Gut Health Score, detect food lag correlations, and export doctor-ready A4 reports.
Download on the App Store