This page is for education only and is not a medical diagnosis. If you notice blood, black/tarry stool, or persistent changes in your bowel habits, contact a doctor.
The Bristol Stool Chart (also called the Bristol Stool Form Scale, or BSFS) is a medical classification tool created by Lewis & Heaton in 1997 to describe the shape and consistency of human stool. It splits stool into 7 types, from hard separate lumps (Type 1) to entirely liquid (Type 7). Because stool form correlates closely with how long it spent in your colon — confirmed in later transit-time studies — it's one of the simplest ways to get a read on your digestive health at a glance. It's also the foundation of PooDoo's Digestive Health Score.
| Type | Look | General meaning |
|---|---|---|
| 1 | Separate hard lumps | Severe constipation / dehydration |
| 2 | Lumpy sausage | Mild constipation / slow transit |
| 3 | Sausage with cracked surface | Normal — near ideal |
| 4 | Smooth soft sausage | Normal — the "gold standard" |
| 5 | Soft blobs, clear edges | Lacking fiber / fast transit |
| 6 | Fluffy, ragged edges | Mild diarrhea / irritation |
| 7 | Watery, no solid pieces | Diarrhea — needs attention |
Type 1 – Separate Hard Lumps (Severe Dehydration)
Hard, disconnected lumps that look like nuts and are difficult and often painful to pass. This is the far constipated end of the scale — stool has spent so long in the colon that almost all water has been reabsorbed from it.
What it usually means: Low fiber intake, low fluid intake, or a slow-moving gut (sometimes from low activity, some medications, or stress). Straining regularly at this stage can contribute to hemorrhoids over time.
What helps: Gradually increasing water and fiber (fruit, vegetables, whole grains) and daily movement. If it's persistent or painful, it's worth a conversation with a doctor.
Track your hydration & log Type 1 days in PooDoo →Type 2 – Lumpy Sausage (Slow Transit)
A sausage shape made of compacted lumps. Still firmly on the constipated side, but less severe than Type 1 — stool is holding together in one piece rather than separate lumps.
What it usually means: Similar drivers to Type 1 — often diet, hydration, or a temporarily slower gut — just earlier in that pattern.
What helps: Same as Type 1: more water, more fiber, regular movement. Tracking how often Type 1–2 days show up helps you (and a doctor, if needed) tell a one-off from a pattern.
See your weekly trend in PooDoo →Type 3 – Sausage with Cracked Surface (Near Ideal)
A sausage shape with visible cracks on the surface. This sits right at the healthy end of the scale, alongside Type 4.
What it usually means: Good hydration and fiber balance, and healthy transit time — generally nothing to change.
Log the good days too — patterns matter →Type 4 – Smooth Soft Sausage (Golden Standard)
A smooth, soft, sausage or snake shape. Clinically, this is considered the ideal — easy to pass, well-formed, and a sign of a well-balanced gut.
What it usually means: Your fiber, fluid, and gut transit time are all in a good range. This is the target PooDoo's Digestive Health Score treats as "no deduction."
See how consistently you hit Type 4 →Type 5 – Soft Blobs with Clear Edges (Fast Transit)
Soft blobs with well-defined edges, passed easily. Slightly on the loose side of normal.
What it usually means: Often diet-related — lower fiber relative to fluid, or a slightly faster transit time. Occasional Type 5 is common and not a concern on its own.
What helps: If it's frequent, adding more soluble fiber (oats, bananas, psyllium) can help firm things up.
Spot what triggers Type 5 days →Type 6 – Fluffy Pieces with Ragged Edges (Irritated Gut)
Mushy, fluffy pieces with ragged edges — mild diarrhea. Stool moved through the colon faster than usual, so less water was reabsorbed.
What it usually means: Can follow spicy or high-fat meals, stress, mild bugs, or sensitivities (including FODMAPs). If it's a one-off, it's rarely a concern.
What helps: Bland foods, hydration with electrolytes, and noting what you ate beforehand. See a doctor if it lasts more than 2 days or comes with fever or pain.
Log symptoms & possible triggers in PooDoo →Type 7 – Watery, No Solid Pieces (Emergency)
Entirely liquid, with no solid pieces — true diarrhea. Transit time was very fast and almost no water was reabsorbed.
What it usually means: Infection, food poisoning, a flare of an underlying condition, or a strong reaction to something eaten. This is also the stage where dehydration becomes a real risk.
What helps: Prioritize fluids and electrolytes. If it lasts more than 24–48 hours, includes blood, black/tarry stool, or severe pain, seek medical care promptly — this is one of the cases PooDoo's methodology flags for an immediate "consult a physician" recommendation.
Track frequency so you know when it's time to call a doctor →Curious what your stool's color means too?
Shape is only half the picture. See the Stool Color Guide for what brown, pale, black, and red can indicate, or read the full scoring methodology.