PUP
The Bristol Stool Scale is the most widely used clinical tool for classifying stool. Developed in 1997 by researchers at the Bristol Royal Infirmary, it’s now the standard chart used by doctors, gastroenterologists, and researchers worldwide.
If you’ve ever wondered whether your poop is normal, this scale gives you the answer.
The 7 types
Type 1 — Hard lumps
Separate hard lumps, like nuts. This is the most constipated end of the scale. It means stool has spent too long in the colon and water has been excessively absorbed.
What to do: Drink more water, increase fiber intake, and consider whether medications or stress might be contributing.
Type 2 — Lumpy sausage
A lumpy, sausage-shaped mass with cracks on the surface. Still constipated, but things are moving better than Type 1.
What to do: Same as Type 1 — more water, more fiber, more movement.
Type 3 — Sausage with cracks
A sausage-shaped stool with surface cracks. This is on the low end of normal. Things are working well.
What to do: Keep doing what you’re doing. This is healthy.
Type 4 — Smooth and soft
A smooth, soft sausage or snake. This is the gold standard — the type doctors want to see. Easy to pass, holds its shape, no straining.
What to do: Nothing. This is perfect.
Type 5 — Soft blobs
Soft blobs with clear-cut edges. On the higher end of normal — slightly on the fast side of transit.
What to do: Usually fine. If it’s a sudden change from your normal, pay attention to what you ate.
Type 6 — Fluffy, mushy
Fluffy pieces with ragged edges, mushy. This is on the diarrhea side. Transit is too fast — your colon isn’t absorbing enough water.
What to do: Watch for dehydration. If it persists for more than a few days, consider seeing a doctor.
Type 7 — Watery
Entirely liquid, no solid pieces. This is diarrhea. Your colon is barely absorbing water at all.
What to do: Stay hydrated. If it lasts more than 2 days, or comes with fever, blood, or severe pain, see a doctor.
What’s the healthy zone?
Types 3 and 4 are considered normal and healthy. They indicate good gut transit time — not too fast, not too slow. Your body is absorbing the right amount of water, and your diet is providing enough fiber.
Most people don’t land on the same type every single day. It’s normal to fluctuate between 3 and 5 depending on what you ate, how much water you drank, your stress levels, and your activity.
The concern is when you’re consistently at the extremes — always Type 1–2 (chronic constipation) or always Type 6–7 (chronic diarrhea). That’s when it’s worth talking to a doctor.
Why does it matter?
Your stool type is one of the strongest signals your gut sends. It reflects:
- Transit time — how long food takes to move through your digestive system
- Hydration — how much water your colon is absorbing
- Diet quality — fiber intake, food variety
- Gut microbiome health — the bacteria in your gut influence consistency
- Stress levels — the gut-brain axis is real, and stress directly affects transit
Tracking your Bristol type over time reveals patterns you can’t see from a single log. That’s why apps like PUP use the Bristol Stool Scale as the core of every log — it turns a subjective “today was fine” into data you can actually learn from.
How to use the scale
Look at your stool before you flush. Compare it to the 7 types. Pick the closest match. It doesn’t have to be perfect — even doctors acknowledge that stool can be between types.
If you’re using PUP, it takes about 2 seconds to tap the type. Over a few weeks, you’ll start seeing your distribution: which types you hit most, whether weekdays differ from weekends, and how your diet choices show up in the data.
When to see a doctor
- Persistent Type 1–2 for more than 2 weeks
- Persistent Type 6–7 for more than 3 days
- Blood in your stool
- Unexplained weight loss
- Severe pain during bowel movements
- A sudden, lasting change from your normal pattern
The Bristol Stool Scale isn’t a diagnostic tool on its own — but it gives you and your doctor a shared language to talk about what’s happening.
— The PUP Team
