What Is the Bristol Stool Chart?
The Bristol Stool Chart is a medical classification tool that sorts stool into seven types by shape and consistency. Types 1 and 2 are hard and point to constipation. Types 3 and 4 are the healthy target. Types 5 to 7 get looser towards diarrhoea.
7 Types of Stools on the Bristol Stool Chart
| Type | What it looks like | What it suggests |
| 1 | Separate hard lumps, like nuts. Hard to pass. | Constipation |
| 2 | Lumpy and sausage-shaped. Hard to pass. | Mild constipation |
| 3 | Sausage-shaped with cracks on the surface. | Normal |
| 4 | Smooth and soft, like a snake. | Normal |
| 5 | Soft blobs with clear-cut edges. Passes easily. | Looser end of normal |
| 6 | Mushy pieces with ragged edges. | Mild diarrhoea |
| 7 | Watery with no solid pieces. | Diarrhoea |
What Is Normal on the Bristol Stool Chart?
Types 3 and 4 are the target range. Formed, smooth and passed without straining. Type 5 is mildly loose and still within the usual range. This is where plenty of people land some of the time.
However, form is only half the picture. The other half is frequency, and the normal range is wider than most people assume.
The 3 and 3 rule puts it at three times a day at the top end, down to three times a week at the bottom.
A Swedish study that screened out gut disease, IBS and medication effects found 98% of the remaining group fell inside that range. Almost half of them still strained at times, so the odd difficult day is normal too.
Where you sit most of the time is what counts. Three weeks of type 6 mornings tells you far more than one morning does.
Does Stool Type Show How Fast Your Gut Is Moving?
Stool type reflects transit time, which is how long food takes to move through your gut.
The longer stool sits in your colon, the more water gets drawn out and the harder it becomes. Fast transit leaves more water behind, so stool comes out looser.
The chart comes from a 1997 study at the University of Bristol, which showed stool form is a useful guide to transit time.
That speed is set by peristalsis, the muscle waves that push food along.
Those waves are coordinated by the enteric nervous system in your gut wall, which stays in constant contact with your brain. That's why a stressful week can show up on the chart.
How to Use the Bristol Stool Chart for Gut Health
Log the type each time for a week or two, and note what changed that day. A single entry is noise. A fortnight of entries is information.
- Note the type number, from 1 to 7, each time you go.
- Write down how many times you went that day.
- Add anything that changed, such as a new food or poor sleep.
- Keep going for two weeks.
- Look for your usual type and what moves alongside it.
- Take your notes to your GP if something has changed or worries you.
It can be helpful to log stress alongside the type, since it can affect how fast things move. You can log drinks like Cosmic Hue as well.
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Best sellerFrequently Asked Questions
When Should You Speak to Your GP About Stool Changes?
See a GP if you've had blood in your stool, or a change in its shape or texture, for three weeks. The same goes for a lump or pain in your tummy, or weight loss you can't explain.
For black or dark red stool or bloody diarrhoea, ask for an urgent appointment or call 111. Call 999 if the bleeding won't stop.
Can the Bristol Stool Chart Diagnose a Condition?
No. The Bristol Stool Chart describes form and gives an estimate of transit time. It can show that something has changed, but not why.
A week of type 6 could come from a stomach bug, a stressful stretch or a condition such as IBD, so a GP uses it alongside your symptoms, history and any tests.
What Colour Is Your Stool if You Have IBS?
IBS has no signature colour. It shows up in form and frequency instead, and doctors use the chart to sort IBS into constipation, diarrhoea or mixed types.
Stool type often shifts from day to day with IBS, which is why a fortnight's log tells you more than a single entry. Our IBS guide has the detail.
Who Developed the Bristol Stool Chart?
Dr Stephen Lewis and Dr Ken Heaton developed it at the University of Bristol in 1997. They published it as a practical way to estimate how long food takes to move through the gut.
Conclusion
The Bristol Stool Chart gives you a number for something most people struggle to put into words. A normal stool is types 3 and 4 most days, and anything from three times a day to three times a week counts as normal for frequency.
A single entry tells you almost nothing, so log the type for a couple of weeks and note what else was going on. That's where you can explore patterns.
If you see blood, black or dark red stools, weight loss you can't explain or a bowel habit that has shifted for three weeks, book in with your GP.
References
Lewis, S. J., & Heaton, K. W. (1997). Stool form scale as a useful guide to intestinal transit time. Scandinavian Journal of Gastroenterology, 32(9), 920–924. https://doi.org/10.3109/00365529709011203
NHS. (2023a). Bleeding from the bottom (rectal bleeding). https://www.nhs.uk/symptoms/bleeding-from-the-bottom-rectal-bleeding/
NHS. (2023b). Diarrhoea and vomiting. https://www.nhs.uk/symptoms/diarrhoea-and-vomiting/
Rome Foundation. (2021). Bristol Stool Form Scale [Clinical reference card]. https://theromefoundation.org/wp-content/uploads/Bristol-Stool-Form-Scale-Card-2021.pdf
Walter, S. A., Kjellström, L., Nyhlin, H., Talley, N. J., & Agréus, L. (2010). Assessment of normal bowel habits in the general adult population: The Popcol study. Scandinavian Journal of Gastroenterology, 45(5), 556–566. https://doi.org/10.3109/00365520903551332