For each bowel movement, note the date and time, choose the Bristol Stool Form Scale number from 1 to 7 that looks closest, and add a short note only about what else was different, such as straining, urgency or pain. Treat the number as a description of stool form, not a score of how well your gut is doing. It makes entries easier to compare with meals and other symptoms, but it cannot say why a stool looked the way it did.
What the scale describes
The Bristol Stool Form Scale is a seven-point chart of stool appearance. The Bladder and Bowel Community’s version runs from type 1, “separate hard lumps, like nuts (hard to pass)”, through type 4, “like a sausage or snake, smooth and soft”, to type 7, “watery, no solid pieces, entirely liquid”.
Its job in a diary is to give you a consistent word or number for something that is awkward to describe. NICE’s irritable bowel syndrome (IBS) guideline makes the same point for clinicians: when establishing bowel habit, showing people the Bristol Stool Form Scale may help them with description, particularly for the quality and quantity of stool.
It does not tell you whether a number is good or bad for you. Whether a change matters depends on what is usual for you, how long it lasts and what else is happening, which is a conversation for a clinician rather than something a diary can settle.
A simple bowel entry
A manageable entry has three parts:
- When: the date and approximate time.
- What it looked like: the scale number, or a few plain words if no number fits.
- Anything that stood out: only if it applied, for example straining, urgency, pain, a feeling that you had not finished, or leakage.
An NHS physiotherapy bowel habit diary used by University Hospitals Dorset (version dated February 2022) is a useful example of how much a clinical form may ask. It records date and time, stool type, leakage, time on the toilet, straining, pain or bleeding, laxative or anti-diarrhoea medicine, and more. That diary is designed for people being assessed for bowel problems, so you do not need to copy all of it. Its instruction to “fill in the form to the best of your ability but don’t worry if you can’t complete it every time” is a good one to keep.
For a food-and-symptom diary, a short line such as “07:40, type 5, urgent” is usually enough. If you take a laxative or anti-diarrhoea medicine, you can note that it happened as part of the day’s record; do not change a medicine because of a diary entry, and raise questions about medicines with a pharmacist or doctor.
Record what you see, not what you expect
Choose the number when you notice, rather than reconstructing it at the end of the day. If a movement was between two types, write both, such as “3–4”, instead of rounding towards the number you expected. If you did not look, write “not checked” rather than leaving a gap that could later be read as “normal”.
Keep uneventful days in the record. A day with one ordinary movement and no symptoms is a comparison point, and so is a day when you did not open your bowels. A blank entry could mean either “nothing happened” or “I forgot”, so use a clear “none” when that is what occurred, and keep missing check-ins distinct from days that were recorded as uneventful.
How far to trust the number
The scale is widely used, but it is a self-reported judgement of appearance, and people do not always classify the same stool in the same way.
A 2016 UK study by Blake and colleagues tested it with 169 healthy volunteers who classified their own stool samples, 86 who classified stool models, and 19 people with diarrhoea-predominant IBS. Volunteers’ classifications correlated moderately with measured stool water content (Spearman’s rho 0.491). Of the stool models, 81% were classified correctly, with lower accuracy for types 2, 3, 5 and 6. The authors concluded that the scale had substantial validity and reliability, but noted that the categories closest to the clinical decision points were the hardest to classify. That is a small sample from one setting, so it supports modest confidence in the numbers rather than a precise measurement.
A later analysis by Vork and colleagues points out that the scale was originally developed as a surrogate marker of whole-gut transit time but is often used as a measure of stool consistency. They highlight the relatively low correlation with more objective measures and the importance of who is doing the rating.
In practice this means a difference of one step between two entries should not be given much weight. A repeated move from type 3–4 to type 6–7 over several days is a clearer observation than one entry that read 4 instead of 5.
Compare bowel entries with meals without assigning cause
Stool form, timing and symptoms can be placed on the same timeline as meals, sleep and stress. When you review them, describe what the record shows:
- Did looser or harder stools occur on several days rather than once?
- Did the same change happen on days without the meal you suspect?
- Were there days when you were ill, travelling, or taking a different medicine?
- Which days have no bowel entry at all?
“Looser stools appeared on four of the seven days, including two days without the meal I suspected” is an observation with an exception. “That meal causes diarrhoea” is a conclusion the diary has not earned. The same cautions apply as in Can You Tell Which Meal Caused Bloating?: timing varies, repeats matter, and other explanations remain possible.
When a diary is not the next step
Do not wait for a perfect record before seeking care. The NHS advises an urgent GP appointment or contacting NHS 111 if you are bleeding from your bottom or have bloody diarrhoea, and for other warning signs including unexplained weight loss and a lump or swelling in the tummy. It also advises seeing a GP if you think you might have IBS and have had symptoms for more than four weeks.
If a doctor or dietitian is going to see your notes, a short summary of how often, what form, and what else was happening is easier to use than a long log. How to Summarise Digestive Symptoms for a GP Appointment shows how to turn entries like these into one page.
GutBloom is designed to let you log a bowel movement with an optional Bristol Stool Scale value beside meals, symptoms and context on one timeline. If that would make this easier to keep up, you can get GutBloom on Google Play.
Sources
- Bladder and Bowel Community — Bristol Stool Chart
- NICE — Irritable bowel syndrome in adults: diagnosis and management (CG61), recommendations
- University Hospitals Dorset — Bowel habit diary (February 2022)
- Blake, Raker and Whelan — Validity and reliability of the Bristol Stool Form Scale in healthy adults and patients with diarrhoea-predominant irritable bowel syndrome (2016)
- Vork and colleagues — Stool consistency: looking beyond the Bristol Stool Form Scale (2019)
- NHS — Symptoms of IBS