Disclosure: Get Regular publishes this guide and makes a gut-health tracking app. Product descriptions are attributed to public sources; this article is not an independent hands-on test or clinical validation.
Quick answer: Yes, some apps can suggest a Bristol stool type from a photo. In one peer-reviewed study, a smartphone AI agreed well with two gastroenterologists on stool type in 14 people with IBS-D, and beat patients' own ratings [1]. But the study was small, covered one app and one condition, and says nothing about other apps. A photo can't diagnose anything, find hidden blood or explain cause. Treat an AI read as a suggestion to check, not a result.
The word "analyzer" does a lot of work in this category. It can mean a trained image model that grades stool form, a diary with a photo attachment, or a joke app. This guide separates them, walks through the best published evidence (and what it can't tell you), and gives you a way to use an AI stool read without over-trusting it.
Key takeaways
- The best-known evidence is a 2022 study of one smartphone AI in adults with IBS-D: good agreement with two expert gastroenterologists (14 people), and only moderate agreement with the patients' own ratings (25 people) [1].
- That result doesn't transfer automatically to other apps, other conditions, children or other lighting and cameras.
- A photo can suggest stool form. It can't rule out bleeding, infection or disease; black, tar-like or red stool needs a doctor, not an app [4][5].
- Manual Bristol entry is a legitimate alternative if you'd rather not upload a photo.
What is a poop analyzer app?
A poop analyzer app is an app that tries to describe your stool, usually its Bristol type, from a photo or from what you enter. Three different things share the name.
For ongoing records, explore the Get Regular food and symptom tracker. Check the current workflow, privacy information and access before entering sensitive information. A recorded association is a question to investigate, not a confirmed trigger.
The Bristol Stool Form Scale is a seven-type chart of stool form; its original paper presents it as a useful guide to intestinal transit time [2]. It's what almost every photo classifier outputs. See the Bristol stool chart for the types.
What does the research say about AI stool photo accuracy?
The best published evidence is a 2022 study in the American Journal of Gastroenterology by Pimentel and colleagues, which tested one smartphone app's AI on people with diarrhea-predominant IBS. It found good agreement with expert gastroenterologists, but it was small [1].
The study at a glance
| Question | Can a trained AI in a smartphone app assess stool characteristics accurately? |
| Who | Adults with diarrhea-predominant irritable bowel syndrome (IBS-D) |
| Method | Participants photographed every stool for 2 weeks. The AI rated five visual traits: Bristol type, consistency, fragmentation, edge fuzziness and volume |
| Validation phase (14 people) | Two expert gastroenterologists served as the gold standard. Agreement between the experts and the AI: Bristol type, intraclass correlation (ICC) 0.782 to 0.852; consistency 0.873 to 0.890; edge fuzziness 0.836 to 0.839; fragmentation 0.837 to 0.863; volume 0.725 to 0.851. The AI also did better than participants' self-reports at sorting daily average Bristol scores into constipation, normal or diarrhea |
| Implementation phase (25 people) | Agreement between AI-graded and self-reported daily average Bristol scores was moderate (ICC 0.61). The AI's stool characterisation correlated better with diarrhea severity scores than the participants' own reports did |
| Authors' conclusion | The app can assess stool type and other visual traits with high accuracy against two gastroenterologists, and the AI was superior to self-reporting; AI assessments could give more objective outcome measures for stool in gastroenterology |
An intraclass correlation coefficient (ICC) is a measure of agreement between raters where 1.0 would be perfect; the authors describe the 0.78 to 0.85 range for Bristol type as good agreement [1].
What can a stool photo show, and what can't it?
A photo can show stool form and, roughly, volume and consistency. It can't reliably show cause, hidden blood, infection or disease, and its read of color depends on context.
| Trait | A photo can help with | Limits |
|---|---|---|
| Form (Bristol type) | Yes: the best-supported use [1] | Lighting, angle, toilet water and photo quality all change what the model sees |
| Consistency, fragmentation, volume | The study's AI rated these against experts in IBS-D [1] | Not shown for other conditions or other apps |
| Color | A rough impression | Medicines and foods change color: the NHS says darker stool is common with iron tablets and usually nothing to worry about, yet black, tar-like or red stool needs urgent medical advice [5]. An app can't tell which applies |
| Blood | Visible red or black only | Blood in poo "may look red or black" and is a symptom to get checked by a doctor [4]; microscopic blood isn't visible at all |
| Frequency and timing | No | Needs a log |
| Cause | No | A photo can't tell you what you ate, what you're intolerant to, or whether you have a condition |
For color questions, see the poop color chart, and for symptoms that need a clinician, when to see a doctor about bowel changes.
How do apps describe their stool AI?
Listings use confident language, and few link to accuracy data. Here's what several US listings say, checked 19 Oct 2026, and what to ask about each. We haven't tested these apps, and a bold listing isn't proof an app is inaccurate; it's just a claim to check.
Two points on regulation. First, the FDA's general wellness policy says software intended "for maintaining or encouraging a healthy lifestyle and is unrelated to the diagnosis, cure, mitigation, prevention, or treatment of a disease or condition" is not a device [3]. Apps that stay in that lane generally don't go through FDA review, so the absence of a regulator's name isn't a sign of review either way. Second, any app that implies a photo reveals inflammation, infection or a condition is moving toward medical claims that need much stronger evidence than a Bristol-type study.
What happens to your stool photo?
Where the photo goes matters as much as what the AI says. Ask whether the photo is uploaded, kept, shared with an AI provider or saved to your camera roll.
How should you use an AI stool read?
Use an AI stool read as a second opinion on stool form, not as a verdict on your health. Four habits make it much more useful.
- Check it. If the suggested type doesn't match what you saw, correct it where the app allows, or use manual entry for that log. Garbage in, garbage out applies to your own log too.
- Photograph consistently. Same lighting, same angle, no flash glare. Inconsistent photos create fake "changes".
- Log context beside it. Foods, medicines (iron, bismuth, charcoal), supplements and symptoms explain more than the photo does.
- Look at the trend, not the single read. Review a description in context, without waiting for a fixed period if you have symptoms that concern you.
the AI-read sanity check.
If the AI says... Ask yourself Then A Bristol type that matches what you saw Does it match for a week? Keep it; a steady log is the point A type that doesn't match Was the photo clear? Correct it if the app lets you, or use manual entry for that entry A color or "insight" about health Did you take iron, bismuth, charcoal, or eat dark or brightly colored food? Add it to the log; treat the insight as unverified Anything about blood, black or tar-like stool Is it black, tar-like or red? Don't wait for the app: get medical advice [4][5] A "gut score" or "health" claim What's it built from? See how gut health scores are built
Should you use photos or manual entry?
Choose photos if you struggle to pick a Bristol type and are comfortable with the privacy trade-off; choose manual entry if you know the types or don't want an image leaving your phone.
| Photo + AI | Manual Bristol entry | |
|---|---|---|
| Speed | Fast once you're used to it | Fast if you know the chart |
| Consistency | AI applies the same rules each time (within photo quality) | Depends on you |
| Privacy | Image is processed, possibly off-device | Nothing leaves your phone unless the app syncs entries |
| Best for | People unsure of the types; people who dislike typing | People who know the chart; privacy-first users |
How to track stool with or without AI
Whatever you use, log each movement with a Bristol type and a time, log the days you don't go, and add symptoms separately. For the full method, see best poop tracker apps.
- Log each bowel movement soon after it happens, with a Bristol type.
- Log "no bowel movement" days too.
- Add blood, mucus, urgency or pain if the app has fields for them.
- Note medicines and supplements that change stool color.
- Review weekly for trends, and bring the log to your clinician.
When to see a doctor
Don't wait for an app to tell you whether something is wrong. The NHS lists blood in your poo (which may look red or black), changes in bowel habit that aren't usual for you and losing weight without trying as symptoms to get checked by a GP [4]. NIDDK lists rectal bleeding, bloody or black, tarry stools, weight loss and anemia as symptoms that may suggest a problem other than IBS [6]. See a doctor promptly if you have:
- Blood in your stool, or black, tar-like or red stool
- Unintended weight loss, or anemia
- Severe or worsening abdominal pain, fever, or symptoms that wake you at night
- A change in bowel habits that lasts, especially after age 50 or with a family history of colorectal cancer, inflammatory bowel disease or celiac disease
FAQ
Can an app analyze a photo of my poop? Yes, in the sense that some apps use AI to suggest a Bristol stool type from a photo. One peer-reviewed study found one app's AI agreed well with two gastroenterologists in 14 people with IBS-D [1]. It's a suggestion about stool form, not a medical analysis.
How accurate is AI stool analysis? It depends on the app, and published evidence is thin. The best-known study found good agreement with experts for Bristol type (ICC 0.782 to 0.852) in 14 people with IBS-D, and moderate agreement with participants' own ratings (ICC 0.61) in 25 people [1]. It didn't test other apps, other conditions or disease detection.
Can a poop photo diagnose a condition? No. A photo can show form and rough color; it can't establish cause or rule out disease. A diagnosis comes from a clinician who reviews your symptoms and history and may order tests [6].
Is it safe to upload stool photos to an app? It depends on the app's data handling. Check whether the photo is uploaded, retained, sent to a third-party AI provider or saved to your camera roll, and use manual entry if you'd rather avoid uploads (checklist).
Sources
- Pimentel M, Mathur R, Wang J, et al. A Smartphone Application Using Artificial Intelligence Is Superior To Subject Self-Reporting When Assessing Stool Form. Am J Gastroenterol 2022;117(7):1118-1124. https://pubmed.ncbi.nlm.nih.gov/35288511/ (DOI 10.14309/ajg.0000000000001723)
- Lewis SJ, Heaton KW. Stool form scale as a useful guide to intestinal transit time. Scand J Gastroenterol 1997. https://pubmed.ncbi.nlm.nih.gov/9299672/
- US FDA. General Wellness: Policy for Low Risk Devices (January 2026). https://www.fda.gov/regulatory-information/search-fda-guidance-documents/general-wellness-policy-low-risk-devices
- NHS. Symptoms of bowel cancer. https://www.nhs.uk/conditions/bowel-cancer/symptoms/
- NHS. Side effects of ferrous sulfate. https://www.nhs.uk/medicines/ferrous-sulfate/side-effects-of-ferrous-sulfate/
- NIDDK. Diagnosis of Irritable Bowel Syndrome. https://www.niddk.nih.gov/health-information/digestive-diseases/irritable-bowel-syndrome/diagnosis
- App Store (US). Get Regular: AI Gut Health. https://apps.apple.com/us/app/id6749188690 (checked 19 Oct 2026)
- Get Regular. Privacy Policy (last updated 8 June 2026). https://www.getregular.com/legal/privacy-policy
- App Store (US). Flush: Poop & Gut Health Scan. https://apps.apple.com/us/app/id6748068252 (checked 19 Oct 2026)
- App Store (US). PoopCheck: AI Poop Tracker. https://apps.apple.com/us/app/id6737857695 (checked 19 Oct 2026)
- App Store (US). KB Poop Tracker: AI Stool Scan. https://apps.apple.com/us/app/id6784489026 (checked 19 Oct 2026)
- App Store (US). plop - poop tracker & analyzer. https://apps.apple.com/us/app/id1505427265 (checked 19 Oct 2026)
- App Store (US). Poop Analyzer. https://apps.apple.com/us/app/id455210043 (checked 19 Oct 2026)
This article is for general education and isn't medical advice. Get Regular is a tracking app — it doesn't diagnose or treat any condition. If you have red-flag symptoms or ongoing changes in your digestion, talk to a doctor.