Bristol Stool Scale Calculator

The Bristol Stool Scale is a validated 7-type visual classification of stool form, widely used in both clinical practice and research because it is a reasonably reliable proxy for colonic transit time -- how long stool spends moving through the colon -- without requiring a formal transit study. Types 1 and 2 (hard, separate lumps or a lumpy sausage shape) reflect slow transit and are associated with constipation; types 3 and 4 (a cracked or smooth sausage shape) are considered normal, with type 4 often cited as the "ideal" form; and types 5 through 7 (soft blobs through entirely liquid) reflect progressively faster transit and are associated with diarrhea. This calculator pairs the stool type with additional symptom questions (urgency, straining, and a sense of incomplete evacuation) and a simplified screen against the Rome IV functional constipation and diarrhea-predominant IBS criteria -- simplified because it checks the general shape of those criteria (frequency, stool form, straining, and incompleteness) rather than the complete, clinician-administered Rome IV interview, and does not account for alarm features or duration requirements the full criteria specify. Estimated colonic transit time, fiber recommendations, and hydration targets are all approximate, general guidance tied to the broad constipation/normal/diarrhea classification rather than individually validated numbers, and are explicitly labeled as such in the underlying model.

Bristol type and bowel habit tracked over multiple days is far more informative than any single reading -- but within this calculator, Days Tracked itself is used only to compute Total BMs in Period (frequency per day multiplied across the tracked days); it does not otherwise change the classification, transit-time estimate, or Rome IV screens, which are all based on the single stool-type and symptom-severity selections entered. In real clinical use, the value of multi-day tracking comes from repeating this assessment across several days and looking at the pattern across those results, not from any calculation this tool performs internally on the days-tracked number. Persistent abnormal patterns -- especially with alarm features like bleeding, weight loss, or nighttime symptoms -- warrant clinical evaluation rather than reliance on a self-screening tool like this one.