The Bristol Stool Scale (BSS), also known as the Bristol Stool Form Scale (BSFS) or Bristol Stool Chart, is a diagnostic medical tool designed to classify human feces into seven distinct categories based on their form and consistency.
Developed in 1997 at the Bristol Royal Infirmary, it has become widely used in both clinical and research settings.

The scale is used for many reasons:

• Helps find out diagnostics:  It helps healthcare professionals assess various digestive issues and bowel function
• Communication tool: It provides a standardized way for patients to describe their stool to doctors without bringing samples
• Research instrument: The scale is used to evaluate the effectiveness of treatments for various bowel diseases1.
• Clinical assessment: It's part of the diagnostic triad for irritable bowel syndrome (IBS)
• Estimating transit time: The shape and form of stool can indicate how long food has taken to pass through the digestive system