Ask most appointment business owners what their diary utilisation rate is and you will get a blank look, a rough guess or a confident answer that turns out to be based on how busy the week felt rather than what the numbers actually show. Diary utilisation is the percentage of available appointment slots that are filled across a given period, and it is one of the most commercially significant metrics in any appointment-led business. It is also the one most consistently ignored. A business that feels busy can still be running at 70% utilisation, which means 30% of its revenue-generating capacity is sitting empty every week. This post covers what your utilisation rate is actually telling you, how to read the gap patterns that reveal where the problem is, and the fixes that fill those gaps without requiring more marketing spend or more staff.