The vertical range of a single price bar, calculated as Spread = High - Low, and one of the three primary VSA inputs (alongside volume and close position). A wide spread indicates strong activity and willingness to move price; a narrow spread indicates compression and reluctance. VSA classifies the spread relative to the recent average into very narrow (<0.50), narrow (0.50–0.80), average (0.80–1.20), wide (1.20–1.60), and ultra-wide (>1.60). The meaning of any bar emerges only when spread, volume, and close position are read together.