Sales Velocity
Also known as: Velocity
Units sold per unit of time — usually days or weeks. The single most important demand signal for restock planning.
Sales Velocity is units sold per unit of time, typically expressed as units per day or units per week. It's the foundational input for every inventory decision: forecasting, reorder points, safety stock, days of cover, and storage cost projections all start with velocity.
The trap with velocity: which window do you measure? 30-day average smooths out short-term noise but lags trend changes. 7-day average tracks recent shifts but is volatile. The right approach is to track multiple windows side by side and pay attention to the direction of change. A SKU with 30-day velocity of 8/day and 7-day velocity of 14/day is accelerating — your reorder point assumptions from a week ago are already wrong.
Seasonality compounds the problem. Q4 velocity for a Christmas item is 10x its baseline, but the average across the year hides that. Good inventory tools weight velocity by recency AND adjust for seasonality. SellerVault's Monte Carlo forecasting produces a probabilistic velocity range that flexes with both recent trend and historical seasonality.