Inventory glossary
What is Product velocity?
Product velocity is the speed at which a specific product or variant sells over a given period, usually measured in units sold per day, week or month.
Velocity tells you which products deserve shelf space and reorder attention, and which ones are quietly stalling. A candle that sells 20 units a week needs a very different reorder plan than one that sells 2 units a week, even if both show the same total stock on hand.
Use velocity to set reorder timing and order quantities, and to spot products speeding up or slowing down before you get stuck with too much or too little stock. Rising velocity signals you should order sooner or in bigger batches. Falling velocity is a warning to cut the next order size or stop reordering altogether.
Formula
Example
A candle shop sells 84 units of its lavender candle over 28 days. Velocity is 84 / 28 = 3 units per day. If the same candle sells only 28 units over the next 28 days, velocity drops to 1 unit per day, signalling slower demand.
Common mistakes
- Measuring velocity over too short a period, so one busy or slow day skews the number.
- Ignoring stockouts, which make a product look slower than real demand because it wasn't available to sell.
- Treating all variants of a product as one line instead of tracking velocity per SKU.
Product velocity and SteadyShelf
SteadyShelf tracks sales velocity per variant to forecast demand and suggest when and how much to reorder of each SKU.
SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.
Related terms
Average daily sales · Demand forecasting · Sell-through rate · Days of supply · Reorder point
FAQ
What counts as good product velocity?
There is no universal good number. It depends on your store's size, category and stock levels. What matters is comparing a product's velocity to its own history and to similar products, so you can spot items speeding up or slowing down.
How is product velocity different from inventory turnover?
Velocity measures units sold per time period for one product, while inventory turnover measures how many times total stock is sold and replaced over a period, usually across the whole store or category.
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