Inventory glossary
What is Lumpy demand?
Lumpy demand is a sales pattern where orders for a product arrive in irregular bursts with long quiet gaps in between, instead of a steady flow of units each week.
For a small Shopify store, lumpy demand makes forecasting harder because average daily sales can be misleading. A SKU that sells 20 units one week and 0 units the next three weeks will look slow on paper, but you still need stock ready for the next burst.
To handle it, look at the pattern over a longer window instead of recent weeks alone, and plan around the size and frequency of bursts rather than a smooth daily rate. Keep a bit of extra buffer stock on lumpy SKUs so a sudden order doesn't push you into a stockout while you wait on a supplier.
Example
A candle store sells a seasonal scent in bursts: 30 units in week 1, 0 in weeks 2 and 3, then 25 units in week 4. Average daily sales over the month works out to about 2 units a day, but that number never actually happens on any single day. Ordering stock based on that flat average would leave the store short right when a burst hits.
Common mistakes
- Using a simple daily or weekly average to set reorder points, which smooths out the bursts and understates peak need.
- Treating a lumpy SKU as dead stock just because it had several quiet weeks in a row.
- Not keeping enough buffer stock to cover a sudden burst while waiting on supplier lead time.
Lumpy demand and SteadyShelf
SteadyShelf's forecasts look at each variant's actual sales pattern over time, so lumpy SKUs get an order-by date and quantity that accounts for burst-and-gap behavior rather than a flat average.
SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.
Related terms
Demand variability · Intermittent demand · Safety stock · Demand forecasting · Buffer stock
FAQ
How is lumpy demand different from seasonal demand?
Seasonal demand follows a predictable calendar pattern, like more sales before holidays. Lumpy demand is irregular and harder to predict, with bursts that don't follow a clear schedule.
Should I stop stocking a product with lumpy demand?
Not necessarily. Check the total units sold over a few months first. If the total is solid, the product is still worth stocking, it just needs a buffer for the gaps between bursts.
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