Inventory glossary

What is Demand spike?

A demand spike is a sudden, sharp increase in sales for a product over a short period, well above its normal baseline demand.

Demand spikes matter because they can empty your shelves fast and leave you out of stock while a supplier reorder is still weeks away. For a small Shopify store, one viral post or a surprise feature can turn a slow SKU into your top seller for a few days, and if you were not holding buffer stock you miss those sales.

To use this, watch for spikes early by checking daily sales against your normal average, not just weekly totals. When you spot one, decide quickly whether it is a one-off or the start of a new trend, because that changes whether you place a small top-up order or a much larger one.

Example

A candle store usually sells 10 units a day of its lavender candle. After a blog mentions it, the store sells 90 units in one day. That single day is a demand spike, ten times the normal baseline, and it would wipe out 9 days of typical stock in 24 hours.

Common mistakes

  • Treating a demand spike as the new normal and overordering for months ahead.
  • Ignoring a spike as a fluke and understocking when it repeats the next week.
  • Not separating the spike day from normal days when recalculating average daily sales.

Demand spike and SteadyShelf

SteadyShelf flags sudden jumps in daily sales against a SKU's forecast so you can decide whether to place an early reorder before you run out.

SteadyShelf is launching on the Shopify App Store. Join early access to get the install link first.

Related terms

Average daily sales · Demand variability · Baseline demand · Promotional lift · Lumpy demand

Full inventory glossary

FAQ

Is a demand spike the same as seasonality?

No. Seasonality is a predictable, repeating pattern, like more coffee sales in winter. A demand spike is sudden and often unpredictable, like a one-day surge from social media.

Should I always reorder immediately after a demand spike?

Not always. Check if sales stay high for a few more days before placing a large order, since a single spike day can be a one-off that does not repeat.

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