Demand forecasting
Demand Planning
By the Supply Chain Manager team · Updated October 16, 2026
Demand planning is the process of forecasting future demand and refining it with market knowledge so purchasing and inventory decisions rest on one view.
A statistical forecast is the starting point. Demand planning adds what the history cannot know: a lost customer, a new contract, a price change, a product being replaced. The output is the demand plan that drives replenishment.
The most useful habit is to record every manual override and check later whether it improved the forecast. Over time, that shows which kinds of human input add value, such as known contract wins, and which do not, such as general optimism. Keeping overrides that work and dropping the rest makes the plan better each cycle.
Demand planning example
Illustrative: the statistical forecast for a cable range shows steady demand, but sales knows a large customer is switching to a competitor next month. The demand planner cuts that customer's share from the forecast before the next purchase orders go out.
Why demand planning matters for distributors
Good demand planning lets purchasing act early. It is the difference between buying for the market you will have and buying for the one you had.
Common demand planning mistakes
- Overriding the statistical forecast with opinions that are never checked afterwards.
- Planning only in revenue, without translating to units by SKU and warehouse.
Examples on this page use made-up round numbers to show the calculation. They are not benchmarks or results from real businesses.