Demand Planning — Why Splitting Monthly Forecasts Evenly Across Weeks Hurts Your Supply Plan

Worst Practices Supply Chain Planning: Equal-Split Weekly Disaggregation That Erases Real Demand Patterns

📉 Equal-split forecasts in SAP IBP: convenient, but is it costing you? 🤔

A pattern I see often in IBP implementations: the monthly forecast gets disaggregated to weeks using an equal split.

400 units in the month?

That becomes 100 / 100 / 100 / 100 across the four weeks. Clean. Simple. ✨

And in the example below, it lets the open forecast key figure calculate neatly against actual sales orders. However weekly demand rarely has a uniform pattern — if it does then you are lucky. It has a pattern of its own.

If you did not design your SAP IBP the right away, then you have to use complex consumption rules to take care of actual weekly demand patterns (and of course fret over in the S&OE meetings).

✅ Why teams default to equal split:

⚡ Fast to configure, easy to explain to the business 🧮 Keeps monthly totals intact, so S&OP numbers reconcile cleanly 📈 Works reasonably well for products with stable, non-seasonal weekly demand 🔄 Simplifies forecast consumption logic when sales orders arrive lumpy

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