Roofing, Siding & Exterior Building Products worked example

Regional Demand Forecast at 65% in-stock service level: a worked example

This worked example runs the regional demand forecast numbers for a tougher week than the baseline: 65% in-stock service level instead of the typical 90%. Estimate regional demand forecast for roofing, siding and exterior building products using production-ready inputs so teams can confirm whether capacity can cover demand before committing the schedule.

The inputs for this scenario

  • Panels demanded per selling cycle: 4 units / cycle (held at the documented default)
  • Selling cycles in the forecast horizon: 480 cycles (held at the documented default)
  • In-stock service level: 65 % (the input this scenario stresses; the baseline uses 90)
  • Order fill (non-return) rate: 97 % (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Gross regional demand forecast capacity = regional demand forecast output per cycle × available regional demand forecast cycles.
  • Good regional demand forecast capacity works out to 1,211 units at these inputs, and this is the headline figure for the scenario.
  • Gross regional demand forecast capacity works out to 1,920 units at these inputs.
  • Regional demand forecast downtime loss works out to 672 units at these inputs.
  • Regional demand forecast yield loss works out to 37.44 units at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where in-stock service level sits at 90% and the headline result is 1,676 units, this scenario comes in 27.78% below the baseline at 1,211 units.
  • Use it when allocating production to regions, sizing regional inventory, or setting a realistic sales forecast that reflects service and returns. A result at this level usually justifies acting on the stressed input before touching anything else, because every other figure in the table is downstream of it.

Results at a glance

  • Good regional demand forecast capacity: 1,211 units (headline result)
  • Gross regional demand forecast capacity: 1,920 units
  • Regional demand forecast downtime loss: 672 units
  • Regional demand forecast yield loss: 37.44 units

Run it with your numbers

  • To rerun this with your own numbers, open the live Regional Demand Forecast calculator, set in-stock service level to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.