ERP & MRP Planning worked example

Work Order Aging with total open work-order age of 630 order-days: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop total open work-order age to 630 order-days, then walk the calculation through step by step. Estimate average open work-order age from total aged order-days and open work-order count.

The inputs for this scenario

  • Total open work-order age: 630 order-days (the input this scenario stresses; the baseline uses 1,260)
  • Open work-order count: 84 orders (held at the documented default)
  • Calendar adjustment factor: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Average work-order age = total open work-order age ÷ open work-order count × calendar adjustment factor.
  • Average work-order age works out to 7.5 days at these inputs, and this is the headline figure for the scenario.
  • Average age before calendar adjustment works out to 7.5 days at these inputs.
  • Calendar adjustment factor works out to 1 x at these inputs.
  • Open work-order count works out to 84 orders at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where total open work-order age sits at 1,260 order-days and the headline result is 15 days, this scenario comes in 50% below the baseline at 7.5 days.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to total open work-order age, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. An average hides outliers — a few very old orders can be masked by many fresh ones, so pair it with an aging distribution.

Results at a glance

  • Average work-order age: 7.5 days (headline result)
  • Average age before calendar adjustment: 7.5 days
  • Calendar adjustment factor: 1 x
  • Open work-order count: 84 orders

Run it with your numbers

  • To rerun this with your own numbers, open the live Work Order Aging calculator, set total open work-order age to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.