How to calculate schedule adherence
Schedule adherence = scheduled items completed as planned ÷ scheduled items × 100
Decide what "as planned" means and keep it stable: on the planned day or shift, in the planned sequence, and within a tolerance of the planned quantity. A common variant counts an order as adherent only if all three hold.
Why it matters
- The plan is where customer promises, material availability and capacity were reconciled. Every deviation unpicks that reconciliation somewhere else.
- Reshuffling hides problems: a line that hits its volume by running whatever is available, rather than what was scheduled, looks productive while the real constraint goes unaddressed.
- Low adherence creates expediting, extra changeovers, inventory in the wrong products and late deliveries.
Schedule adherence on a tier board
Show adherence per line per shift with the reasons for each missed item: material, equipment, people, quality, planning. The reason mix tells the Tier 2 meeting where to act. Planning problems (an unrealistic schedule) are as common a cause as execution problems.
Improving schedule adherence
- Make the schedule visible at the line, by hour or by shift.
- Record every deviation with a reason at the time.
- Review the reasons daily; solve the recurring ones.
- Feed what the floor learns back to planning: lead times, changeover times and real capacity.
- Reduce changeover time so the schedule can be followed in small batches.
Related measures
On-time-in-full (OTIF) measures delivery to the customer; schedule adherence measures execution of the internal plan. Takt time sets the pace the plan should run to; OEE shows the equipment losses that break the plan.