Capacity planning asks whether a plan is actually executable. MRP works out material shortages but says nothing about whether the equipment or people exist to do the work.
The limitation in MRP
MRP assumes infinite capacity โ that whatever is needed can be made on the day it is needed. The result can be a plan that puts three days of work into one day. Material is available; the line is not.
Calculating capacity requirements
Order: 200 units of product X
Routing: setup 1.0 h (fixed)
machine 0.05 h per unit
Capacity requirement = 1.0 + (0.05 x 200) = 11.0 hoursAvailable capacity
| Element | Content | Example |
|---|---|---|
| Start and finish times | The operating window | 08:00โ17:00 |
| Breaks | Deducted from the window | 1 hour |
| Utilisation rate | The proportion genuinely usable | 85% |
| Number of capacities | How many identical units exist | 3 machines |
| Factory calendar | Which days are worked | Excluding weekends and holidays |
9 hours - 1 hour break = 8 hours
8 hours x 85% utilisation = 6.8 hours
6.8 hours x 3 machines = 20.4 hours per dayEvaluation and levelling
| Code | Content |
|---|---|
| CM01 | Load by work centre, standard view |
| CM02 | Load by order |
| CM05 | Overloaded work centres only |
| CM21 | Levelling via the planning table |
| CM25 | Graphical levelling |
Where overload appears, levelling adjusts it: move orders earlier or later, move them to another work centre, add capacity through overtime, or subcontract.
Scheduling
| Method | Anchor | Behaviour |
|---|---|---|
| Backward | Due date | Work back to a start date; the usual method |
| Forward | Start date | Work forward to a finish date |
| Current date | Today | Used when backward scheduling produces a start date in the past |
| Only capacity requirements | โ | Calculate load without setting dates |
Backward is the default. Where it produces a start date already passed, SAP switches to current-date scheduling and warns โ which means the due date cannot be met.
Focus on the bottleneck
Not every work centre needs planning in detail: throughput is set by the most constrained operation. The work centre master controls whether capacity requirements are generated at all, so planning only bottlenecks is a realistic approach. Planning everything inflates data volume and effort until the plan stops being maintained.