CRP (Capacity Requirements Planning) is detailed capacity planning. While MRP calculates which materials are needed in what quantity and when, CRP answers the next question: do the available capacities – machines, lines, personnel – actually cover the planned production orders within the required timeframe?
Without CRP, MRP produces formally correct order proposals that the plant can never execute on capacity.
In classic MRP II, CRP sits between material planning and detailed scheduling. S&OP sets volume at product family level. MPS defines the master production schedule. RCCP runs a rough capacity check on bottleneck resources. MRP generates concrete production orders. CRP checks whether those orders are actually feasible at workstation and machine level.
The difference between RCCP and CRP is aggregation level: RCCP is the rough check at high level, CRP is the detailed check per workstation and period.
CRP works with three data views. Production orders from MRP with quantities, dates and routings. Standard times per operation – setup times, run times, overlaps. Available capacities per workstation, shift and period accounting for planned downtime.
The logic is straightforward: capacity requirement per operation equals standard time multiplied by quantity. Summed across all orders per workstation and period, the result is demand versus available capacity. Below one hundred percent means underload, above one hundred percent means overload requiring action.
Classic CRP typically works with infinite capacity: it makes bottlenecks transparent while detailed scheduling resolves conflicts through rescheduling, splitting or shift adjustments.
CRP does not fail because of mathematics – it fails because of master data. Standard times estimated once and never validated against actual data. Capacities planned at theoretical one hundred percent availability without accounting for failures and changeover losses. Overly granular models that nobody maintains. And missing feedback from the shopfloor.
Feeding real OEE values, actual cycle times and measured setup times from the MES into planning parameters produces a CRP that is used rather than ignored. ERP and APS calculate the capacity requirements, the MES supplies the actual data for realistic parameters. Without this feedback loop, CRP remains a theoretical model.
What is the difference between CRP and RCCP? RCCP is the rough capacity check on bottleneck resources and product family basis, typically in a weekly to monthly horizon. CRP is the detailed check at workstation and machine level based on concrete production orders. Both complement each other – RCCP shows whether the program is broadly feasible, CRP shows exactly where overload occurs.
Is CRP worthwhile without a full MRP II system? Yes – even a simplified capacity model at bottleneck level provides more planning reliability than pure experience-based estimation. Effort should match the complexity of the operation: rather than modeling every resource, start with the three to five real bottlenecks.
Does CRP replace detailed scheduling? No. CRP identifies where capacity problems arise but does not resolve them automatically. Detailed scheduling – APS or production control – prioritizes, sequences and smooths orders accounting for concrete constraints such as changeover matrices, campaigns and sequence optimization.