The load calculation for rough cut capacity planning is a relatively simple infinite scheduling procedure.
For each part supply, from the last day in the lead time to the first day in the lead time of the resource requirements for the part, calculate the load as the supply quantity multiplied by the hours of resource requirement. Since the supply quantity and resource hours has lower, expected and upper values, the load will be calculated for all nine possible combinations of supply quantities and resource hours.
The load is placed on the supply date offset to the day of the resource requirement in relation to the lead time of the part. This load is moved to the next earliest workday with capacity if no capacity exists on initially planned date. If no capacity exists earlier than initially planned, then the load is placed on the date initially calculated. Resource requirements on earlier days in the lead time are adjusted earlier by an amount corresponding to any adjustment made on resource requirements on later days in the lead time.
For example, given part A with a 7 day lead time and resource requirements as follows:
| Lead Time Day | Resource | Lower Hours | Expected Hours | Upper Hours |
| -3 | CNC Lathe | 1 | 2 | 3 |
| -7 | Grinding | 1 | 1 | 2 |
And a supply of:
| Supply Date | 15 April |
| Quantity Lower | 4 |
| Quantity Expected | 6 |
| Quantity Upper | 8 |
With the CNC Lathe Resource having capacity of:
| Date | 1 April | 8 April | 15 April |
| Hours | 40 | 40 | 40 |
And the Grinding Resource having capacity of:
| Date | 4 April | 8 April | 15 April |
| Hours | 40 | 40 | 40 |
The load would be as follows:
| Date | Resource | Lower Hours / Lower Supply |
Expected Hours / Expected Supply |
Upper Hours / Upper Supply |
| 4 April | Grinding | 1 * 4 = 4 | 1 * 6 = 6 | 2 * 8 = 16 |
| 8 April | CNC Lathe | 1 * 4 = 4 | 2 * 6 = 12 | 3 * 8 = 24 |
The load for CNC Lathe is initially placed on 12 April, but there is no capacity on this date. So, the next previous date of available capacity on 8 April is used.
This pushes the load on the preceding resource requirement for Grinding to 4 April.