Calculator Inputs
Use the fields below to estimate load, effective capacity, shortages, and the most likely production bottleneck.
Example Data Table
This sample shows how a typical monthly capacity plan translates demand into machine and labor requirements.
| Item | Sample Value | Explanation |
|---|---|---|
| Forecast Units | 1,200 | Planned market demand for the period. |
| Customer Orders Units | 1,100 | Confirmed demand already booked. |
| Net Production Units | 1,070 | Demand after inventory, receipts, and safety stock adjustments. |
| Adjusted Units for Scrap | 1,114.58 | Higher production quantity to cover expected losses. |
| Required Machine Hours | 519.56 | Run hours plus setup time. |
| Required Labor Hours | 352.37 | Labor content including setup time. |
| Effective Machine Capacity | 979.20 | Rated hours after efficiency and utilization factors. |
| Load Ratio | 0.53 | Required hours divided by effective hours. |
Formula Used
Gross Requirement = max(Forecast Units, Customer Orders Units)
Net Production = max(0, Gross Requirement + Safety Stock - Beginning Inventory - Scheduled Receipts)
Adjusted Units = Net Production / (1 - Scrap Rate)
Machine Run Hours = Adjusted Units × Machine Hours per Unit
Labor Run Hours = Adjusted Units × Labor Hours per Unit
Total Setup Hours = Setup Hours per Run × Planned Runs
Required Machine Hours = Machine Run Hours + Total Setup Hours
Required Labor Hours = Labor Run Hours + Total Setup Hours
Rated Capacity = Resources Available × Shifts per Day × Hours per Shift × Working Days
Effective Capacity = Rated Capacity × Efficiency × Utilization
Load Ratio = Required Hours / Effective Capacity
How to Use This Calculator
- Enter forecast demand and confirmed orders for the planning period.
- Add safety stock, beginning inventory, and scheduled receipts.
- Enter scrap percentage to account for expected production loss.
- Provide standard machine hours and labor hours per unit.
- Enter setup hours and expected number of production runs.
- Specify available machines, operators, shifts, shift length, and working days.
- Set efficiency and utilization percentages to reflect realistic capacity.
- Submit the form to review shortages, slack, load ratios, and the bottleneck area.
Frequently Asked Questions
1. What does capacity requirement planning measure?
It estimates how many machine and labor hours are needed to meet planned production. It then compares that demand with effective available capacity.
2. Why does the calculator use the higher of forecast and orders?
Using the higher value helps protect planning against underestimating demand. Many planners use this as a practical rule when balancing forecast signals and booked orders.
3. Why is scrap included in the plan?
Scrap increases the number of units you must start to deliver the required good output. Ignoring scrap can make capacity plans look easier than they are.
4. What is the difference between rated and effective capacity?
Rated capacity is the theoretical available time. Effective capacity reduces that total by efficiency and utilization, giving a more realistic planning figure.
5. What does a load ratio above 1 mean?
A load ratio above 1 means required hours exceed effective capacity. This usually signals overtime, extra shifts, subcontracting, or schedule changes may be needed.
6. Why are setup hours added separately?
Setup time does not scale directly with units. It depends on how many runs or changeovers are planned, so it should be tracked separately.
7. How can I reduce overload in the results?
You can reduce demand, improve efficiency, increase utilization, add shifts, extend hours, add resources, or reduce the number of setups through larger batch sizes.
8. Is this calculator useful for rough-cut planning?
Yes. It works well for quick feasibility checks, monthly reviews, and work center planning. Detailed finite scheduling may still need more granular routing data.