Capacity that is 100% booked is already fragile.
A shop needs room for rework, rush orders, maintenance, approvals and jobs that take longer than the average. This planner treats your reserve as unavailable capacity and asks when normal or peak demand consumes the rest.
Forecast three versions of demand
Run a base case, a slower-growth case and a peak case rather than treating one growth percentage as truth. The planner is not a sales forecast; it is a sensitivity test. Its value is showing how soon the purchase decision changes when your assumptions move.
| Run | What to change | Question answered |
|---|---|---|
| Base | Your best current growth estimate | When does normal capacity become uncomfortable? |
| Slow | Lower growth or flatter demand | How much runway exists if sales cool? |
| Peak | Higher seasonal multiplier | Can the current shop survive the busiest realistic week? |
Use measured good capacity
Do not enter heads × rated SPM. Use good pieces completed under a representative workload after normal handling and rework. If you need a better input, calibrate a real run and use the Shop Calibration Calculator.
Measured capacity should represent a sustainable week, not a heroic record shift. If the input already assumes overtime or unusually easy work, the runway will look longer than the shop can reliably deliver.
What to do with the crossing month
The crossing month is a research trigger, not an automatic buy signal. Validate whether the constraint is machine time, operator time, batch fragmentation, floor space or a short seasonal spike. A staffing or scheduling change can be cheaper than equipment when the bottleneck is not the machine.
If a backlog is already visible, switch from forecasting to flow control. The Backlog Clearance Planner tells you whether current daily capacity is actually draining the ready queue.
Worked example
Suppose measured capacity is 420 good pieces per week and you reserve 15%, leaving 357 pieces as usable planning capacity. Current demand is 250. At 3% monthly growth, the normal-demand crossing may still be many months away, while a 1.35 peak multiplier can create a much earlier pressure point. That gap is exactly why normal and peak runway should be tracked separately.
Turn the chart into an action calendar
Work backward from the earliest uncomfortable scenario. Leave time for quote collection, sample runs, financing, delivery, electrical or floor changes, training and a ramp period. A machine that arrives after peak pressure begins does not solve the planning problem that triggered the purchase.
Also write down the condition that would cancel the purchase: slower demand, a new operator, process improvement or a product-mix shift. A good capacity plan includes reasons not to spend.