Blog · Forecast and pipeline · Manufacturing
Convert a supplied demand plan into production requirements after inventory and scheduled supply. Use Excel formulas to reconcile finished units, check capacity and expose timing constraints.
Production planning forecasting turns a supplied demand plan into the finished units the factory needs to make, then tests the required work against available capacity. Deduct usable inventory and scheduled supply, include the approved closing-stock target, and keep the timing of every input visible. The result is a requirement to review before approving a production schedule.
The manufacturing demand forecasting guide owns the customer-demand question: what customers need and how the forecast compares with their requirements. Here that forecast is an input. Production planning and forecasting connect when the operations team translates the supplied demand into output it can actually deliver.
Do not substitute shipments for demand just because they are easier to export. The Census Bureau's manufacturing definitions distinguish shipments, new orders and unfilled orders. A constrained factory can ship less while customer requirements remain outstanding.
Choose one demand basis, such as units required for delivery during November 2026. Specify whether confirmed orders are already included in that forecast. Adding them again would count the same demand twice. Preserve the demand snapshot, inventory snapshot and production-plan version so the review can be rebuilt later.
An illustrative US pump and valve manufacturer needs four inputs for each product at one site:
Record the approver and basis of the stock target.
Use the same unit for every quantity on a product row. Exclude held inventory and distinguish a purchase receipt from an internally scheduled completion. If work in process becomes a scheduled completion here, do not also count it as finished opening inventory.
Place the following table in a worksheet, with headers in row 1 and columns A through G. Scheduled supply represents previously committed completions, separate from the new output requirement.
| Product | November demand | Usable opening | Scheduled supply | Target closing | New output required | Projected closing |
|---|---|---|---|---|---|---|
| Pump | 500 | 120 | 40 | 100 | 440 | 100 |
| Valve | 300 | 60 | 20 | 40 | 260 | 40 |
| Total units | 800 | 180 | 60 | 140 | 700 | 140 |
The governing relationship is:
New output required = MAX(demand + target closing − usable opening − scheduled supply, 0).
Enter these formulas in F2 and G2 and fill down:
=MAX(B2+E2-C2-D2,0)
=C2+D2+F2-B2
Microsoft's MAX documentation explains that MAX returns the largest argument. The zero floor keeps excess stock from becoming negative production. Covirage is not affiliated with Microsoft.
Pump output is 500 + 100 − 120 − 40 = 440 units. Valve output is 300 + 40 − 60 − 20 = 260 units. The new production requirement is 700 units, rather than the 800 units in the demand plan. Inventory and existing supply cover the difference after retaining closing stock.
If stock already exceeds demand plus the target, projected closing will remain above target. Keep that surplus visible. The formula cannot sell excess inventory or reverse an existing production commitment.
Each product must reconcile independently:
Opening inventory + scheduled supply + new production = demand + projected closing inventory.
Pump balances at 120 + 40 + 440 = 500 + 100 = 600 units. Valve balances at 60 + 20 + 260 = 300 + 40 = 340 units. At the combined level, 180 + 60 + 700 = 800 + 140 = 940 units.
In H2, enter and fill down:
=C2+D2+F2-B2-G2
Every result must be zero. Independently reconcile the opening inventory and scheduled supply to their source reports; an identity can balance even when an input is wrong. Keep revisions separate from the approved plan, as explained in budget vs forecast.
Suppose all new output passes through one constrained work center. Its net available time for this additional production is 400 hours, after previously scheduled supply and other commitments have been reserved. The processing standards below include the approved time allowances for this simplified comparison.
| Product | New output required | Hours per unit | Required hours |
|---|---|---|---|
| Pump | 440 | 0.50 | 220 |
| Valve | 260 | 0.75 | 195 |
| Total | 700 | 415 |
On a separate Capacity sheet, put these columns in A through D. Calculate D2 with =B2*C2 and fill down. With available hours in F2, calculate the excess requirement:
=SUM(D2:D3)-$F$2
Required time exceeds availability by 415 − 400 = 15 hours. The load ratio is 415 / 400 = 103.75%, or 103.8% rounded to one decimal place. Retain unrounded calculations.
Change only pump demand from 500 to 560 units. Required pump output becomes 560 + 100 − 120 − 40 = 500 units. The additional 60 units require 60 × 0.50 = 30 hours. This shows the capacity consequence of a demand revision without pretending the factory has already agreed to produce it.
The production capacity comparison extends this check across sites. For components, pass the approved output quantities to material demand forecasting, keeping that requirement separate from customer demand.
Upload a file or Google Sheet containing demand, inventory, scheduled supply, time standards and available capacity; Covirage maps the columns, and its tools compute and check the comparisons. The external AI model explains the results with every figure traced to its rows. Create a free Covirage account, set up your business and bring a sample of your own data; creating the account takes about a minute.
See Covirage for industrial manufacturers for the industry context.
Demand forecasting estimates customer requirements. Production planning determines the output needed to serve those requirements after inventory, existing supply and timing are considered. A forecast can be reasonable while the resulting production plan remains infeasible because materials or constrained work centers are unavailable.
Use finished inventory available to meet the stated demand, at the correct product revision and site. Exclude stock on hold or already committed outside that demand. Keep work in process separate unless its expected completions are included once as scheduled supply.
Yes. Put demand, usable opening stock, scheduled supply and target closing stock on each product-period row. Calculate the positive remaining requirement with MAX, then multiply it by the appropriate standard processing time. Check stock balances and capacity by period rather than relying on an overall total.
No. A capacity check identifies whether required work fits the supplied time allowance at a work center. A feasible schedule must also respect operation sequence, materials, staffing, setup requirements and due dates. Operations must approve those constraints before releasing production.