Free tools BOM
For each line of the bill of materials, multiply the quantity per finished unit by the number of units planned. That gives gross requirements. Subtract stock on hand to get net requirements, which is what you actually purchase. This is the core of material requirements planning, done at small business scale.
Gross requirement = per unit BOM quantity × planned units; net requirement = gross − stock on hand
A candle BOM lists 200 g wax, 20 ml fragrance, 1 wick and 1 jar per unit. The plan is 150 units. Stock is 18,000 g wax, 900 ml fragrance, 400 wicks and 120 jars.
Result. Net requirements are the purchase order. Wicks appear in the plan but not in the order, because stock already covers them.
Enter your BOM lines, the units they produce, your stock, and the production target. The calculator returns gross requirements, net requirements and the cost of covering the gap.
200 g per unit30000 g needed for 150short 12000 g
20 ml per unit3000 ml needed for 150short 2100 ml
1 pcs per unit150 pcs needed for 150enough in stock
1 pcs per unit150 pcs needed for 150short 30 pcs
This runs entirely in your browser and nothing is saved. Makeable keeps the same calculation running against your live stock, so it re-answers itself every time an order arrives. Start free or read how to calculate production capacity.
Material requirements planning has a reputation for complexity, but the arithmetic at the heart of it is a multiplication and a subtraction per BOM line. Full MRP systems add scheduling, work orders, routings and multi site logistics on top, which is why they cost what they cost.
A small producer with a handful of products usually needs the arithmetic and the alerts, not the scheduling layer. That is the gap Makeable is built for.
Requirements planning is only as accurate as the BOM. Record quantities in the unit you purchase, keep one unit per material across all recipes, and update the BOM when the recipe changes rather than remembering the difference.
Version the BOM if the recipe evolves, so a run planned last month can still be explained by the data that produced it.
Makeable is production capacity and inventory planning software for small businesses that make physical goods from recipes or bills of materials. It stores your materials and recipes, keeps stock current as orders arrive, and runs the calculation on this page continuously rather than on request, so the answer to "can I make this?" is always current.
You can start on the free plan with three products and fifteen materials, see how the production engine works, or compare plans and limits.
Gross requirement is total consumption for the planned quantity. Net requirement subtracts stock on hand, and is the amount you actually need to buy.
For a small producer with a few products and single level BOMs, yes. Once you need routings, work orders and multi site scheduling, a full MRP system becomes worth its cost.
Makeable stores each product's BOM or recipe, keeps material stock current, and continuously recalculates capacity, bottlenecks and net requirements as orders arrive.
For information and estimates only. Makeable's formulas, batch limits and margin calculations are mathematical estimates based on your inputs. They are not certified accounting, financial, pricing or tax advice. You are solely responsible for setting your own wholesale and retail prices, ensuring profitability, and checking cost calculations before committing money.