Formula vs bill of materials
A bill of materials is a list of countable parts: one top, four legs, twelve screws. A formula is a set of proportions that add up to a whole: 62 % habanero, 21 % vinegar, 9 % onion, 5 % salt, 3 % garlic. Most manufacturing software is built for the first and asked to do the second, which is where the friction starts.
What proportions give you that a parts list cannot
Section titled “What proportions give you that a parts list cannot”Scaling is arithmetic, not multiplication of units. A formula at 62 % habanero is 12.4 kg in a 20 L batch and 62 kg in a 100 L one. There is no “1.24 legs” problem, because the line was never a count.
The total is the thing being made. Percentages describe one kilogram of product. Change the batch size and nothing about the recipe changes. In a parts list, changing the quantity means editing every line.
Yield is expected. Cooking off water, trimming, absorbing into equipment: a formula’s output is smaller than its input, and by a rate you learn from real batches. See yield. A parts list assumes four legs go in and four legs come out.
Substitution is by function. Swap one acidifier for another at the same percentage and the formula still balances. Swap a screw for a different screw and you edit a line item.
Where the two meet
Section titled “Where the two meet”Real products need both. A 250 ml jar of sauce is a formula (the sauce) plus counted items (the jar, the lid, the label). BatchDash keeps them as different things on purpose: the sauce is a formula costed per kilogram, and the jar is a product whose packaging is counted per unit.
That is also why an ingredient can be counted rather than weighed when that is how it really arrives: eggs come by the dozen even inside a mass-based recipe.
The practical test
Section titled “The practical test”If someone asks “what is this made of” and the honest answer is a set of percentages, you have a formula. If the honest answer is a list with quantities of one, you have a bill of materials. Software that only models the second will make you carry the first in a spreadsheet beside it.