Percentage vs quantitative BOMs: building a formula by percent or by weight

A formula can be written two ways: as percentages — each ingredient as a proportion of the whole — or as quantities, the absolute amount of each per unit or per batch. Both are valid, both are used, and you constantly need to move between them. Getting the conversion right is essential, because an error scales across a whole batch. Here's how percentage and quantitative BOMs work, and why the conversion matters.

The percentage BOM

A percentage formula expresses each ingredient as a percent of the total, summing to 100%. It's the natural way to design and think about a product — the composition independent of batch size. It scales effortlessly: the percentages are the same whether you make one kilogram or one tonne. Formulators often work in percentages because it captures the product's identity without committing to a quantity.

The quantitative BOM

A quantitative formula expresses each ingredient as an absolute amount — milligrams per capsule, kilograms per batch. It's what you actually weigh out and buy: the percentages turned into real quantities for a specific unit or batch size. The quantitative BOM is operational; it's what the factory and the purchasing team work from. You can't make or buy against percentages — you need the amounts.

Moving between them

The two are tied by the batch or unit size: quantity equals percentage times the total. So a percentage formula plus a batch size gives the quantitative BOM, and a quantitative BOM divided by the total gives the percentages. You move between them constantly — design in percent, produce in quantity; scale a batch up by recomputing quantities from the percentages. The conversion is simple arithmetic, but it's everywhere.

Why the conversion has to be exact

Because the conversion scales across a batch, an error multiplies. A small mistake converting a percentage to a per-batch quantity, times a large batch, is a lot of mis-weighed material — expensive, and potentially a failed product. And rounding has to be handled carefully so the quantities still sum correctly and the percentages still reflect the real amounts. This is exactly the arithmetic that's error-prone by hand and reliable when computed.

Keep both views from one source

The clean approach is to hold the formula once and let the software present it either way — percentages for design, quantities for any batch size — computing each from the same source. Then you design in percent, produce in quantity, and scale to any batch, with the conversion always exact and the two views always consistent. No manual recomputation, no drift between the percentage formula and the batch sheet.

This is general information, not regulatory or legal advice. Confirm requirements for your specific products and process with a qualified expert before relying on a general summary.

Where Lemoniq fits

Lemoniq holds the formula once and presents it as percentages or as quantities for any batch size — computing each from the same source with exact conversion — so you design in percent, produce in quantity, and scale to any batch without manual recomputation or drift.

The takeaway

A formula lives as percentages (for design and scaling) and as quantities (for production and purchasing), and you move between them constantly — a conversion that has to be exact because it scales across a batch. Holding both views from one source keeps the conversion right and the views consistent. That's the foundation of a usable BOM.

Lemoniq gives you percentage and quantitative views of one formula, with exact conversion at any batch size. See how it works