The maker's costing glossary
Bill of Materials (BOM)
The itemized list of everything that goes into a product.
A bill of materials lists every material and component a product uses, with quantities. Costing from a BOM — quantity × unit cost, line by line — is how you get a repeatable, accurate unit cost instead of a gut-feel number that drifts every time you quote.
Why it matters
A BOM turns pricing from guesswork into arithmetic. Without one, you re-estimate every time and forget small components; with one, the cost is exact, repeatable, and instantly updatable when a supplier price changes. It's also what lets you scale — the same recipe reprices for a batch of 10 or 200.
How to calculate it
List each material and the quantity the product consumes, multiply each by its unit cost, and sum. Add labor and machine time separately to reach full cost.
Example
A candle BOM: 200 g soy wax, 16 g fragrance, 1 wick, 1 vessel, 1 label — each line costed by quantity × unit price gives an exact material cost every time.
In practice
Makers who write down BOMs stop 'forgetting' the wick, the clasp, or the interfacing — the small parts that quietly erode margin when estimated from memory.
Common mistakes
- Leaving out small, cheap components that add up across a batch.
- Not updating BOM quantities when a design changes.
- Estimating material use instead of measuring it once and recording it.
How CrafterBy handles it
In CrafterBy a product's recipe is its BOM: add materials with quantities and the unit cost is exact — and reprices automatically when any material's price changes.