Preparing a Bill of Materials
A bill of materials (BOM) is a purchasing list: a structured record of the items you are asking suppliers to price and supply for one project. It is not a quantity takeoff, an engineering or design document, or a purchase order. Its purpose is to describe each requested item clearly enough that quotes can be prepared and compared on the same basis.
Required data points for each line
A clear bill of materials gives every line the same core information, so quotes can be prepared against one consistent request. Use the points below as the column set for your purchasing list.
Project reference
Keep one project reference across the whole list and all related messages, so every line and revision traces back to the same request.
Unique item IDs
Give each line its own ID and do not reuse it. Questions, alternatives and quote lines can then refer to one exact item.
Product and specification
Describe the product and cite the governing specification or standard as written in your project documents.
Quantity and unit
State the quantity together with its unit of measure. A number without a unit can be read in more than one way.
Dimensions, grade, finish
Record size, grade and finish in separate fields where they apply, rather than combining them into one free-text description.
Drawing revision
Note the drawing number and revision each line was taken from, so changes between revisions can be identified.
Required documents
List any documents your project requires with the material, such as certificates or data sheets, against the relevant lines.
Destination
Identify where the material needs to go. If lines go to different locations, record the destination per line.
Requested date
Give the date you are requesting. It is a request, not a confirmed date, until it is confirmed in a quote.
KEEP THEM SEPARATE
Optional & Unresolved
Optional lines are items you may want priced but have not committed to, such as alternates, spares or a possible later phase. List them in their own group, below the core lines, and label each one clearly as optional so it is never read as part of the base request.
Unresolved details are open questions: a grade not yet confirmed, a finish awaiting approval, or a dimension pending the next drawing revision. Record each one against its item ID with a short note of what is still open, rather than guessing a value.
Keeping primary lines, optional lines and open questions apart makes it easier for everyone reviewing the list to see what is firm, what is a choice, and what still needs a decision from the responsible reviewer.
Practical template example
Use these columns as a starting structure for your own purchasing list. The rows are intentionally blank: enter your project's own IDs, specifications, quantities, units, revisions and destinations, and list optional lines and unresolved details separately.
ID
Description
Specification
Qty
Unit
Revision
Destination
Add further columns for grade, finish, dimensions, required documents and requested date where they apply to your project.