Although I might be added to the terrorist watch list for the title of this blog, knowing how to make a BOM (not bomb) is very important. For those of you not familiar with the term, BOM stands for Bill of Materials. Essentially, when you are in the design phase of a project, you want to account for the materials you will need, which helps you to better budget your project and purchase proper quantities. Being a Manufacturing Engineer, I am very familiar with BOMs, but it wasn’t until my dad made one up for our built-in office shelving unit that I realized just how useful they could be at home. Since BOMs are so simple to set up, I would encourage you to make one before starting your next DIY home improvement project.
A basic BOM needs to give you a list of materials with quantities needed and the unit cost. You then want to add the extended cost per line item (quantity * unit cost), and a project total at the bottom (sum of all extended costs). Taxes add up, so don’t forget to factor in your local tax rate for a more accurate total.
If you are purchasing materials from multiple sources, you may want to reference where each item will be purchased and add their part number (PN) for easy reference.
Shipping charges are another thing to consider, but since shipping charges aren’t typically known until you check out (or even after in some cases) I usually just leave a buffer in my budget to account for any I might have. Having a BOM will also help to reduce shipping charges, because you know what you need upfront, and can hopefully condense what needs to be ordered into as few shipments as possible.
I put together this BOM Template in Excel to help you get started.
Don’t forget the small stuff
Nails, screws, and glue add up, and if you don’t factor in at least an estimate of what you will need, you will be in for a surprise. Some stuff you just won’t know until you get started, but I suggest taking your best guess and adding it to your BOM in the design phase.
Update your BOM
As your project changes (as mine always do), don’t forget to update your BOM. Save each major update as a separate document (or separate tab in Excel), so you can reference prior versions as needed. Also, you can easily see the price impact that a mid-project change will have, helping you to decide if the change can be justified. When you finish your project, you can keep your BOM and all project receipts together for easy reference.
I hope you found this blog helpful and please feel free to leave any comments or further BOM making suggestions.