Material takeoff
A material takeoff, or MTO, is made by an estimator from the bid drawings. Its purpose is to price the job. It lists each material with a quantity and a unit. It is as detailed as the bid needs and no more.
Bill of materials
A bill of materials, or BOM, is made after you win the job. Its purpose is to buy and build. It comes from approved shop drawings or from the manufacturer's engineering. It lists exact part numbers, sizes, finishes and hardware.
Side by side
- When. The MTO is made before the bid. The BOM is made after award.
- Source. The MTO comes from bid documents. The BOM comes from approved submittals and field measurements.
- Detail. The MTO says 12 backstops of one type. The BOM lists every part for each one.
- Who makes it. An estimator makes the MTO. A project manager, a detailer or the manufacturer makes the BOM.
- Who uses it. Estimating and sales use the MTO. Purchasing, the shop and the field use the BOM.
Why you should not order from the takeoff
The bid drawings are not the final word. Submittals get comments. Field dimensions differ from the plans. Addenda and change orders move things. An order placed from the bid takeoff can bring the wrong size or the wrong count. Build the BOM from the approved documents.
How one feeds the other
- The takeoff sets the bid quantities.
- The estimate prices them.
- After award, the takeoff becomes the starting list for submittals.
- Approved submittals and field measurements become the BOM.
- The project manager compares the BOM to the takeoff.
That last comparison matters. When the BOM is larger than the takeoff, find out why at once. The cause is either a takeoff error or a change you should be paid for.
In some industries, MTO and BOM are used for the same list. In building construction, most people keep the split above. Ask what the other person means.
Bidding and estimating · Updated 11 Nov 2026