Three terms appear repeatedly in EPC (Engineering, Procurement and Construction) projects — Material Take-Off (MTO), Bill of Quantities (BOQ) and Bill of Materials (BOM) — and they are frequently confused, misused or treated as interchangeable. In practice, each document serves a distinct purpose, is prepared by a different discipline and is consumed by a different party in the project chain. Using the wrong document for the wrong purpose causes procurement errors, cost overruns and construction delays.
This guide explains each term precisely, describes how each is prepared, and clarifies when each is the right tool for the job — with particular reference to oil & gas, petrochemical and industrial construction projects in Saudi Arabia and the wider GCC.
Material Take-Off (MTO)
An MTO is a systematic list of all materials required to construct a defined scope of work, extracted directly from engineering drawings and specifications. The MTO is produced by the engineering team — usually the discipline engineers (piping, structural, mechanical) — by measuring quantities from IFC (Issued for Construction) drawings.
A typical piping MTO includes:
- Pipe — material, size, schedule, quantity in linear metres per isometric drawing
- Fittings — elbows, tees, reducers, flanges — by type, size, rating and material
- Valves — tag number, size, type, end connections, body material, trim, actuation
- Gaskets, bolts, nuts — by flange class and count
- Supports and clamps — type and quantity
A structural MTO extracts steel section profiles, plate thicknesses, grades and lengths from structural drawings and section schedules.
Bill of Quantities (BOQ)
A BOQ is a cost document that lists the quantities of materials and work items from the MTO and adds unit rates and total costs. In Saudi Arabia and the GCC, BOQs are issued as part of tender packages so contractors can price a defined scope of work consistently. They are typically prepared by the client's cost engineering or quantity surveying team, sometimes with input from the PMC (Project Management Consultant).
A typical BOQ for a structural package includes:
- Item description (e.g., "Supply and install CS pipe, 6" SCH 40, ASTM A106 Gr.B")
- Unit of measurement (LM, NR, TON, M2)
- Estimated quantity
- Unit rate (filled in by the tendering contractor)
- Total amount
The BOQ allows the client to compare bids on a like-for-like basis and forms the basis of the contract value. Variations during construction are priced against the BOQ rates. BOQs are also used for progress payment claims — the contractor invoices based on the percentage of each BOQ line item completed and verified.
Bill of Materials (BOM)
A BOM is a hierarchical list of all parts, sub-assemblies, raw materials and components needed to manufacture or assemble a specific product or equipment item. It originates from the design — typically from the CAD or 3D modelling environment — and is the primary input for manufacturing planning and shop procurement.
In mechanical equipment fabrication (pressure vessels, heat exchangers, tanks, skids), the BOM includes:
- Shell plates: material grade, thickness, quantity and net dimensions
- Head/end caps: type, material, thickness, formed diameter
- Nozzle neck pipe, flanges and reinforcing pads
- Internal components: baffles, vortex breakers, ladder rungs, agitator shaft
- Fasteners: stud bolt and nut specifications per connection
- Gaskets and seals
- Nameplates and code stamps
The BOM is referenced during workshop fabrication and inspection — not during field construction. It differs from an MTO in that it describes what goes into a single item of equipment, whereas an MTO covers all materials across a field installation.
Which Document Do You Need?
- Planning material procurement from IFC drawings → MTO
- Issuing a tender for construction work → BOQ
- Ordering material to fabricate a piece of equipment → BOM
- Tracking construction progress for payment → BOQ
- Populating a spare parts register → BOM
SLETEC prepares MTOs, BOQs and BOMs for piping, structural, mechanical and civil scopes. Our MTO/BOQ/BOM preparation service is used by EPC contractors and owner-operators in Saudi Arabia and India to support procurement, tendering and construction management.