Before anyone can order a single transmitter or valve, someone has to list exactly what the project needs. That list is the material take off.
This guide covers what an MTO contains, the instrument categories it must cover, how it gets built, and how it differs from a BOM or BOQ.
A material take off turns a design into a shopping list. Get it wrong, and the plant either runs short on site or pays for parts nobody needed.
We will cover what it contains, the instrument categories it must list, its three project stages, how it gets built step by step, and how it differs from a BOM and a BOQ.
What Is a Material Take Off (MTO)?
A material take off is a detailed inventory of every material and component an instrumentation project needs.
It supports four jobs at once: cost budgeting, procurement ordering, project scheduling, and confirming that construction has what it needs.
Every line on a good MTO is cross referenced back to the project's P&ID, so nothing gets counted twice or left out.
An MTO is never treated as a fixed document. It must flex as the project moves from design through construction and commissioning.
Instrumentation engineers usually prepare the first draft, working closely with the procurement and cost estimation teams who will act on it.
It draws directly from instrument datasheets and hook up drawings, so any change on those documents must also be reflected on the take off.
On a large plant, hundreds of individual instruments can appear on one MTO, so consistent naming and numbering matters as much as the numbers themselves.
What Information Does an MTO Document Contain?
A well built MTO line item always answers the same five questions, whatever instrument it describes.
Here is what one real line item might look like once every field is filled in.
Description: Pressure Transmitter, 4 to 20 mA with HART
Quantity: 6
Specification: Range 0 to 40 bar, ATEX rated, 316 SS wetted parts
Vendor: Approved vendor list, Item 3
7 Instrument Categories Every MTO Must Cover
Instrument scope on a plant is wide. Grouping it into seven categories keeps the take off organised and complete.
Certifications matter here too. Any device going into a classified area needs its protection method confirmed before it is added to the list.
A large process unit can easily carry several hundred tagged instruments across these seven categories, which is exactly why consistent grouping matters.
Missing even one category during the early design review tends to surface late, usually as an unplanned purchase order during construction.
Additional MTO Line Items Often Missed
These items rarely appear on a first draft, yet leaving them out causes real delays during construction.
The Three Stages of a Material Take Off
An MTO is not written once. It matures through three recognised stages as the design gets more detailed.
| Stage | Design Basis | Typical Use |
|---|---|---|
| Preliminary | Approved P&ID and plot plan only | Early budget number and request for quotation |
| Secondary | Detailed 3D model or isometric drawings | Firm purchase orders and updated cost tracking |
| Final | Fully approved isometrics and as built data | Closing out procurement with no leftover stock |
Skipping straight from preliminary to final rarely works well. The secondary stage is what catches most of the quantity errors before they become expensive.
How an MTO Gets Built: Step by Step
Behind every finished MTO is the same six step process, whichever engineering team is running it.
Common Material Take Off Mistakes to Avoid
Most MTO problems on site trace back to one of these five recurring mistakes.
Software Tools Commonly Used to Prepare an MTO
Most engineering teams no longer build an MTO by hand in a spreadsheet alone, though smaller projects still can.
- 3D modelling software such as PDMS or E3D generates real pipe lengths and fitting counts straight from the model during the secondary stage.
- Tag based engineering databases like SmartPlant Instrumentation or Intools track every instrument tag against its specification sheet automatically.
- Spreadsheet templates remain common for a preliminary MTO or on smaller brownfield projects with a limited instrument count.
- ERP and procurement systems take the final MTO and turn it into actual purchase orders sent to approved vendors.
Whatever tool is used, the underlying discipline stays the same. Every quantity still has to trace back to an approved drawing.
Every revision of the MTO should also carry its own version number and issue date, printed clearly on the document header.
Without that, procurement can easily place an order against an outdated copy, ordering parts the latest design no longer needs.
Material Take Off vs BOM vs BOQ: What Is the Difference?
These three documents are often confused, but each one answers a different question at a different point in the project.
| Document | Main Purpose | Used By |
|---|---|---|
| MTO | Lists everything that must be purchased to build the design | Procurement and cost engineers |
| BOM | Lists components needed for one specific fabrication or drawing | Site fabricators pulling stock from the warehouse |
| BOQ | An early, preliminary scope of material for tendering | Bidding contractors before detailed design is finished |
In short, the MTO drives procurement, the BOM supports fabrication on site, and the BOQ exists to let contractors bid on the work.
Why MTO Accuracy Matters for Procurement and Cost
A tight, well checked MTO protects the project budget and the construction schedule at the same time.
The difference between a careful list and a rushed one shows up months later, on site.
An Accurate MTO Delivers
- Materials arrive on site exactly when construction needs them.
- Procurement can negotiate better prices on known, fixed quantities.
- Change orders during construction are easy to track and cost.
A Sloppy MTO Causes
- Overordering that ties up cash in unused spare instruments.
- Underordering that stops construction crews mid installation.
- Disputes with vendors over specifications that were never clear.
Tracking Long Lead Items on the MTO
Not every line item on an MTO carries the same urgency. Some instruments take months to manufacture and ship.
Custom control valves, large analyzers, and specially rated transmitters for extreme pressure or temperature service often fall into this category.
A good MTO flags these long lead items separately, with their expected delivery time noted right beside the quantity and specification.
Procurement then releases purchase orders for these items first, well before the rest of the list is even finalised.
Missing a single long lead item on an early MTO pass can push back the whole project schedule by months, not days.
Watch: Material Take Off Explained
Material Take Off Questions Engineers Ask
Related Articles on This Site
- Instrumentation Engineers Guide
- Instrument Loop Checking Procedure
- Types of Instrumentation
- Signals in Instrumentation: AI, AO, DI, DO
- Instrumentation Calibration and Troubleshooting Guide
External References
What We Learn Today
- A material take off is a detailed, cross referenced inventory covering seven instrument categories, from sensors and valves to junction boxes and cabling.
- It matures through three stages, preliminary, secondary and final, and stays flexible as the design changes right up to construction.
- An MTO differs from a BOM and a BOQ in purpose and audience, and accuracy at every stage protects both budget and schedule.