Quantity takeoff
A quantity takeoff answers the question "how much has to be built?". Working from the architectural, structural and MEP drawings, you measure the quantity of every item: square meters of wall and floor, cubic meters of concrete and excavation, linear meters of pipe, kilograms or tons of rebar, and counts of doors and windows. Each quantity is expressed in the unit of measure of the item that will consume it.
The takeoff comes before the estimate: first you quantify (pull the amounts off the drawing) and then each quantity is multiplied by the unit price of the matching item to reach its cost. An error in the takeoff carries through to the entire estimate, which is why the backup for each quantity — the measurement sheet, or backup calculation — records where it came from (which gridline, level or section of the drawing).
Traditionally the takeoff is done by hand on printed drawings, or by measuring in CAD (DWG/DXF) and dumping the results into a spreadsheet, which is slow and prone to omissions. Today it is automated by extracting the quantities directly from the digital drawing (DWG, PDF or image) to speed up the process and reduce errors, the way Matterial does.
Example
For an 8 × 5 m slab that is 12 cm thick, the takeoff yields 40 m² of area and 4.8 m³ of concrete (8 × 5 × 0.12). Those 4.8 m³ are then multiplied by the unit price of concrete to get the cost of the line item.
| Material | Unit | Quantity |
|---|---|---|
| Concrete f'c=250 | m³ | 148.5 |
| Rebar | ton | 12.4 |
| Standard formwork | m² | 620 |
| Block wall | m² | 385 |
| Concrete slab-on-grade | m² | 210 |
Frequently asked questions
Is a quantity takeoff the same as quantification?
In practice, yes. Quantification is the act of measuring the quantities on the drawing, and the quantity takeoff is the result — the full set of quantities obtained. On site the two are used almost interchangeably.
How do you take off quantities from a drawing?
You identify each item (walls, slabs, columns, MEP) and measure its quantity in the corresponding unit: areas and volumes from dimensions, lengths from runs, and pieces by count. Each result is backed up by its measurement sheet. It can be done by hand, in CAD, or automatically from the digital drawing.
What units are used in a quantity takeoff?
The unit of each item: square meters (m²) for walls and floors, cubic meters (m³) for concrete and excavation, linear meters (lm) for pipe and tie-columns, kilograms or tons for rebar, and each (piece) for elements such as doors or windows.