Quantity Takeoff (Work and Material Quantities)
Doing a takeoff means going through the drawings and specifications to pull out "how much there is of each thing": square meters of wall, cubic meters of concrete, tons of steel, light fixtures by the piece. Each item in the schedule is measured in its own unit, and the detail of the calculation is documented in the measurement sheet (with its geometric operations: length × width, areas, volumes).
It helps to distinguish two scopes. The construction quantity takeoff measures the quantities of the work items to be executed (the "what gets done": excavation, formwork, concrete placement), which are then priced with unit rates to build the cost estimate. The material takeoff, or material quantity survey, calculates the amounts of cement, rebar, block, and so on needed to carry out those items; it draws on the consumption rates from the unit price analysis and leads to the material breakdown, the requisitions, and the purchase orders.
The takeoff is the foundation of all cost control: if the quantities are measured wrong, the estimate, the purchasing, and the progress billings all carry the error forward. That is why the resulting "quantity of work" must be traceable back to the drawings. Traditionally it is done by measuring printed or CAD drawings and dumping the results into a spreadsheet; today it is also done with quantity takeoff tools that measure directly on the digital drawing and tie every quantity to its work item.
Example
For a slab 8 m × 5 m and 12 cm thick, the construction quantity takeoff yields 40 m² of slab and 4.8 m³ of concrete. With a steel consumption rate of 85 kg/m³, the material takeoff estimates 408 kg of rebar for that slab.
| 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
What is the difference between a quantity takeoff and volumetric measurement?
Volumetric measurement focuses on obtaining volumes and geometric quantities from the drawings (m², m³, linear lengths). The quantity takeoff is the broader process that organizes those quantities by work item and by material, leaving them ready to estimate and to buy.
How is a material takeoff done?
You start from the work quantities per item and multiply them by the material consumption rates in each unit price analysis (for example, kg of steel per m³ of concrete). The result is the material breakdown, which is grouped by material to generate requisitions and purchase orders.
What units are used in a takeoff?
The unit of measure of each item: square meters (m²) for walls, plaster, and floors; cubic meters (m³) for concrete and excavation; tons or kilograms for steel; and pieces (ea) for discrete elements such as doors or light fixtures.