Six inches is 0.5 ft. That small conversion is often the difference between a sensible concrete estimate and a result twelve times too large. In the Whatson Concrete Volume Calculator, depth follows the selected measurement unit.
For a slab, the measured volume is length × width × depth. For a cylinder, it is π × radius² × depth. The quantity field repeats the whole element; the ordering allowance is applied after that.
Start with the pour, not the building area
Measure the actual concrete element. A room’s floor area is not automatically the size of a footing or a roof slab. Exclude spaces that will not receive concrete, or calculate separate rectangular sections and combine their measured volumes yourself.
Select slab or cylinder before entering dimensions. The interface hides dimensions that do not apply to the chosen shape. A cylinder uses diameter, so there is no need to halve your measurement before entering it.
Reproduce a 150 cft slab
Choose feet. Enter length 20, width 15, depth 0.5 and quantity 1. With a 5% ordering allowance, the checked results are:
| Item | Quantity |
|---|---|
| Measured concrete | 150 cft, about 4.25 m³ |
| Order volume | 157.5 cft |
| Concrete to order | about 4.46 m³ |
The tool converts the measured volume to cubic metres internally. The order figure includes the allowance; it is the one to compare with a supplier’s delivery quantity.
Multiple elements need a deliberate choice
Use quantity 4 for four identical cylinders. Do not use it for four different foundations and hope an average dimension will be accurate. For varying shapes, run separate calculations and retain their results.
Neither shape deducts reinforcement or describes complex steps, beams crossing a slab, void formers or irregular foundations. Decide how the takeoff should treat those details with the person responsible for the drawing.
From volume to a quote
The price field expects PKR per m³, not per cft. Convert the supplier’s quote before entering it if their unit differs. Pumping, delivery, small load charges and labour may need separate budget lines.
A concrete volume estimate does not specify strength, water content, reinforcement or curing. Use the approved specification for the pour. The Cement & Concrete Mix Calculator can explain nominal material quantities for an entered wet volume, but its default proportions are not a structural mix approval.