Concrete volume
Estimate slabs, solid cylinders and hollow tubes; compare bag purchases with bulk concrete.
How this works
Slab volume = length × width × thickness. Solid cylinder = π × outer diameter² / 4 × height. Hollow cylinder = π × (outer diameter² − inner diameter²) / 4 × height. Multiply by identical quantity, add allowance, then divide by mixed bag yield and round up. 1 yd³ = 27 ft³; 1 ft³ = 0.028316846592 m³.
Example
The illustration may use different inputs from the reproducible default inputs listed below.
A 12 ft × 10 ft slab, 4 in thick, contains 40 ft³. With 10% allowance, order volume is 44 ft³ (1.63 yd³). At 0.6 ft³ mixed yield per bag, round 73.33 up to 74 bags. For a cylinder use outer diameter and vertical height; for a tube also enter the inner diameter.
- Shape
- Rectangular slab
- Dimension units
- Feet; depth in inches
- Slab length / outer diameter
- 12 ft or m
- Slab width / inner diameter
- 10 ft or m
- Thickness / cylinder height
- 4 in or cm
- Identical shapes
- 1 count
- Extra allowance
- 10 %
- Mixed yield per bag
- 0.6 ft³ or m³
- Bag yield units
- Cubic feet
- Price per bag
- 0 USD
- Bulk price per cubic yard
- 0 USD/yd³
- Concrete including allowance
- 1.63 yd³
Choose bags OR bulk, not both. A zero entered price means cost is not supplied. Use actual mixed bag yield. Cylinder height is the thickness/depth field; diameter uses the length field. Tube inner diameter uses the width field.
Scope and assumptions
Quantity arithmetic only. This does not design strength, reinforcement, foundations, loading, forms or code compliance. Product yield, delivery minimums, settlement and site waste vary; verify your order with the supplier. Dimension unit selectors change interpretation, not stored numbers.
Related quantity-calculation reference