Concrete Calculator

How to estimate concrete volume

1. Choose rectangular or round. Enter the space actually filled, with a unit for each dimension. Round pours use full diameter, not radius. No thickness is recommended or filled in for you.
2. Read the estimated volume in cubic metres, cubic yards, cubic feet or litres. Open Planning options only if you need identical pours, a chosen extra allowance or bags. The initial count is 1 and extra is 0%.
3. For bags, enter the mixed concrete yield stated on this product's label or data sheet and its matching volume unit. Check the result and assumptions in Calculation details; this is not a guaranteed order quantity.

Understand the dimensions and mixed yield

A rectangular pour uses length × width × thickness. A solid cylindrical pour uses π × (diameter ÷ 2)² × depth. Each length is converted to compatible units before calculation.

Multiply one pour's volume by the number of identical pours, then apply the selected extra percentage once. No automatic waste, shrinkage, compaction or delivery allowance is added.

Bag yield is the volume of concrete produced after mixing as the manufacturer specifies. Cement alone, dry powder volume and bag mass are different quantities. Products and stated yields vary; there is no universal conversion from kilograms or pounds to concrete volume.

The approximate bag count uses the unrounded total and the entered yield, with whole bags rounded up. Display rounding never determines bag count. Actual product yield, measurements and site conditions can still change the amount needed.

Worked quantity examples

A rectangular pour measuring 4 m × 3 m × 10 cm has a volume of 1.2 m³. A chosen 10% extra changes the total to 1.32 m³. These dimensions and the allowance are example inputs, not design advice.

A 10 ft × 6 ft × 4 in rectangular pour is 20 ft³, about 0.741 yd³. With an entered mixed yield of 0.6 ft³ per bag and no extra, the estimate is 34 bags. At 0.45 ft³ per bag, it is 45 bags. Use the yield for your actual product.

A solid round pour with diameter 1 m and depth 10 cm has volume π/40 m³, displayed as about 0.0785 m³. It does not subtract a post or any other occupied space.

Quantity estimate, not a construction design

The calculator assumes the entered rectangular or solid cylindrical space is filled with concrete. It does not subtract posts, reinforcement or inner voids, combine different shapes, account for uneven ground or model delivery rules. Different pours can be calculated separately.

It does not choose thickness, concrete type, reinforcement, mix proportions or a suitable extra allowance, or assess structural, site, code or safety requirements. Measurements, yield and conditions affect the amount actually needed. Follow the applicable product and project requirements.

Browser-side calculation

The calculator performs arithmetic in your browser and does not intentionally upload or save these inputs. Copy result uses the clipboard only when requested. Normal site services and consent settings remain separate.