Plan a Whole Concrete Job, Not Just One Shape
A real project can involve several separate pours: a slab, a strip footing and repeated post holes. Calculating them independently makes it easy to lose a quantity or apply an allowance more than once. This planner keeps every measured volume in one list, adds them together, then applies one allowance to the combined job.
Worked example: shed slab and six post holes
A 3m × 3m × 0.1m slab has a measured volume of 0.900m³. Six circular holes, each 0.3m in diameter and 0.6m deep, add approximately 0.254m³. The combined measured volume is approximately 1.154m³. With a user-selected 10% allowance, the planning quantity is approximately 1.270m³, or 138 of the referenced 20kg bags after rounding up.
Use “Load worked example” to inspect that calculation, then replace every value with measurements from your own project.
How each shape is calculated
Rectangular pours use length × width × depth. Circular pours use π × radius² × depth. Quantity multiplies that result for repeated identical pours. The planner sums the measured volumes before applying the selected project allowance.
For post holes, the planner subtracts the round or square post volume over the entered hole depth, using the same formula as the post-hole calculator. Transferring a calculation carries its measurements and quantity, before allowance. When adding it to a draft, the draft's allowance applies to the whole job; allowances are never stacked.
What saving and sharing do
“Save on this device” stores the project locally in your current browser. “Copy share link” places the project values in the link itself, so another person can review the same list without an account or server upload. Printing produces a compact job summary for checking measurements or discussing an order.
Use the result as a planning estimate
The planner does not choose thickness, footing size, hole depth, concrete strength, reinforcement or structural details. Use dimensions from the relevant plans, manufacturer or qualified professional. Check the exact product yield and obtain a current supplier quote before ordering. See the complete methodology and primary sources.