Concrete wall volume calculator

For cast concrete walls where rectangular full-depth openings remove material from an otherwise solid wall.

Length, height and thickness

The outside rectangular wall envelope and its constant thickness.

Openings

Width, height and count for each opening group. Enter non-overlapping rectangles within the wall.

Leave the opening list empty for a solid wall, or add groups of repeated doors and windows.

• Gross volume, deducted volume, net concrete, extra and total required.

One wall with one separate door opening.

Net = (length × height − sum of opening areas) × thickness. Required volume before display rounding is 2.7522 m³.

Ready-mix planning uses the required volume and a truck capacity you enter. Bagged mix uses the finished yield of one bag; bag weight alone does not determine it. Whole bags and loads round up. Optional cost uses your price per volume or per bag.

Bag-count example for a separate slab: 0.660 m³ divided by an assumed yield of 0.020 m³ per bag gives 33 bags. This yield is an example input, not a specification for every 40 kg or 50 kg bag. Check the selected product.

Metric and imperial entry are supported. In these examples, lengths are converted to metres before multiplication; displayed volumes are rounded to three decimals. The arithmetic retains the unrounded value.

The extra percentage is a chosen allowance for this estimate. It is not a required building-code value. Geometry estimates quantity; it does not select concrete strength, foundation depth or reinforcement.

Opening positions are not entered. Areas are added, so overlapping rectangles would be deducted twice. Recesses that do not pass through the wall need separate volume treatment.

Are lintels added separately?

The wall envelope already includes the region above each opening. Add only concrete outside that envelope or of a different thickness.

Can I use it for brickwork?

Use Brick/Block Wall for unit counts, courses and mortar estimates.