CALCULATION GUIDE
How to calculate mortar and concrete for a project
Measure each area separately, use consistent units and add a reasonable allowance before choosing the supply method.
Concrete volume
Multiply length, width and thickness expressed in metres. For repeated elements, multiply by their quantity. A thickness of 10 cm is 0.10 m.
Mortar by surface area
For screeds and renders, deduct openings and combine the net area with thickness. The number of bags always depends on the manufacturer's declared yield.
Bricks, blocks and joints
Unit dimensions and joint thickness determine both units per square metre and the approximate mortar volume between them.
Allowance and ordering
Five percent is often a starting point for regular geometry. Uneven bases, losses or complex work may justify a larger allowance.
Frequently asked questions
How do I convert centimetres or millimetres to metres?
Divide centimetres by 100 and millimetres by 1,000 before calculating volume.
Why are bags rounded up?
Bags cannot be purchased in fractions and the prepared quantity must cover the full estimate including allowance.
Can I use the result for structural concrete?
Only as a quantity estimate. Strength, mix design and reinforcement must be defined through technical documentation and a qualified professional.
Which yield should I enter?
Use the technical sheet for the exact product and the stated thickness or application system.
