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A brick calculator is useful only when the measured quantity and estimating assumptions match your project. This guide shows how to calculate brickwork volume, estimate bricks, cement and sand, and use Calculate Simply’s brickwork and mortar tools without confusing square feet with cubic feet.
Choose the right brickwork calculator
Our Brickwork and Mortar section includes three measured-volume tools: the 9 inch brick wall calculator, 4.5 inch brick wall calculator and foundation brickwork calculator. Each accepts cubic feet (CFT) or cubic metres (m³). Choose the tool for the work you have measured, then review its editable assumptions.
These tools estimate masonry materials. They do not decide whether a wall thickness, foundation size or mortar specification is structurally suitable. The covered-floor-area House Brick Quantity Estimator is a different early planning method; do not add both estimates for the same work.
Measure brickwork volume before counting bricks
For a rectangular wall, volume equals length × height × thickness. Measure actual masonry thickness, excluding plaster and finishes. When dimensions are in feet, convert inches to feet: 9 inches = 0.75 feet; 4.5 inches = 0.375 feet.
For example, a 20-foot-long, 10-foot-high, 9-inch-thick wall has a gross volume of 150 CFT. A 3 × 7-foot door through that thickness occupies 15.75 CFT. The net brickwork is therefore 134.25 CFT, approximately 3.802 m³. Deduct only the openings in the scope being measured, and avoid double-counting corners or wall intersections.
For a 4.5-inch wall with the same length, height and door, net volume is 67.125 CFT. Thickness changes volume: do not enter the same quantity simply because both walls have the same face area.
Square feet, cubic feet and metric inputs
Square feet describe area; cubic feet describe volume. A 100-square-foot wall is not automatically 100 CFT. Multiply its area by its thickness in feet. With metric measurements, multiply length, height and thickness in metres to obtain m³. One CFT is 0.028316846592 m³. The tools convert the input volume before applying the material method.
How the brick, cement and sand calculation works
The workbook-based 9-inch tool starts with editable assumptions of 13.5 bricks per CFT, a mortar fraction of 25%, a dry-volume factor of 1.3 and a cement:sand ratio of 1:4. These are the website’s estimating defaults, not universal construction standards. Confirm local brick sizes, joints and project specifications.
Dry mortar D = V × mortar fraction × dry factor
Cement bags = D × C ÷ (C + S) ÷ bag volume
Sand CFT = D × S ÷ (C + S)
Here V is masonry volume in CFT; C and S are cement and sand parts by volume. The default bag volume is 1.25 CFT and the assumed bag mass is 50 kg. A different bag size or conversion assumption needs different settings. A 1:4 estimating ratio is not itself a mortar performance specification.
Worked example: materials for 100 CFT
Using the 9-inch calculator’s defaults, dry mortar is 100 × 0.25 × 1.3 = 32.5 CFT. Cement is 32.5 ÷ 5 ÷ 1.25 = 5.2 bags, sand is 32.5 × 4 ÷ 5 = 26 CFT, and bricks are 100 × 13.5 = 1,350 pieces.
| Material | Base estimate | Selected allowance | With allowance |
|---|---|---|---|
| Bricks | 1,350 pieces | 5% | 1,417.5 pieces → 1,418 whole bricks |
| Cement | 5.2 bags | 5% | 5.46 bags → 6 whole bags |
| Sand | 26 CFT | 25% | 32.5 CFT |
The allowances are separate tool defaults, not recommendations for every site. Round purchasing units after applying the relevant allowance. Keep unrounded quantities when comparing the method or costing partial units.
Why the three tools can give different mortar quantities
The 4.5-inch tool starts with a 30% mortar fraction, dry factor 1.42 and 1:4 ratio. The foundation tool starts with 25%, 1.3 and 1:6 respectively. All currently start with 13.5 bricks/CFT. Consequently, equal input volumes can give the same brick count but different cement and sand estimates. Check settings rather than assuming the wall label alone determines the result.
Foundation brickwork: measure each step
For a stepped foundation, calculate length × width × height for each masonry section and add the volumes. Exclude excavation, plain concrete and reinforced concrete from the brickwork quantity. Use your approved drawings for step dimensions, depths and bearing requirements; the calculator does not design foundations.
A practical checklist before ordering
- Measure from current drawings and confirm the actual masonry dimensions.
- Deduct relevant openings and check intersections once.
- Confirm brick dimensions and the applicable quantity factor.
- Review the mortar fraction, dry factor, mix and bag assumptions.
- Choose material-specific allowances based on handling and site conditions.
- Compare the output with a manual takeoff and supplier packaging.
Frequently asked questions
How many bricks are needed per cubic foot?
This tool defaults to 13.5, but that is an editable estimating coefficient. Actual requirements depend on brick dimensions, joints and masonry arrangement. Do not apply it universally to every country or product.
Can I enter wall area directly?
These three tools require volume. First multiply the measured face area by masonry thickness in matching units. Plaster area is a separate measurement.
Is a 4.5-inch wall always non-load-bearing?
The calculator does not establish a wall’s structural role. Follow the engineer’s design and local requirements; thickness alone is not sufficient to decide suitability.
Does this include labour, lintels or plaster?
The brickwork results cover the listed masonry materials. Labour, lintels, reinforcement and plaster require separate quantities and prices.
Start with the 9-inch brickwork calculator, choose the 4.5-inch wall tool for that measured scope, or use the foundation materials calculator. For surface finishing, continue to the plaster cement and sand calculator.
Method: Calculate Simply’s owner-supplied material workbook and the editable tool settings. For broader fired-clay brick guidance, see the Brick Industry Association technical notes, including topics on estimating and mortar. These resources do not validate the workbook’s coefficients for your project.