Calculate your result
Quick answer
Choose a method that matches your materials. For site-mixed brick mortar, calculate wet volume from net wall area and an agreed rate, then split dry materials by the specified cement:sand ratio. Premix needs the bag’s wet yield. Thin brick fixing and pointing products need their own coverage rates and separate calculations.
How it works
Use this brick mortar calculator for South Africa to estimate cement and sand for site-mixed masonry mortar, premix mortar bags or a thin brick product with confirmed coverage. Enter net wall area and the figures for your actual materials. Maxi bricks need a suitable mortar rate, not an automatic discount.
Formula
Site mix: wet m³ = net m² × leaves × wet rate × (1 + allowance/100). Premix bags = wet m³ × 1000 ÷ litres per bag, rounded up. Product bags = net m² × kg/m² × (1 + allowance/100) ÷ kg per bag, rounded up.
Assumptions and common mistakes
Check units, input values and the method before relying on an estimate. Review the existing tool notes and official sources below.
Formula
Site mix: wet m³ = net m² × leaves × wet rate × (1 + allowance/100). Premix bags = wet m³ × 1000 ÷ litres per bag, rounded up. Product bags = net m² × kg/m² × (1 + allowance/100) ÷ kg per bag, rounded up.
| Method | Required input | Purchase result |
|---|---|---|
| Site mix | Wet m³/m², mix and conversion assumptions | Cement bags and dry sand |
| Premix mortar | Wet litres per complete mortar bag | Full premix bags |
| Thin brick product | Product kg/m² and kg per bag | Full bags for one specified product |
How to use the brick mortar calculator
Measure net wall area after openings. For masonry, enter the number of similar leaves and a confirmed wet mortar rate for one leaf. A leaf is one thickness of masonry. Select site mix for separate cement and sand, premix for a complete bagged mortar, or product coverage for a specified thin brick adhesive or pointing material.
Site-mixed cement and sand formula
Multiply net area by leaves and the wet mortar rate, then add one allowance. Multiply wet volume by the agreed dry-material volume factor. Split the dry volume using the cement:sand parts by volume. Convert cement bulk volume to mass using the entered bulk density, divide by cement bag mass and round up. The dry sand estimate is a bulk volume, not an automatic delivered tonnage.
Worked example: cement and sand
At the example inputs of 40 m², one leaf, 0.02 m³ wet mortar/m² and 10% allowance, wet volume is 0.88 m³. A dry factor of 1.33 gives 1.1704 m³ of dry materials. With a hypothetical 1:6 cement:sand ratio and bulk cement density of 1,440 kg/m³, cement is 240.768 kg, so five 50 kg cement bags are needed. Dry sand is about 1.0032 m³. These inputs illustrate arithmetic, not a specified mortar class.
Maxi brick mortar calculator inputs
Use a mortar rate confirmed for the actual maxi brick size, joint thickness, bedding method and wall arrangement. Larger units do not justify one universal reduction factor. Perforations, frogs, hollow sections and site losses affect consumption. The calculator applies your entered rate directly and never changes it merely because a brick is called maxi.
Thin brick mortar calculator: fixing and pointing
Thin brick or brick slips can use a specified fixing bed or adhesive and a separate pointing product. Use the coverage method only with the manufacturer’s kg/m² for the actual application and bag mass. Calculate fixing and pointing separately; their rates and bag sizes may differ. This mode does not choose an adhesive or turn ordinary bricklaying mortar into a suitable fixing product.
Premix mortar bags and product coverage
Premix mortar already contains its specified dry ingredients. Enter the labelled litres of usable wet mortar produced by one bag. Do not treat total premix bag mass as cement mass or add extra sand automatically. In product-coverage mode, enter kilograms per square metre for one finished surface. That rate is not multiplied by masonry leaves. Set allowance to zero if losses are already included in the supplied rate.
What the assumptions do not decide
The example wet rate, mix, dry factor, cement density and allowance are editable assumptions. Confirm required strength, cement type, material compatibility, exposure and workmanship separately. The result excludes plaster, concrete, filled block cores, structural design, water quantity and products not entered. Sand moisture and bulking can alter ordering quantities; ask your supplier about delivery units.
Last reviewed: 15 October 2026. Reviewed by the 99tools team. Editorial and corrections policy.
Quantity estimates only. Product suitability, wall stability and any structural design must be confirmed for the job.
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- Maxi Bricks vs Stock Bricks: Quantity and Size
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- Brickforce Prices: Compare Roll Quotes in South Africa
- Sand and Cement Mix Ratios: Mortar, Plaster and Screed
- How Much Sand and Cement per m² or 1,000 Bricks?
- Maxi Brick Prices and Pallets: How to Compare Quotes
- How to Measure Wall Plaster Area in m²
- Cement, Gypsum, Lime and Pool Plaster Quantities
Frequently asked questions
How do I calculate brick mortar?
Multiply net masonry area by the number of similar leaves and the confirmed wet mortar rate for one leaf. Add one allowance, then use the specified mix for separate cement and sand or the bag yield for premix.
Can I use this as a maxi brick mortar calculator?
Yes. Enter the mortar rate confirmed for your actual maxi brick and joint arrangement. There is no universal maxi-brick discount or automatic rate change.
How do I calculate thin brick mortar or adhesive bags?
Use product coverage with the manufacturer’s kg/m² and bag mass. Calculate the fixing product and pointing product separately using their own coverage figures.
Is premix bag mass the same as cement mass?
No. A premix mortar bag contains its formulated ingredients. Use its stated wet yield, rather than treating the entire bag as cement.
Is a 1:6 mortar mix always correct?
No. It is an editable example for quantity arithmetic. The required mortar specification must be confirmed for the materials, exposure and job.
Does this calculate the amount of water?
No. Follow the selected product or specified mixing instructions. Water cannot be inferred reliably from the purchasing estimate alone.
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Helpful guides
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