Brick calculator — how many bricks do you need for a wall?
Calculate how many bricks you need to build a wall. Enter wall width, height and waste allowance — get the brick count, wall area in m² and volume in m³.
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Mortar Calculator — How Much Mortar for a Wall
The mortar calculator helps you estimate how much mortar you need to build a wall. Enter the wall area, choose its thickness and the price of a dry-mix bag — the calculator returns the mortar volume in m³, the number of 25 kg bags and an approximate cost. Useful for planning purchases and your build budget.
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How the calculator estimates mortar needs
Mortar consumption (m³ per m² of wall): 12 cm wall = 0.03 m³/m² 25 cm wall = 0.05 m³/m² 38 cm wall = 0.08 m³/m² Volume = area × consumption × 1.05 (5% reserve) 25 kg bags = round up(volume × 64) (1 m³ ≈ 1600 kg / 25 kg = 64 bags) Cost = number of bags × bag price
Example: 20 m² wall, 25 cm thick, bag €15
A 20 m² wall, 25 cm thick: consumption 0.05 m³/m² → 20 × 0.05 × 1.05 (reserve) = 1.05 m³ of mortar. That is about 68 bags of 25 kg (1.05 × 64, rounded up). At 15 per bag the cost is about 1020.
Frequently asked questions
How much mortar is needed per 1 m² of wall?
Consumption depends on wall thickness: about 0.03 m³/m² for a 12 cm wall, 0.05 m³/m² for a 25 cm wall and 0.08 m³/m² for a 38 cm wall. The calculator adds a 5% reserve for losses, so real needs are slightly higher.
What is the cement-to-sand ratio?
A typical cement bricklaying mortar is 1:3 to 1:4 (cement : sand). Stronger 1:3 suits load-bearing walls, while 1:4 suits partition walls. Adding lime (1:1:6) improves workability and the elasticity of the wall.
How many 25 kg bags of dry mortar do I need?
The calculator assumes 1 m³ of dry mix is about 1600 kg, i.e. 64 bags of 25 kg, and rounds the number up. For a 20 m² wall 25 cm thick the volume is 1.05 m³ → about 68 bags.
How long does bricklaying mortar take to dry?
Cement mortar initially sets in 1–2 hours, reaches load-bearing strength after 24–48 hours and full design strength after 28 days of curing. During this time protect the wall from rapid drying and rain.
Can you lay bricks in frost?
Bricklaying is not recommended below +5°C because water in the mortar can freeze and damage the structure. In low temperatures use anti-frost additives or pause the work, and protect the fresh wall from frost for several days.
Ready-mix bags or site-mixed mortar?
Bagged ready-mix gives consistent quality and only needs water added — it is convenient. Site-mixed mortar can be cheaper in large quantities but requires precise dosing and control of sand quality.
How much water to add to a 25 kg bag?
Usually about 3–4 litres per 25 kg bag — the exact amount is given by the manufacturer. Too much water reduces strength, too little worsens workability. Add water gradually until you get a uniform, plastic consistency.
Does wall thickness affect mortar use?
Yes, significantly. A thicker wall has more joints and a larger bonding area. A 38 cm wall uses about 2.5 times more mortar per m² than a 12 cm wall, which is why the calculator asks for wall thickness.
How thick should the joints be?
A standard bricklaying joint is 10–12 mm. Thinner joints reduce consumption but require even bricks. For aerated concrete, thin-layer mortars with 1–3 mm joints are used, which changes material consumption.
Does the calculator include waste?
Yes, it adds a 5% reserve for losses and waste. The result is still indicative — actual consumption depends on brick evenness, joint thickness and the bricklayer experience. It is worth buying a small reserve of material.
Results are indicative. Actual mortar consumption depends on joint thickness, brick evenness, the bricklayer experience and weather. Before buying, verify the mix manufacturer data and buy a small reserve of material.
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