- Wet mortar (+15%)
- 0.15 m³
- Cement
- 57 kg
- Cement bags
- 2 × 50 kg · 3 × 25 kg
- Sand
- 0.16 m³
Mortar from the joint geometry, frogs unfilled; dry volume = 1.33 × wet. Cement at 1440 kg/m³.
How the Brick & Block Calculator works
The number of bricks or blocks comes from the wall face area and the size of one unit plus its mortar joint: a unit laid with a joint j covers (l + j) × (h + j) of wall face. Deduct doors and windows from the area first. A one-brick (double wythe) wall has two leaves, so it takes twice the units.
Mortar is worked out from the joint geometry. Each unit owns one bed joint and one head joint, a strip l + h + j long and j thick, as deep as the unit is wide. Hollow concrete blocks are laid on face-shell bedding, so only their two face shells are mortared. A double wythe adds a full collar joint between the leaves. Frogs are taken as unfilled.
Cement and sand: the dry volume is about 1.33 times the wet mortar volume, split by the cement : sand ratio, with cement at 1440 kg/m³. In US units cement is given in cubic feet, where one bag of portland or masonry cement counts as one cubic foot, the convention behind ASTM C270 proportions.
- Units per wall area
- N = leaves / ((l + j)(h + j))
- Mortar per unit
- V = j × (l + h + j) × w (w = 2 × face shell for hollow blocks)
- Cement for 1 : n mortar
- C = 1.33 × V / (1 + n) × 1440 (kg)
Worked example: bricks and mortar for a 10 m² half-brick wall
Given
- Net wall area 10 m² (openings already deducted)
- India traditional brick 230 × 110 × 75 mm, 10 mm joints, one leaf
- Mortar 1 : 6; waste 5% on bricks, 15% on mortar
Steps
- Bricks per m²: 1 / (0.240 × 0.085) = 49.0, so 490.2 bricks; with 5% waste, 515.
- Mortar per brick: 0.010 × (0.230 + 0.075 + 0.010) × 0.110 = 0.000347 m³; × 490.2 = 0.170 m³; with 15% waste, 0.195 m³.
- Dry volume: 1.33 × 0.195 = 0.260 m³, split 1 : 6 over 7 parts.
- Cement: 0.260 / 7 = 0.0371 m³ × 1440 = 53 kg, or 2 bags of 50 kg. Sand: 0.260 × 6 / 7 = 0.223 m³.
Result: 515 bricks and 0.195 m³ of mortar: 53 kg of cement (2 × 50 kg bags) and 0.223 m³ of sand.
Enter the same values in the calculator above to check each step.
Frequently asked questions
How many bricks are in a square metre?
With 10 mm joints, one leaf: 59 UK bricks (215 × 65 mm face), 49 Indian traditional bricks (230 × 75 mm), 50 Indian modular bricks (190 × 90 mm) and 48 Australian bricks (230 × 76 mm). Double it for a one-brick (double wythe) wall.
How many bricks per square foot?
A US modular brick (7⅝ × 2¼ in face) with 3/8 in joints covers 8 × 2⅝ = 21 in², so 6.86 bricks per square foot of single-wythe wall, or 686 per 100 ft².
How many concrete blocks per square foot?
A standard 8 × 8 × 16 CMU (15⅝ × 7⅝ in face, 3/8 in joints) covers 16 × 8 = 128 in², so 1.125 blocks per square foot, or 112.5 per 100 ft². Metric 390 × 190 mm blocks with 10 mm joints come to 12.5 per m².
How much cement and sand for 1 m³ of mortar?
The dry volume is 1.33 m³. At 1 : 4 that is 0.266 m³ of cement (383 kg, 7.7 bags of 50 kg) and 1.064 m³ of sand; at 1 : 6, 0.19 m³ of cement (274 kg, 5.5 bags) and 1.14 m³ of sand.
How much waste should I allow?
About 5% for bricks and blocks, more on walls with many openings and corners. For mortar allow 10 to 25%: droppings, filled frogs and mortar that falls into hollow block cores are not in the joint volume.