About

Miscounting bricks on a masonry project triggers costly re-orders, delivery delays, and idle labor. The number of bricks per square metre depends on the brick format (l × w × h) and the mortar joint thickness t_j, typically 10 mm. This calculator uses actual joint geometry to derive mortar volume rather than relying on rule-of-thumb ratios. It deducts openings, applies a configurable wastage factor (industry standard 5 - 10 %), and breaks mortar volume into cement and sand quantities based on your chosen mix ratio. Results assume single-wythe walls; for double-wythe or cavity walls, calculate each leaf separately.

Mortar density is taken as 2080 kg/m³ (wet, Type N/S average). Dry mix volume is inflated by a factor of 1.33 to compensate for void loss during mixing. Cement is assumed at 1440 kg/m³ bulk density. Pro tip: always round cement bags upward - partial bags absorb moisture and set prematurely in storage.

Formulas

The number of bricks per square metre of wall face is derived from the coursing module. Each course has height equal to brick height plus one bed joint. Each brick occupies a length equal to its face length plus one perpend (head) joint.

N_bricks/m² = 1(l + t_j) × (h + t_j)

where l and h are in metres. Net wall area subtracts openings:

A_net = (L_wall × H_wall) − n∑i=1 (w_i × h_i)

Total bricks with wastage:

N_total = A_net × N_bricks/m² × (1 + W100)

Mortar volume per square metre equals the gross wall volume (per m²) minus the brick volume (per m²):

V_mortar/m² = (1 × 1 × w_brick) − N_bricks/m² × l × w × h

Cement bags from mortar volume, using dry volume factor 1.33 and mix ratio R (cement : sand):

V_cement = V_mortar × 1.331 + R_sand

Variable legend: l = brick length, w = brick width (depth), h = brick height, t_j = mortar joint thickness, W = wastage percentage, R_sand = sand parts in mix ratio, L_wall = wall length, H_wall = wall height.

Reference Data

Brick Type	Length mm	Width mm	Height mm	Unit Weight kg	Bricks/m² (10 mm joint)
Standard (US)	203	92	57	2.0	70
Modular	194	92	57	1.8	73
King Size	295	92	70	2.9	41
Queen	295	70	70	2.6	41
Engineer	203	92	70	2.5	58
Roman	295	92	41	1.8	54
Utility	295	92	92	3.4	33
Metric Standard (UK)	215	102.5	65	2.3	60
Indian Standard	228	107	69	3.0	52
Australian Standard	230	110	76	2.7	46
Euro NF	240	115	71	2.5	49
NF Thin	240	115	52	2.0	64
Jumbo	203	92	92	3.1	48
Closure	203	92	92	3.0	48
Norman	295	92	57	2.5	44

Frequently Asked Questions

Increasing the mortar joint from 10 mm to 12 mm on a standard US brick (203 × 57 mm face) reduces the count from approximately 70 to roughly 63 bricks per square metre - a 10% decrease. This happens because each brick's coursing module (brick dimension + joint) grows in both directions, so the effect compounds. Always measure actual joint thickness from site samples rather than assuming 10 mm.

Wet (placed) mortar compacts to fill voids between sand grains. When you measure dry ingredients before mixing, you need roughly 33% more volume to achieve the same wet volume after hydration and compaction. This factor (1.33) is a widely accepted civil engineering approximation per IS 2250 and ACI 530.

For machine-made bricks on a well-managed site, 5% covers normal cutting and breakage. Hand-molded or reclaimed bricks with irregular dimensions warrant 8-10%. Curved walls, arches, or complex bond patterns (Flemish, English) can push wastage to 12-15% due to required cutting. The calculator allows 0-20% for flexibility.

Calculate each leaf (wythe) separately. For a standard cavity wall, run the calculator once for the outer leaf and once for the inner leaf, then sum the results. The mortar calculation already accounts for single-wythe depth (brick width). Cavity fill (insulation or grout) requires a separate volume calculation.

This calculator models stretcher bond (running bond), the most common pattern. Header courses in English or Flemish bond expose the short face (92 mm vs 203 mm for US standard), changing the perpend joint count per square metre. For English bond, mortar volume increases roughly 10-15%. Adjust by using a higher wastage factor or calculating header courses separately.

The calculator automatically converts cement volume to bags assuming standard 50 kg bags at a bulk density of 1440 kg/m³. One 50 kg bag occupies approximately 0.0347 m³. If your region uses 25 kg or 42.5 kg bags, divide the total cement weight shown by your bag weight.