What this calculator works out
Ordering bricks for a wall comes down to one number most people want fast: how many to buy. But a wall isn't just bricks; it's bricks bedded in mortar, and mortar is sand and cement in a ratio, converted into tonnes and bags before anyone can put in an order. This calculator takes the wall's size, the brick size, whether it's a half-brick or one-brick wall, and a wastage allowance, and turns all of that into a full shopping list in one pass: bricks to buy, mortar volume, sand in tonnes and cement in 25kg bags, with an optional cost if you know your local brick price.
It works for a UK garden wall in 215 × 102.5 × 65mm bricks, a US wall in modular brick, or anything in between: every measurement has its own metric or imperial toggle, and a custom brick size is there for anything neither standard size covers.
How the bricks-per-m² maths works
Bricks don't sit edge to edge on a wall face; there's a mortar joint all the way round each one. That joint means every brick effectively "owns" a bit more wall than its own printed face size, the same coordinating-size idea this site's Paving and Tile calculators use for slabs and tiles. Add the joint width to the brick's length and its height, multiply those together, and that's the wall area one brick actually accounts for; one divided by that is the bricks needed per square metre.
For the UK standard brick, 215 × 65mm with a 10mm joint, that's a 225 × 75mm coordinating face, or 0.016875 m². One divided by 0.016875 is 59.26 bricks per m², which trade practice rounds up to the familiar 60 per m² used by brick manufacturers and merchants alike, the figure this calculator uses for a half-brick (single skin) UK wall. A one-brick (double skin) wall is taken at double that, 120 per m², the same doubling convention manufacturers' own calculators use; the exact bond pattern, English or Flemish, shifts this a little in practice, so treat 120 as a solid ordering estimate rather than an exact bond count.
US modular brick works the same way but is conventionally quoted per square foot rather than per square metre: 6.75 bricks per sq ft for a single wythe wall, 13.5 for a double wythe, figures published in the Brick Industry Association's brick size guidance and repeated across US masonry merchants' own coverage charts.
Doors and windows are subtracted from the gross wall area first, since no bricks or mortar are needed where an opening sits; whatever's left is the net area the rate above is applied to, then rounded up to a whole brick, since no merchant sells part of one.
A worked example
Take a UK garden wall 6m long and 2.4m high, 14.4 m² gross, with a 2 m² door and a 1.5 m² window taking 3.5 m² out of it, leaving 10.9 m² net. Built half-brick in UK standard bricks with 5% wastage: 10.9 × 60 = 654 bricks before waste; 654 × 1.05 = 686.7, rounded up to 687 bricks to buy. Mortar for that wall, at 0.025 m³ per m² of half-brick walling, is 10.9 × 0.025 = 0.2725 m³, plus the same 5% wastage, 0.286 m³. Split 1:4 by volume, that's 0.057 m³ of cement, 82.4kg, rounding up to 4 bags of 25kg cement, and 0.229 m³ of sand, which at 1.6 tonnes per m³ comes to 0.366 tonnes. At a rough £0.45 a brick, materials come to 687 × £0.45 = £309.15, before mortar, sand, cement and labour.
The American equivalent: a 200 sq ft wall (18.58 m²), no openings, half-brick (single wythe) in US modular brick with 10% wastage. 200 × 6.75 = 1,350 bricks before waste; 1,350 × 1.1 = 1,485 bricks to buy. Mortar is 18.58 × 0.025 = 0.465 m³, plus 10% wastage, 0.511 m³; split 1:4, that's 6 bags of cement and 0.654 tonnes of sand. At a rough $0.60 a brick, that's 1,485 × $0.60 = $891, again before mortar, sand, cement and labour.
Mortar, sand and cement
Rather than working mortar out brick by brick, this calculator uses the same "per m² of walling" convention published mortar calculators and general bricklaying guidance use: roughly 0.02 to 0.03 m³ of mortar per m² of half-brick walling is the commonly quoted range, and this tool uses the mid-point, 0.025 m³/m², doubled to 0.05 m³/m² for a one-brick wall, matching the same doubling used for the brick count. Some suppliers instead quote a rough "per brick" rule of thumb, commonly around 0.6 to 0.7 litres per brick laid; dividing our m²-based figure by 60 bricks per m² gives about 0.42 litres per brick, a little lower. That gap is mostly frog-filling (see below) and a general contingency already folded into the per-brick rule of thumb; this calculator keeps that separate, adding the same wastage percentage chosen for bricks to the mortar figure instead of double-counting it in the base rate.
Once the total mortar volume is known, it's split by the chosen ratio, 1 part cement to 4 or 5 parts sand by volume, both commonly used for general-purpose bricklaying mortar. Sand is converted to tonnes at 1.6 tonnes per cubic metre and cement to 25kg bags at a bulk density of 1,440 kg per cubic metre, the same figures this site's Paving Calculator uses, both traceable to the Concrete Society's published density for bagged cement.
Frogs, up or down
Most UK facing and common bricks are pressed with a frog, the shallow indentation in one bed face. Laid frog up, the mortar bed fills that indentation as the next course goes down, keying the brick in and using a little more mortar than a flat bed would; laid frog down, the indentation sits empty against the course below, using less mortar but giving a weaker mechanical key. General bricklaying guidance recommends frog up as the default for load-bearing and most general brickwork, with frog down reserved for specific situations such as the top course under a coping, or a soffit course where an empty frog underneath would otherwise be visible and collect water. This calculator's mortar figures assume ordinary frog-up laying.
Engineering bricks vs facing bricks
Engineering bricks are made dense, with low water absorption and high compressive strength, classed as Class A or Class B under BS EN 771-1. They're specified below the damp-proof course, in retaining walls, manholes, inspection chambers and other load-bearing or below-ground work where strength and water resistance matter more than looks. Facing bricks are chosen mainly for appearance, a wide range of colours, textures and finishes for the visible face of a wall above the damp-proof course. The size and coordinating-face maths on this page apply the same way to either type; what changes between them is strength, absorption and price, not the counting method.
Questions people ask
Where does the 60 bricks per m² figure come from?
A UK standard brick, 215 × 65mm on its face, with a 10mm mortar joint, has a coordinating face of 225 × 75mm, 0.016875 m². One divided by that is 59.26 bricks per m², which brick manufacturers and builders' merchants round up to 60 for a half-brick, single-skin wall in stretcher bond. This calculator uses that same rounded, trade-standard figure.
Should bricks be laid frog up or frog down?
Frog up is the general default: the mortar bed fills the indentation as the next course is laid, giving a stronger mechanical key, and using a little more mortar than a flat bed. Frog down is sometimes used on a top course under a coping, or where an empty frog underneath would be visible or collect water, but isn't the general recommendation for ordinary brickwork.
What's the difference between engineering and facing bricks?
Engineering bricks are dense, low-absorption and high-strength, classed as Class A or B under BS EN 771-1, used below the damp-proof course and in load-bearing or below-ground work. Facing bricks are chosen mainly for their appearance and are used above the damp-proof course. Both are counted the same way on this page; only strength, absorption and price differ.
How much sand and cement does a wall need?
This calculator works it out from the wall's net area and thickness, using a published mortar-per-m² range, then splits that mortar volume by the chosen 1:4 or 1:5 cement-to-sand ratio, converting sand to tonnes and cement to 25kg bags. A 10.9 m² half-brick wall, for example, needs about 4 bags of cement and 0.37 tonnes of sand at a 1:4 mix.
Half-brick or one-brick, what's the real difference?
A half-brick (single skin) wall is one brick's width thick, about 102.5mm, common for a garden wall, boundary wall or the outer leaf of a cavity wall. A one-brick (double skin) wall is two skins bonded together, roughly double the thickness, needed where a free-standing wall must stand taller or carry more load. It needs roughly double the bricks and double the mortar of a half-brick wall for the same area.
How much wastage should I allow when buying bricks?
5% suits a straightforward run with square corners and few cuts. 10% is the safer default once there's cutting round openings, piers, or a less regular layout, since cut bricks break more often than whole ones. The same percentage is applied to the mortar, sand and cement figures on this page too, to cover mixing losses and spillage.
This calculator uses standard UK and US brick sizes and published typical figures for bricks-per-m², mortar quantity and material bulk densities, checked against at least two independent sources named above (the Brick Development Association and Wienerberger's own guidance for the UK figures, the Brick Industry Association's Technical Note 10 and general US masonry coverage charts for the modular figures). Real coverage varies a little with bond pattern, joint consistency and how a wall is actually laid, so treat the figures here as a solid ordering estimate and confirm exact quantities with your supplier before a large order.