Ordering the wrong number of bricks is one of the most common and expensive mistakes on a build. Too few, and work stops while you wait for a matching batch. Too many, and you have paid for pallets that sit in the yard. This guide gives you a reliable method to estimate bricks and mortar for any straight wall, plus the waste factor that keeps you from running short.

The one formula that matters

Everything starts from a single idea: divide the wall area by the area that one brick covers on the face, including its mortar joint. A brick never sits alone; each one carries a share of the joint around it. If you forget the joint, you will over-order.

So the working formula is: bricks = wall area / (brick face length + joint) x (brick face height + joint). A 10 mm joint is the common default for clay brickwork.

Step by step

1. Measure the wall length and height in metres, then multiply for the gross area.

2. Subtract openings. Doors and windows are not brick, so remove their area or you will pay for bricks you never lay.

3. Decide the wall thickness. A single-leaf (half-brick) wall uses one layer; a one-brick wall is double.

4. Divide the net area by the face area of one brick plus joint to get bricks per layer, then multiply by the number of leaves.

A useful rule of thumb

For a standard metric brick (roughly 215 x 102 x 65 mm) with a 10 mm joint, the widely used figures are:

Wall type	Approx. bricks per m2
Half-brick (single leaf)	60
One-brick (double leaf)	120

These numbers depend entirely on brick size. Vietnamese two-hole and solid bricks come in different dimensions, so measure your actual brick and recalculate rather than borrowing a figure blindly.

Do not forget mortar

Mortar volume rises with joint thickness and wall size. As a practical estimate, plan for roughly 0.02 to 0.03 cubic metres of mortar per square metre of half-brick wall, more for thicker walls and wider joints. Order sand and cement to match your mix ratio, and remember mortar cannot be stored once mixed.

The waste factor and why it exists

Bricks break in transit, get cut to fit corners, and some arrive chipped. Add a waste allowance of 5 to 10 percent. Use the higher end for detailed work with many cuts, arches, or curved walls, and the lower end for long, simple runs.

A real example

Say you build a boundary wall 10 m long and 1.8 m high as a single leaf, with no openings. Gross area is 18 m2. Using 60 bricks per m2 gives 1,080 bricks. Add 8 percent waste for the cuts at each end and pier, and you order about 1,166. Round up to a full pallet quantity so the batch and colour match.

Common mistakes and how to fix them

Ignoring the mortar joint. Counting bare brick size inflates the total. Fix: always add the joint to both dimensions before dividing.

Forgetting openings. Leaving doors and windows in the area over-orders. Fix: subtract every opening larger than a brick or two.

No waste allowance. Ordering the exact count guarantees a shortfall. Fix: add 5 to 10 percent every time.

Mixing batches later. Topping up from a new delivery can bring a visible colour shift. Fix: order the full quantity, including waste, in one go.

Action checklist

• Measure your actual brick, do not assume a standard size.
• Calculate gross wall area, then subtract openings.
• Add a 10 mm joint to length and height before dividing.
• Multiply by the number of leaves for wall thickness.
• Add 5 to 10 percent waste.
• Order mortar materials to match your mix ratio.
• Buy the whole lot in one batch for colour consistency.

Conclusion

Accurate estimating is just area divided by brick-plus-joint, minus openings, plus waste. Do this before you request a quote, and take your brick sample to the supplier so the size in your calculation matches the size you buy. That one habit prevents most ordering errors.

FAQ

How much waste should I really add?

Five percent for long, simple walls; up to ten percent for work with many cuts, corners, or curves. When in doubt, err slightly high, since a small surplus is cheaper than a work stoppage.

Does joint thickness change the count much?

Yes. Moving from a 10 mm to a 12 mm joint reduces the brick count per square metre and raises mortar volume. Decide your joint before you estimate.

Should I include bricks for piers and corners?

Corners and piers use extra bricks and produce more cut offcuts. They are the main reason your waste factor exists, so account for them in the higher end of the range.

How do I estimate mortar quantity?

Estimate mortar by wall volume and joint size, then convert to sand and cement using your mix ratio. Mix in small batches, because mortar has a short working life once water is added.

References

Brick manufacturers’ technical guides and bricklaying trade references commonly cite the 60-bricks-per-square-metre figure for standard metric format. Always confirm against your supplier’s actual product dimensions.