How many cement blocks per square metre?

For the standard 440 by 215 millimetre block with a 10 millimetre joint, 9.88 per square metre — commonly rounded to 10 for estimating. The figure comes from the module: block plus joint gives 450 by 225 mm, and one divided by that area is 9.877. Larger formats cover more, so a 390 by 190 block gives 12.5 per square metre while a 600 by 250 gives only 6.3.

How many blocks per square foot?

For a US 8 by 8 by 16 inch CMU with a 3/8 inch joint, exactly 1.125 per square foot, which is 112.5 per hundred square feet. That figure is clean by design: the block actually measures 15 and five eighths by 7 and five eighths inches, so adding the joint brings it to precisely 16 by 8. The metric 440 by 215 works out to 0.918 per square foot by comparison.

Why is it 9.88 and not 10?

Because blocks do not divide evenly into a square metre. A 450 by 225 module tiles a square metre 2.22 times across and 4.44 times up, which multiplies to 9.877 — and a real wall is cut to fit rather than stopping at whole blocks. Rounding 9.877 up to 10 is fine for a quick estimate and adds about one percent, but the rounding should happen once at the end of the calculation rather than being baked into the rate and then multiplied.

How much does the mortar joint change the coverage?

More than most people expect. On a 440 by 215 block, a 10 millimetre joint gives 9.88 per square metre, 12 millimetres gives 9.75, 15 gives 9.56 and 20 gives 9.25. That is a spread of six percent across joint thicknesses a bricklayer might genuinely use. Working with no joint at all — measuring the bare block — gives 10.57, seven percent above the standard figure and the single most common source of an over-order.

What is the difference between a bed joint and a perpend?

The bed is horizontal, under each block; the perpend is vertical, between blocks in a course. In metric blockwork both are normally 10 millimetres and the distinction rarely matters. It matters on some US brick sizes, where three courses must land on an exact eight inches, forcing a bed joint wider than the perpend. This calculator keeps them separate so those sizes reproduce their published coverage exactly rather than approximately.

How many blocks do I need for a 100 square metre wall?

At 9.88 per square metre, 988 blocks before any wastage, or about 1,040 with the usual five percent allowance. Deduct openings from the area first — a hundred square metres of gross wall with two doors and four windows might be eighty-five net, which is a hundred and fifty blocks fewer. That is why a take-off starts with net area rather than gross, and why a coverage figure is a rate rather than an answer.

How much area will a pallet of blocks cover?

Divide the pallet count by the coverage. A pallet of 72 standard 440 by 215 blocks covers 72 ÷ 9.88 = 7.3 square metres. Pallet counts vary a great deal by supplier and block density, from around 48 for heavy dense blocks up to 90 or more for lightweight aerated ones, so take the count from the delivery note. This calculator will do that sum for you — type the pallet count into the blocks box and read the area.

Do bigger blocks save money?

They save labour rather than material. A 600 by 250 block covers 0.159 square metres against 0.101 for a 440 by 215, so you lay about 6.3 per square metre instead of 9.9 — roughly a third fewer units and a third fewer joints to fill and strike. The blocks themselves usually cost more per square metre of coverage, so the saving is in time on site. The trade-off is weight and handling: a large-format block is heavier and harder to place accurately single-handed.

Does this figure include wastage?

No, and it should not. Coverage is a geometric rate — how much wall one block occupies — and it is the same whether you break blocks or not. Wastage is an allowance applied to the order afterwards, typically five percent for straightforward walls and ten where there are many openings and corners producing unusable offcuts. Keeping the two separate means you can see what the wall genuinely needs and what you are adding as insurance.

Cement Blocks Per Square Metre

The short answer is 9.88 for a standard 440 by 215 millimetre block laid with a 10 millimetre joint, and 1.125 per square foot for a US 8 by 8 by 16 inch CMU. Those two figures cover most of the world's blockwork, and if that is all you came for, you have it. The longer answer is that the number is...

THE BLOCK

BLOCK SIZE

BED JOINT (mm)

PERPEND (mm)

Module 450 mm × 225 mm = 0.10125 m² of wall per block.

WORKS BOTH WAYS — TYPE IN EITHER

WALL AREA (m²)

BLOCKS

Area is driving — the block count follows.

BLOCKS PER SQUARE METRE

9.88

0.9176 per ft² · 91.8 per 100 ft² · 0.10125 m² each

FOR

10.00 m²

BLOCKS

+5% WASTE

104

Blocks per m²

9.877

Blocks per ft²

0.9176

Blocks per 100 ft²

91.8

Area per block

0.10125 m²

Module

450 mm × 225 mm

Bare block would give

10.57 / m²

That error

+7.0%

For your area

104 blocks

This page gives the rate, not the order. For a real wall with openings, courses and mortar, the block calculator does the whole take-off — it uses exactly the same coverage figure, so the two agree.

THE COVERAGE

Coverage is never a whole number. A 440 mm × 215 mm block on a 450 mm × 225 mm module gives 9.877 per m², not 10 — the blocks do not divide evenly into a square metre and a real wall is cut to fit. Rounding the rate before multiplying is where small orders drift; multiply first, round once at the end.

The joint is not a detail. Going from 10 mm to 20 mm changes the rate by 6.3%, which on a thousand-block order is dozens of blocks either way.

Live calculation · updates as you type

Created with❤️byeaglecalculator.com

HOW TO USE

1
Pick your block size. Selecting one brings its correct bed and perpend joints with it, which matters for US sizes where the module is designed around a 3/8 inch joint.
2
Adjust the joint if yours differs. The coverage figure and the chart both update as you type, so you can see immediately how much the joint is worth.
3
Type into either the area box or the blocks box — whichever you know. The other follows. Area drives when you are ordering; blocks drive when you want to know what a delivery will build.
4
Compare against the other sizes in the chart below if you are choosing between blocks. Larger formats cover more per unit, which is most of why they go up faster.

THE FORMULAS

Module(block L + perpend) × (block H + bed)

Blocks per m²1 / module area

Blocks per ft²per m² × 0.0929

Area per blockmodule area

Blocks for an areaarea × per m² × (1 + waste)

Area from blocksblocks / per m²

Bare-block errormodule area / block area − 1

US modulealways lands on a round inch

COVERAGE BY BLOCK SIZE

Block	Module	Per m²	Per 100 ft²	m² each
440 × 215 × 100 mm	450 × 225 mm	9.877	91.8	0.10125
440 × 215 × 140 mm	450 × 225 mm	9.877	91.8	0.10125
440 × 215 × 215 mm	450 × 225 mm	9.877	91.8	0.10125
390 × 190 × 190 mm	400 × 200 mm	12.500	116.1	0.08000
400 × 200 × 200 mm	410 × 210 mm	11.614	107.9	0.08610
500 × 200 × 200 mm	510 × 210 mm	9.337	86.7	0.10710
600 × 200 × 100 mm	610 × 210 mm	7.806	72.5	0.12810
600 × 250 × 100 mm	610 × 260 mm	6.305	58.6	0.15860
US CMU 8 × 8 × 16 in	16 × 8 in	12.109	112.5	0.08258
US CMU 4 × 8 × 16 in	16 × 8 in	12.109	112.5	0.08258

Metric figures assume a 10 mm joint, US a 3/8 inch one. Two rows are worth noticing. A 390 × 190 block with a 10 mm joint modules to exactly 400 × 200, giving precisely 12.5 per square metre. And the US CMU modules to exactly 16 × 8 inches, giving exactly 1.125 per square foot — both are designed that way rather than coming out round by chance.

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Last updated: July 29, 2026 · Formula verified · Eagle-eyed accuracy for every calculation.