Brick calculator — how many bricks do you need for a wall?
Calculate how many bricks you need to build a wall. Enter wall width, height and waste allowance — get the brick count, wall area in m² and volume in m³.
Current for 2026Methodology →
Wall Blocks Calculator — How Many Blocks for a Wall
The wall blocks calculator helps you estimate how many hollow blocks you need to build a wall. Enter the wall area, choose the block size and its price — the calculator returns the number of blocks (with a 5% margin), the number of mortar or adhesive bags and the material cost. Useful for planning your build and purchases.
Na tej stronie
How the calculator estimates the number of blocks
Blocks per m² = 1 / ((width/100) × (height/100)) 25×20 → 1/(0.25×0.20) = 20 pcs/m² 24×24 → about 17.4 pcs/m² 38×24 → about 11 pcs/m² Number of blocks = round up(area × blocks per m² × 1.05) Adhesive = area × 8 kg/m² 25 kg bags = round up(adhesive / 25) Cost = number of blocks × block price
Example: 30 m², 25×20 cm block, 6 zł/pc
A 30 m² wall, 25×20 cm block: per m² you need 1 / (0.25 × 0.20) = 20 pcs, so 30 × 20 × 1.05 = 630 blocks. Mortar: 30 × 8 = 240 kg → 10 bags of 25 kg. Cost: 630 × 6 zł = 3780 zł.
Frequently asked questions
How many blocks do I need per m² of wall?
It depends on the block face size. For 25×20 cm it is 1 / (0.25 × 0.20) = 20 pcs/m², for 24×24 cm about 17.4 pcs/m², and for 38×24 cm about 11 pcs/m². The calculator adds a 5% margin for cuts and waste.
Why does the calculator add a 5% margin?
Some blocks must be cut at corners and openings, and damage in transport happens. The standard margin is 5%; for complex shapes or many openings consider 7–10%.
How much mortar or adhesive do blocks need?
The calculator assumes about 8 kg of adhesive per m² of wall for thin-bed laying of ground blocks. Traditional cement-lime mortar uses more. The result is given in 25 kg bags.
How do blocks differ from bricks?
Blocks have hollows that reduce weight and improve thermal and acoustic insulation. Solid brick is heavier and more load-bearing. Ceramic and silicate blocks are used for load-bearing and partition walls.
What are thermal blocks (Porotherm, Ytong)?
They are elements with enhanced insulation. Porotherm is a ceramic block, often filled with wool. Ytong is aerated concrete — light and easy to work. Both allow single-layer walls.
Which block size for a load-bearing wall?
Single-layer walls use thick blocks (e.g. 38 cm wall width). Two-layer insulated walls need 24–25 cm. Partition walls use thinner elements.
Do I need to account for lintels over openings?
Yes. Lintels are fitted over windows and doors to carry loads. They are not blocks and the calculator does not count them — plan them separately from the design.
How do I measure the wall area for laying?
Area = length × height minus large window and door openings. Enter the net wall area and the 5% margin is added automatically. Some masons treat small openings as extra reserve.
Do block prices vary a lot?
Yes. Price depends on material, size, strength class and maker. A simple block costs a few zł, a large ceramic block with filling over a dozen zł each. Enter your current supplier price.
Does this calculator replace a construction design?
No. It gives an indicative estimate of blocks, mortar and cost. It does not account for lintels, ring beams, reinforcement or masonry craft. Final quantities should follow the design and a site manager.
Results are indicative and intended for preliminary purchase planning. They do not replace a construction design or consultation with a site manager. Actual material use depends on the structure, openings, lintels and masonry technique.
Related calculators
Plaster calculator — how many bags of plaster do you need?
Calculate how much plaster you need to render walls. Enter the area, layer thickness and waste allowance — get kilograms, cubic metres and number of 25 kg bags.