Block mortar calculator

Estimate mortar in a uniform masonry grid from wall area, unit size, wall thickness and joint thickness.

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Wall face area

Masonry unit length

More inputs and assumptions

Masonry unit height

Wall thickness

Joint thickness

Extra allowance (%)

Answer

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Estimate mortar in a uniform masonry grid from wall area, unit size, wall thickness and joint thickness.

More results

Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

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Formula and assumptions

Mortar volume = wall area × thickness × (1 − unit face area/module area). Assumes full bed and head joints through the stated thickness. Hollow-block face-shell bedding, openings, mortar yield and structural specifications are not modeled.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-26

Using Block mortar calculator

Estimate mortar in a uniform masonry grid from wall area, unit size, wall thickness and joint thickness.

Next: Brick calculator

A worked example

Example inputs: wall face area = 20, masonry unit length = 0.4, masonry unit height = 0.2, wall thickness = 0.1, joint thickness = 0.01, extra allowance (%) = 10. Mortar volume before allowance = 0.141695702671.

Before you use the result

Example results for wall face area

These examples use Masonry unit length: 0.4; Masonry unit height: 0.2; Wall thickness: 0.1; Joint thickness: 0.01; Extra allowance (%): 10. They are reference calculations, not recommended settings.

Wall face area	Mortar volume before allowance
10	0.0708478513357
20	0.141695702671
40	0.283391405343

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