Mortar Bags Calculator
Calculate how many bags of mortar mix you need for bricklaying or blockwork from wall area and joint size, free in your browser.
Enter Values
Minimum 0
Minimum 1
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the number of bricks or blocks.
- Adjust bricks-per-bag if your mix differs from ~30.
How it works
Bags = bricks ÷ bricks laid per bag, rounded up. A 20 kg bag lays roughly 30 standard bricks.
Worked example
1000 bricks. ≈ 34 bags at 30 bricks per bag.
Common mistakes
- Joint thickness and brick size change the yield a lot — adjust bricks-per-bag.
- Not allowing ~10% spare for waste and spillage.
Frequently asked questions
How much mortar do I need for a wall?
Roughly 0.5–0.7 bags of mortar per square metre of single-brick wall, depending on brick size and joint thickness. The tool estimates from your wall area.
How many bricks does a bag of mortar lay?
As a rough guide, one 20 kg bag of pre-mixed mortar lays around 30–40 standard bricks, varying with joint size, brick type and mix.
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Cite this tool
Zerdly. (2026). Mortar Bags Calculator. Retrieved from https://www.zerdly.com/tools/mortar-bags-calculator/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.