🧱 Mortar Calculator

Mortar coverage conventions

These are widely cited masonry trade rules of thumb for standard unit sizes and typical joint widths — actual consumption varies with joint thickness and unit dimensions.

• These figures assume standard unit dimensions and typical 3/8-inch mortar joints; thicker joints, larger units, or non-standard brick sizes will increase mortar consumption above these estimates.
• Site-mixed sand volume assumes a common 1:4 (cement:sand) mortar mix; adjust proportionally for a richer or leaner mix specification.

How much mortar does a brick or block wall need?

Mortar bonds masonry units together in the joints between them, and the quantity needed depends on unit size, joint thickness and how many units are being laid. The masonry trade uses published rule-of-thumb coverage figures — commonly about 7 bags of pre-blended mortar per 1,000 standard bricks at typical 3/8-inch joints, or about 1 bag per 28 concrete masonry (CMU) blocks — as a quick estimating shortcut.

These coverage figures assume standard unit sizes and typical joint thickness; larger units, thicker joints, or a different brick size will change actual mortar consumption, so the figures here are a planning estimate rather than a precise take-off for unusual unit sizes.

How to use this mortar calculator

1. Enter the total number of units (bricks or blocks) to be laid.
2. Select whether the units are standard bricks or concrete masonry (CMU) blocks.
3. Read the number of mortar bags needed, the exact (unrounded) bag count, and an estimated sand volume if site-mixing mortar instead of using pre-blended bags.

The formula behind the mortar estimate

For standard bricks, bag count equals (number of bricks ÷ 1,000) × 7, based on the published convention of about 7 bags of 80 lb (≈36 kg) mortar per 1,000 bricks at 3/8-inch joints. For CMU blocks, bag count equals number of blocks ÷ 28, based on the convention of about 1 bag per 28 blocks. Site-mixed sand volume estimates about 0.55 m³ of sand per 1,000 bricks (or a proportional amount for CMU) for a typical 1:4 mortar mix.

Worked example: laying 500 standard bricks needs (500 ÷ 1,000) × 7 = 3.5 bags, rounded up to 4 bags of pre-blended mortar, with about 0.275 m³ of sand if mixing on-site (500 ÷ 1,000 × 0.55).

Common mistakes

• Applying the standard-brick coverage rate to oversized or non-standard brick, which understates the mortar needed.
• Not adjusting for thicker-than-3/8-inch joints, which increases mortar consumption above the standard estimate.
• Confusing mortar (used between masonry courses) with grout (used to fill hollow CMU cores) — they serve different purposes.
• Ordering pre-blended bags without checking whether the project specifies a Type N, S or M mortar, which affects strength and suitability, not just quantity.

常见问题

参考文献

1. Brick Industry Association (BIA) — Technical Notes on Brick Construction: standard mortar coverage conventions.
2. National Concrete Masonry Association (NCMA) — TEK notes on mortar and CMU coverage estimating.
3. ASTM C270 — Standard Specification for Mortar for Unit Masonry: mortar type and mix reference.