Mortar calculator

Enter how many blocks or bricks you're laying, or the wall area, to see how many bags of mortar mix to buy.

By the Calcist team · Checked against known answers · Updated October 27, 2026

Private: calculated on your device. Nothing you type is sent anywhere.

Next: Counting the blocks first? Use the concrete block calculator.

How much mortar do I need?

QUIKRETE says an 80 lb bag of its Mortar Mix lays about 13 standard 8 × 8 × 16 blocks, or up to 37 standard bricks.

Bags = units ÷ units per bag × (1 + extra %), rounded up
Blocks: 13 per bag · Bricks: 37 per bag
From wall area: 1.125 blocks or 6.75 modular bricks per sq ft

Worked examples

100 blocks: 100 ÷ 13 = 7.7, so 8 bags with no extra.
500 bricks with 10% extra: 500 ÷ 37 × 1.1 = 14.9, so 15 bags.
A 100 sq ft brick wall is 675 modular bricks (BIA), which takes about 5.5 cu ft of mortar, or 21 bags with 10% extra.

Mixing your own

Premixed mortar mix only needs water. Masons mixing in bulk usually buy masonry cement and sand instead; a common estimate is about 3 bags of masonry cement per 100 blocks. The Brick Industry Association suggests allowing 15 to 25% extra for mortar waste on site.

Limitations

Joint thickness, block shape and how much is dropped all change the amount. Treat the result as a starting estimate and buy a bag or two extra.

Sources

How we checked this

Before every update, this calculator is run in a real browser with these known answers, and it must match all of them:

100 blocks, no extra: 8 bags ✓
500 bricks with 10%: 15 bags ✓
100 sq ft of brick: 675 bricks, 21 bags with 10% ✓
Edge: 13 blocks is exactly 1 bag ✓

Last checked October 26, 2026. Spotted something wrong? The math is done in your browser with the formula shown on this page, so you can check any result by hand.

Add this calculator to your website (free)

Paste this code into any web page. The calculator works on your page, resizes itself, has no ads and no tracking, and nothing your visitors type is sent anywhere. More about embedding.

<iframe src="https://calcist.com/embed/mortar-calculator/" title="Mortar calculator" width="100%" height="640" loading="lazy" style="border:0;max-width:760px"></iframe>
<p style="font:14px/1.4 sans-serif;margin:4px 0 0"><a href="https://calcist.com/mortar-calculator/">Mortar calculator</a> by Calcist</p>
<script src="https://calcist.com/embed.js" async></script>

Questions people ask

How many blocks does a bag of mortar lay?

About 13 standard 8 × 8 × 16 blocks per 80 lb bag of premixed mortar mix.

How many bricks per bag of mortar?

Up to 37 standard bricks per 80 lb bag of QUIKRETE Mortar Mix.

How much mortar for 100 blocks?

About 8 bags of 80 lb mortar mix, or about 3 bags of masonry cement plus sand.

How many bricks are in a square foot?

6.75 modular bricks per square foot with 3/8 inch joints (BIA Technical Note 10).

Related calculators

Concrete block calculatorCMU or cinder blocks for a wall, with mortar and core grout.Retaining wall calculatorWall blocks, caps and gravel for a block wall.Concrete bag calculator80, 60 or 40 lb bags and pallets for a slab or post holes.Square footage calculatorAdd up rooms and odd shapes in feet and inches, subtract cutouts, and price the floor.