Mortar Calculator

Work out how much mortar a brick or block wall needs. Enter the wall and unit size, pick a mix ratio, then get volume, cement bags, sand and water.

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Wall Dimensions

Wall Length

Wall Height

Wall Thickness

Brick / Block Details

Masonry Type

Brick Length

Brick Height

Brick Width / Depth

Mortar Joint Thickness

Mortar Mix & Waste

Mortar Mix Ratio (Cement:Sand)

Waste Factor

Water-Cement Ratio

Cost Details

Price per Cement Bag

Price per Unit Sand

Additional Cost

Mortar Summary

Mortar Volume: —

Wall Area—

Wall Volume—

Number of Bricks—

Mortar Volume (wet)—

Mortar Volume (dry)—

Cement Required—

Sand Required—

Water Required—

Cement Cost—

Sand Cost—

Estimated Total Cost—

Component	Value	Unit

Enter details and calculate to see breakdown.

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Creator & Reviewer

Faiq Ur Rahman is a web designer, digital product developer, and Founder of Techraxy, a growing platform of online calculators and utility tools. He specializes in building structured, user-friendly tools focused on finance, health, conversions, productivity, and everyday problem-solving. He is passionate about developing practical digital solutions that make complex tasks simpler for users worldwide.

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Mortar Calculator: Cement, Sand and Water for Brick and Block

Mortar is the part of a masonry wall nobody measures and everybody runs short on. This mortar calculator counts the units in a brick or block wall, works out the wet mortar the joints will hold, inflates it to dry volume, and splits the result by your chosen mix ratio. You’ll see cement in bags, sand in cubic yards and tons, and water in gallons and liters. Enter local prices for a running total before you head to the yard.

How to Use the Mortar Calculator

Pick your currency from the top dropdown.
Enter the wall length, height, and thickness, then set the unit for each.
Choose a masonry type: standard brick, King brick, or 4″, 6″, or 8″ concrete block.
Confirm the brick or block dimensions. The fields update to match the preset.
Set the mortar joint thickness. Three-eighths of an inch is the residential default.
Pick a mix ratio from 1:2 up to 1:6.
Adjust the waste factor. The default of 15 percent covers most jobs.
Add your water-cement ratio, then enter prices per bag and per unit of sand.

The Summary tab leads with dry mortar volume. Detailed Breakdown lists every value behind the result, from the brick count to the water figure.

How the Mortar Calculator Formula Works

Mortar volume comes from the gap between the wall and the units that fill it. The calculator measures the wall as a solid block, subtracts the total volume of brick or block inside it, and treats the difference as mortar.

Formula: Wall volume = Length × Height × Thickness
Formula: Unit count = [ Wall face area ÷ ((Unit length + Joint) × (Unit height + Joint)) ]
Formula: Mortar (wet) = Wall volume − (Unit count × Unit volume)
Formula: Mortar (dry) = Mortar wet × 1.33 × (1 + Waste %)
Formula: Cement bags = [ (Cement part ÷ Total parts) × Mortar dry ÷ 1 ft³ per 94 lb bag ]
Formula: Sand volume = (Sand part ÷ Total parts) × Mortar dry

The 1.33 factor handles two real-world effects. Sand bulks when it’s damp, and the dry ingredients don’t pack to the same volume as the finished mortar. Skipping it undershoots by about a quarter.

Mix ratio parts split the dry mortar. In a 1:4 mix, cement is 1/5 of the volume and sand is 4/5. Cement converts to bags at 94 lb per bag, which is the standard US sack and roughly 1 cubic foot of loose cement. Sand converts to weight at 100 lb/ft³.

The water-cement ratio defaults to 0.5. That means every pound of cement gets half a pound of water. Lower the ratio for stronger mortar, raise it for easier spreading.

Worked Example: A 20 ft × 8 ft Wall, 8 in Thick

Say you’re building a 20 ft long, 8 ft high wall, 8 inches thick, using standard brick with a 3/8″ joint. Mix ratio is 1:4. Waste factor is 15 percent. Water-cement ratio is 0.5.

Wall face area: 20 × 8 = 160.00 ft²
Brick face with joint: 8.375 × 2.625 in = 0.1526 ft²
Brick count: 160 ÷ 0.1526 = 1,048.2, rounded to 1,049 bricks
Wall volume: 20 × 8 × 8/12 = 106.67 ft³
Brick volume each: 8 × 2.25 × 3.625 in = 0.03776 ft³
Total brick volume: 1,049 × 0.03776 = 39.61 ft³
Mortar wet: 106.67 − 39.61 = 67.06 ft³
Mortar dry base: 67.06 × 1.33 = 89.19 ft³
Mortar dry with 15% waste: 89.19 × 1.15 = 102.57 ft³, or 3.80 yd³
Cement: 1/5 × 102.57 = 20.51 ft³, rounded to 21 bags
Sand: 4/5 × 102.57 = 82.06 ft³, or 3.04 yd³
Sand weight: 82.06 × 100 = 8,206 lbs (4.10 US tons)
Water: 20.51 × 94 × 0.5 = 964 lbs, or about 116 gallons

Twenty-one bags of cement, three cubic yards of sand, and a bit over 100 gallons of water. That’s the shape of a masonry order. The bricks and the sand will arrive on pallets and in a bulk bag; the cement will come on a pallet of bags. The water usually comes from a hose.

What Is the Correct Mortar Mix Ratio?

Standard brick and block walls use 1:4 (one part cement to four parts sand by volume). Structural work and below-grade walls call for 1:3. Light-duty garden walls and non-load-bearing partitions are fine with 1:5 or 1:6.

Mix Ratio	Cement : Sand	Typical Use
1:2	Strongest	Structural, severe exposure
1:3	Strong	Load-bearing, below grade
1:4	Standard	Most brick and block walls
1:5	Medium	Light-duty block, interior work
1:6	Lightest	Garden walls, non-structural

The ratio is by volume, not weight. A “1:4” mix means one bucket of cement to four buckets of sand, not one pound to four pounds. That distinction trips up people who are used to mixing concrete, where the ratio is also by volume but the aggregate is much heavier.

Frequently Asked Questions

How much mortar do I need for a brick wall?

It depends on the joint volume, which is roughly 0.008 ft³ of wet mortar per standard brick. A 1,050-brick wall needs about 67 ft³ of wet mortar, which becomes 103 ft³ dry once the 1.33 factor and 15% waste are applied.

What is the correct mortar mix ratio for brick?

One to four is the standard for most brick walls. Stronger 1:3 mixes are for structural or below-grade work. Lighter 1:5 and 1:6 mixes are for garden walls and interior partitions where load isn’t a concern.

How many bags of cement do I need for 100 bricks?

About one bag for a single-wythe wall with 3/8″ joints and a 1:4 mix. Wider joints or thicker walls push that toward two bags per 100 bricks. Block walls use far less cement per unit.

What is the standard mortar joint thickness?

Three-eighths of an inch. Narrower joints are hard to tool and don’t accommodate normal brick size variation. Wider joints waste mortar and weaken the bond. Pick a width and hold it consistent across the wall.

How much sand do I need for mortar?

Sand is 80 percent of a 1:4 dry mortar mix by volume. A wall using 100 ft³ of dry mortar takes about 80 ft³ of sand, which is roughly 3 cubic yards or 8,000 lbs. Sand weighs about 100 lb/ft³.

What’s the difference between mortar and cement?

Cement is the powder. Mortar is the mixed product of cement, sand, and water. You buy cement in bags and sand in bulk, then mix them on site. Cement alone is not masonry mortar.

How much water goes into mortar?

Water is based on the cement weight, not the sand. At a 0.5 water-cement ratio, an 80 lb batch of cement takes about 40 lbs of water, or roughly 4.8 gallons. Damp sand reduces the amount you actually add.

How many bricks are in a square foot of wall?

About 6.5 standard bricks per square foot with 3/8″ joints. That’s based on a face area of 0.1526 ft² per brick once the joint is included. Larger brick or wider joints reduce the count.

Can I use this calculator for a block wall?

Yes. Pick 8″, 6″, or 4″ concrete block from the masonry type dropdown and the dimensions update. Mortar joint width, mix ratio, and cost inputs all work the same way.

Why does my mortar volume look so high?

The 1.33 dry volume factor and the 15% waste both inflate the wet volume. Check the mix ratio next, then the joint width. A 3/8″ joint entered as 3.75″ gives ten times the volume.

Disclaimer

This mortar calculator estimates wet and dry mortar volume, cement bags, sand, and water from the wall dimensions, unit size, joint width, and mix ratio you enter. Real-world mortar use varies with brick absorption, joint consistency, and how much material is lost during placement. Cement and sand densities are industry averages, not measurements of your specific materials. For structural walls, below-grade work, or anything covered by a building code, have a licensed mason or engineer review the mix design before you order. Cost output is a planning figure and excludes delivery, taxes, and labor.