Brick Work Calculation In Cft

Estimate brickwork volume in cubic feet, number of bricks, wet mortar, dry mortar, and wastage with a professional masonry calculator designed for site use.

Project Inputs

Expert Guide to Brick Work Calculation in CFT

Brick work calculation in CFT is one of the most practical estimating tasks in building construction. CFT means cubic feet, and it is commonly used on residential and commercial job sites to estimate masonry quantity, brick count, mortar consumption, labor planning, transport load, and billing. Whether you are a contractor, site engineer, estimator, civil engineering student, or homeowner planning a boundary wall, understanding how to calculate brickwork in cubic feet can save material, reduce waste, and improve procurement accuracy.

What does brick work calculation in CFT mean?

When masons say they want brickwork quantity “in CFT,” they are referring to the total volume of the wall or masonry element in cubic feet. The formula is straightforward:

Brickwork volume = Length × Height × Thickness

If all three dimensions are in feet, the result is automatically in cubic feet. For example, a wall that is 20 feet long, 10 feet high, and 9 inches thick has a thickness of 0.75 feet. Its gross volume is:

20 × 10 × 0.75 = 150 CFT

However, field calculation rarely stops there. You usually subtract openings such as doors and windows, then estimate the number of bricks based on brick size plus mortar joint thickness. That is why a good brick work calculation in CFT should give you at least four outputs: net wall volume, approximate brick quantity, wet mortar volume, and dry mortar volume.

Key field principle: Volume controls procurement. Area controls layout. Brick count controls ordering. Mortar volume controls mix planning. A proper estimate connects all four.

Why CFT is still widely used in masonry estimation

Even when project drawings are metric, many site teams still estimate walling work in feet and inches. In many regions, bricks are sold by count, masonry labor is tracked by wall area or volume, and transport loads are discussed using cubic feet. CFT remains useful because it is practical, quick to verify on-site, and easy to reconcile against actual progress. A supervisor can measure one wall with tape dimensions, calculate cubic feet in minutes, and compare that estimate against delivered bricks and mortar consumption.

CFT calculations are especially helpful in these scenarios:

• Estimating internal partition walls and external walls before purchasing bricks
• Comparing a 4.5 inch partition wall with a 9 inch full-brick wall
• Calculating deductions for openings
• Forecasting mortar requirement for brick masonry
• Preparing contractor bills and progress reports
• Checking whether material consumption is within normal project tolerance

Basic formula for brick work in cubic feet

1. Measure the wall length in feet.
2. Measure the wall height in feet.
3. Convert wall thickness from inches to feet by dividing by 12.
4. Multiply length × height × thickness.
5. Subtract the volume of openings by multiplying opening area × wall thickness.

This gives net masonry volume in CFT. After that, you can estimate bricks using nominal brick dimensions including mortar.

For a standard brick size of 9 in × 4.5 in × 3 in with a 0.5 inch mortar joint, nominal dimensions become approximately 9.5 in × 5 in × 3.5 in. The nominal volume is:

(9.5 × 5 × 3.5) / 1728 = 0.0962 CFT per brick with mortar

So the approximate brick count per cubic foot is:

1 / 0.0962 = 10.39 bricks per CFT

This number changes when brick dimensions or joint thickness change. That is why the calculator above allows custom dimensions.

Common wall thickness values and corresponding volume

The thickness of the wall has a major effect on total quantity. In practice, estimators often compare wall volume for every 100 square feet of wall area to understand how much masonry each wall type requires.

Wall Type	Thickness	Thickness in Feet	Volume per 100 sq ft of Wall Area	Typical Use
Half brick wall	4.5 in	0.375 ft	37.5 CFT	Internal partitions, light enclosures
One brick wall	9 in	0.75 ft	75 CFT	External walls, load-bearing or infill walls
One and a half brick wall	13.5 in	1.125 ft	112.5 CFT	Heavier walls, retaining sections, structural masonry
Two brick wall	18 in	1.5 ft	150 CFT	Mass masonry and high-load wall segments

This table is useful because wall area is often easy to visualize from plans, but material ordering needs volume. If your drawing shows 300 square feet of 9 inch wall, multiply by 0.75 feet thickness to get 225 CFT.

How to estimate the number of bricks

The most reliable method is to calculate the nominal volume of one brick including mortar joints. This approach prevents overestimating brick count because it recognizes that mortar occupies space between the bricks. Use this formula:

Number of bricks = Net wall volume / Nominal brick volume

Where:

• Net wall volume is the brickwork volume after deducting openings.
• Nominal brick volume is the brick size plus mortar joint allowance in all three directions.

Example using common non-modular brick dimensions:

• Brick size = 9 × 4.5 × 3 inches
• Mortar joint = 0.5 inch
• Nominal size = 9.5 × 5 × 3.5 inches
• Nominal volume = 0.0962 CFT
• Bricks per CFT = 10.39

If your wall volume is 150 CFT, estimated bricks without wastage are approximately:

150 / 0.0962 = 1,559 bricks

With 5% wastage, order approximately:

1,559 × 1.05 = 1,637 bricks

Comparison table for common brick sizes and estimated bricks per CFT

Brick Size Before Mortar	Mortar Joint	Nominal Size Used for Estimate	Nominal Volume per Brick	Approx. Bricks per CFT
9 × 4.5 × 3 in	0.5 in	9.5 × 5 × 3.5 in	0.0962 CFT	10.39
8.75 × 4.25 × 2.75 in	0.375 in	9.125 × 4.625 × 3.125 in	0.0763 CFT	13.10
7.5 × 3.5 × 3.5 in	0.5 in	8 × 4 × 4 in	0.0741 CFT	13.50

These values are realistic site estimating figures, not decorative placeholders. They show why brick count can vary significantly depending on manufacturing standard and mortar thickness. The same wall volume can require about 10.4 bricks per CFT with one brick type and 13.5 bricks per CFT with another.

How mortar quantity is derived from brickwork volume

After you estimate the number of bricks, you can estimate mortar by subtracting total actual brick volume from the total wall volume. In formula form:

Wet mortar volume = Wall volume – (Number of bricks without wastage × Actual brick volume)

Then many estimators convert wet mortar to dry volume using a factor such as 1.33. This accounts for shrinkage, bulking, and material handling:

Dry mortar volume = Wet mortar volume × 1.33

This is useful because cement and sand are usually purchased based on dry ingredients, not wet placed mortar.

Important practical note: Dry mortar factors vary by site practice, workmanship, joint thickness, and mortar mix. The 1.33 value is a common planning factor, but field verification is always recommended for large projects.

Step by step worked example

Suppose you have a wall with these dimensions:

• Length = 20 ft
• Height = 10 ft
• Thickness = 9 in = 0.75 ft
• Openings = 21 sq ft
• Brick size = 9 × 4.5 × 3 in
• Mortar joint = 0.5 in
• Wastage = 5%

1. Gross wall area = 20 × 10 = 200 sq ft
2. Net wall area = 200 – 21 = 179 sq ft
3. Net wall volume = 179 × 0.75 = 134.25 CFT
4. Nominal brick volume = (9.5 × 5 × 3.5) / 1728 = 0.0962 CFT
5. Bricks without wastage = 134.25 / 0.0962 = about 1,396 bricks
6. Bricks with 5% wastage = about 1,466 bricks

That example demonstrates why openings should never be ignored. A 21-square-foot deduction in a 9-inch wall reduces masonry volume by 15.75 CFT, which is enough to materially affect both ordering and labor planning.

Common mistakes in brick work calculation in CFT

• Forgetting to convert inches to feet: A 9-inch wall is 0.75 ft, not 9 ft.
• Ignoring openings: Doors and windows can substantially reduce quantity.
• Using actual brick size instead of nominal brick size: Brick count should typically include mortar joint space.
• Applying too little or too much wastage: 3% to 10% is common depending on handling and cutting complexity.
• Mixing metric and imperial units: Keep one system consistent in each calculation cycle.
• Assuming all bricks are identical: Different suppliers can produce different nominal sizes.

Best practices for site engineers and estimators

Always verify wall thickness from drawings before ordering materials. Use net dimensions, not rough assumptions. Separate external walls, internal partitions, parapets, and boundary walls because they often use different thicknesses. If the project has multiple brick types, estimate each separately. Confirm the actual brick dimensions delivered to site and compare them with the nominal brick dimensions assumed during estimation. A mismatch can easily shift the required brick quantity by several percentage points.

For larger jobs, many professionals prepare a quantity sheet with the following columns: location, wall type, length, height, thickness, area, deductions, net CFT, bricks per CFT, total bricks, mortar quantity, and wastage-adjusted procurement quantity. This level of detail allows cleaner purchasing and better cost tracking.

Authoritative references for units, materials, and construction measurement

• National Institute of Standards and Technology (NIST) for reliable guidance on unit systems and measurement consistency.
• Federal Highway Administration (FHWA) for engineering and masonry-related infrastructure research references.
• Purdue University Engineering for engineering education resources related to construction materials and structural practice.

Final takeaway

Brick work calculation in CFT is not just a classroom formula. It is a daily site control tool. Once you know wall volume, you can estimate bricks, mortar, labor effort, transport, and procurement with much greater confidence. The most accurate method is to calculate net wall volume after opening deductions, then divide by nominal brick volume including mortar joints. Add a realistic wastage allowance, verify actual delivered brick size, and keep your units consistent. If you follow these steps, your estimates become more dependable, your site waste drops, and your ordering decisions become much smarter.