Concrete Block Calculator: How Many Blocks Do You Need?

How to Use the Concrete Block Calculator

This calculator gives you a solid estimate on the number of concrete blocks (also called concrete masonry units or CMUs if you want to know the technical terminology) you'll need for projects like building a retaining wall, garden wall, basement, a garage, or other project. Plan your project by calculating the number of blocks, mortar, and sand needed based on wall dimensions and your selected block size.

Step 1: Choose Your Calculation Method

The calculator gives you two ways to find out how many concrete blocks you need.

• Calculate by Wall Dimensions: Enter the height and width of your rectangular wall area.
• Calculate by Area with Openings: Enter the wall dimensions and subtract openings like windows and doors for a more accurate estimate.

Step 2: Enter Your Measurements

Input your wall measurements using your preferred units (feet, inches, yards, meters, or centimeters). Be precise with your measurements to get the most accurate results.

Step 3: Choose Your Block Size

Choose the type of concrete block you plan to use.

• 4" x 8" x 16": Lightweight blocks for non-load-bearing walls or partitions.
• 6" x 8" x 16": Medium-weight blocks for structural walls with moderate load requirements.
• 8" x 8" x 16": Standard blocks for load-bearing walls and structural applications.
• 10" x 8" x 16": Heavy-duty blocks for thicker structural walls.
• 12" x 8" x 16": Extra heavy-duty blocks for maximum structural integrity.
• Half Blocks: 8" x 8" x 8" blocks for corners and special applications.
• Sash Blocks: Specialized blocks with grooves for window frames.
• Lintel Blocks: U-shaped blocks for creating support beams over openings.
• Custom Size: Enter your own block dimensions for specialty blocks.

Step 4: Add Openings (if applicable)

If you're using the "Calculate by Area with Openings" method, you can add windows, doors, and other openings to your wall. This allows the calculator to subtract these areas from your total, giving you a more accurate estimate and maybe even saving you a little money.

Step 5: Enter Block Price (Optional)

To get cost estimates, you can enter the price per concrete block. The calculator will then provide a total material cost estimate for your project. If no price is entered, the tool will return an estimate based on the average price range of $1 - $4 per concrete block according to Estimate Florida Consulting.

Step 6: Calculate and Review Results

Click "Calculate Concrete Blocks" to get each of the results listed below.

• Number of concrete blocks needed for the project.
• Mortar and sand requirements.
• Wall area measurements and net area (when accounting for openings).
• Estimated material weight.
• Estimated construction time based on block size.
• Detailed cost breakdown for blocks, mortar, and sand.
• Information about your selected block type.

Common Concrete Block Applications

Different projects require specific block types to ensure proper function and durability. Here are some examples.

Step-by-Step Calculation Example

Let's walk through a real-world example to demonstrate how the calculator works. Imagine we're building a garage wall that's 10 feet high by 20 feet wide using standard 8" x 8" x 16" blocks, with a 3' x 7' door opening.

The key to accurate block estimates lies in using the actual block dimensions (not nominal) and accounting for openings in your wall. Remember that concrete blocks have standard dimensions, but their actual sizes are slightly smaller to allow for mortar joints.

Planning other construction projects? You might also find these calculators helpful: Gravel Calculator for walkways and driveways or Sand Calculator for backyard projects.