How the mortar calculator works
Masonry mortar fills the horizontal and vertical joints between bricks or blocks. This calculator estimates the joint volume from the net wall area, masonry-unit dimensions and joint thickness.
It then applies the selected waste allowance and dry-volume factor before dividing the dry material between cement and sand according to the entered mix ratio.
Step 1: calculate net wall area
Openings can be used for doors, windows and other areas where masonry will not be installed.
Step 2: estimate masonry units
The calculator uses the face dimensions of the masonry unit plus the mortar joint.
The unit count is used for the mortar-volume calculation and is not intended to replace a dedicated ordering estimate.
Step 3: estimate wet mortar volume
The theoretical wall volume is calculated using the masonry unit depth as the wall thickness.
Waste allowance
Real projects can use more mortar than ideal geometry predicts because of dropped material, uneven joints, variations in masonry units, site conditions and workmanship.
The default waste allowance is editable rather than being treated as a universal value.
Dry mortar volume
The volume of dry ingredients needed to produce a given wet mortar volume can differ because particles pack together and voids are filled during mixing.
The calculator starts with a dry-volume factor of 1.33, but it is intentionally editable. Use a value appropriate for the materials, estimating method or specification you follow.
Cement and sand mix ratio
Enter the mortar mix as cement parts and sand parts. For example, a 1:4 mix uses one part cement to four parts sand.
Cement weight and bag count
Cement volume is converted to mass using the entered bulk density.
Both the assumed cement bulk density and bag weight are editable so the estimate can be adapted to local products.
Default brick example
With the default settings, the calculator uses a 5 m × 3 m wall, 215 × 65 × 102.5 mm brick dimensions, 10 mm joints, 10% waste, a dry-volume factor of 1.33 and a 1:4 cement-to-sand mix.
Those inputs produce an estimated wet mortar quantity of about 0.291 m³ after the waste allowance. Changing the wall, brick, joint or mix settings updates the result.
Brick and block presets
The presets are convenience starting points only. Masonry sizes vary by country, manufacturer and product. Check the actual dimensions of the brick or block being used and replace the preset values when necessary.
Hollow blocks
The calculator estimates bed and head-joint mortar from the outside masonry dimensions. It does not calculate grout or concrete used to fill hollow block cores.
Core fill, bond beams, reinforced cells and other structural grout should be estimated separately.
Wall thickness
This calculator assumes the entered masonry-unit depth is also the effective wall thickness for the mortar-volume geometry.
Double-leaf, cavity, multi-wythe or unusual masonry assemblies may require separate estimates for each leaf or a more detailed takeoff.
Related construction calculators
To estimate the number of bricks needed for a wall, use the Brick Calculator.
For concrete masonry units, use the Concrete Block Calculator.
For poured concrete quantities, use the Concrete Calculator.
Mortar use depends on actual unit dimensions, joint profile, workmanship, breakage, site conditions, material properties and project specifications. Use this result as a quantity estimate and verify important orders against project drawings, specifications and supplier information.
Frequently asked questions
How much mortar do I need for a brick wall?
Enter the wall dimensions, brick dimensions, joint thickness and openings. The calculator estimates the volume of mortar in the joints and adds the selected waste allowance.
Does the calculator include cement and sand?
Yes. It converts the wet mortar estimate to dry material volume and divides it between cement and sand using the mix ratio you enter.
Can I change the mortar mix ratio?
Yes. Cement and sand parts are independent inputs, so you can use the ratio appropriate for your project.
Can I use inches and feet?
Yes. Wall dimensions can be entered in feet, openings in square feet and masonry dimensions in inches.
Does this calculate grout inside concrete blocks?
No. The estimate is for masonry-joint mortar. Core grout or concrete fill should be calculated separately.
Using this calculator effectively
The Mortar Calculator estimates masonry-joint mortar from wall area, masonry unit dimensions and joint thickness, then applies waste and dry-volume assumptions to estimate cement, sand and cement bags.
Common uses
- Estimating mortar for brick walls with custom joint thickness and openings.
- Estimating masonry-joint mortar for concrete block walls.
- Converting a mortar volume estimate into cement and sand quantities using an adjustable mix ratio.
Tips for a better estimate
- Use the actual masonry-unit dimensions and joint thickness specified for the project.
- Subtract door, window and other non-masonry openings from the wall area.
- Adjust waste, dry-volume factor, cement density, mix ratio and bag size to match the materials and estimating method being used.
Related calculations
Brick Calculator · Concrete Bag Calculator · Concrete Block Calculator