Cement Mortar Mix Calculator
Calculate cement bags and sand needed for a mortar mix ratio.
Assumptions used in this calculation
- Standard bag size: Assumes a standard 50kg cement bag with a volume of 1.25 cubic feet and a dry-to-wet volume factor of 1.33.
About this calculator
Ordering mortar materials means working through two conversions most people skip when estimating by hand, converting wet mortar volume into dry material volume, and then splitting that dry volume by your mix ratio into cement and sand quantities. This calculator takes your total wet mortar volume, applies a standard 1.33× dry volume factor to account for the compaction that happens once dry ingredients are mixed with water, splits the resulting dry volume by your cement:sand ratio parts, and converts the cement portion into standard 50kg bags using a 1.25 cubic foot bag volume. Enter total volume and your ratio parts, and get a bag count ready for ordering instead of doing the volume conversion and ratio split by hand. Because richer mixes (a higher proportion of cement, like 1:3 versus 1:6) need proportionally more cement bags for the same total volume, use the ratio your job specification actually calls for rather than a generic default.
Worked example
100 cu ft mortar, 1:4 cement:sand ratio
Result: ≈ 22 cement bags
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