Calculate cement bags (50kg / 94lb) and sand volume based on target mix ratios, wet volume, and dry compaction factors.
Proportioning fine sand aggregate and cement bags with 1.33 / 1.54 dry expansion factors.
Proportioning fine sand aggregate and cement bags with 1.33 / 1.54 dry expansion factors.
Mathematical formulas and engineering constants powering this calculator.
Compensates for volume reduction as water fills void spaces between sand particles.
Calculates constituent sand volume according to batch proportions.
Converts dry cement volume to 50 kg / 94 lb standard bags.
When dry cement and sand are mixed with water, the fine cement particles fill the voids between sand grains, resulting in a volume reduction of about 33% for mortar and 54% for concrete. Therefore:
Dry Volume = Wet Volume × 1.33 (Mortar) or 1.54 (Concrete)
Sand Volume = Dry Volume × (Sand Parts ÷ Total Ratio Parts)
Common questions on sand-to-cement ratios, dry factors, and bag requirements.
Common construction mix proportions include:
• 1:3 Mix: High-strength exterior rendering & waterproof plaster.
• 1:4 Mix: Load-bearing brickwork mortar & floor screeds.
• 1:5 / 1:6 Mix: Internal wall plastering and non-load-bearing masonry.
• 1:2:4 (M15) Concrete: Foundations, slabs, and lintels (1 cement : 2 sand : 4 gravel).
Dry sand and cement contain microscopic voids. When water is added, the cement dissolves and settles into void spaces, shrinking wet volume by 33% in mortar and 54% in concrete. The multipliers (1.33 and 1.54) convert finished wet volume into the required dry bulk materials.
For a 1:4 mortar mix, 1 cubic meter of sand requires approximately 7 to 8 bags of cement (50 kg each). For a rich 1:3 mix, approximately 9 to 10 bags of cement are needed per m³ of sand.
The standard water-cement (W/C) ratio is 0.45 to 0.55. For one 50 kg bag of cement, add approximately 22.5 to 27.5 liters (6 to 7 US gallons) of clean potable water. Too much water dilutes compressive strength.