Cement Calculator
Calculate how many bags of pure cement are needed for a given volume of concrete or mortar, based on a mix ratio.
About the Cement Calculator
This calculator estimates how many bags of pure Portland cement are needed to hand-mix a batch of concrete or mortar at a chosen ratio of cement to sand to aggregate, rather than buying pre-blended bags.
Formula: Dry Volume = Wet Volume × 1.54 (dry ingredients occupy more volume before mixing than the finished wet mix); Cement Volume = Dry Volume × (Cement Parts ÷ Total Parts); Bags = Cement Volume ÷ 1 cu ft (a standard 94 lb bag of Portland cement yields about 1 cu ft)
A 1:2:4 ratio is a common general-purpose mix for slabs and footings; richer 1:1.5:3 mixes suit structural work, while leaner 1:3:6 mixes suit mass fill. Always buy a few extra bags to cover spillage and measurement variation.