By Zencalcy Editorial TeamLast reviewed About us
Cement is one ingredient of concrete, not the whole mix. A 1:2:3 mix by volume — one part cement, two sand, three gravel — produces about 3,000 psi concrete and is the standard starting point for slabs and footings. This calculator splits any volume into its three parts and converts cement to bags.
Cement, sand and gravel for a mix ratio you choose.
Cement volume = V × (1 ÷ total parts) Bags = cement mass ÷ bag mass
Cement is taken at 1,500 kg/m³ bulk density and a 94 lb bag holds 42.6 kg. A 1:2:3 mix yields roughly 3,000 psi at 28 days; 1:1½:3 gives about 4,000 psi; 1:3:3 is a leaner 2,500 psi mix for footings.
| Symbol | Meaning |
|---|---|
| V | Total concrete volume. |
| parts | Cement : sand : gravel proportions. |
| bags | Cement bags to buy. |
Cement is one sixth of 1 cu yd, or 0.167 cu yd (4.5 cu ft). At 1,500 kg/m³ that is about 191 kg, or five 94 lb bags.
Continue with the Concrete Calculator, Concrete Block Fill Calculator, Concrete Column Calculator, or the Concrete Stairs Calculator — or browse more cement & concrete and all construction calculators.
About five 94 lb bags for a 1:2:3 mix, or six for a richer 1:1½:3 mix. Ready-mix is cheaper above about 1 cubic yard.
Results use standard construction estimating arithmetic: volumes from measured area and depth, unit weights from published material densities, and code-referenced spans or clearances where the page names a code. Quantities are rounded up to whole saleable units and include the stated waste allowance. These tools are planning aids, not structural design, and do not replace a licensed engineer, a local code check, or a contractor's site measurement.
Reference material used to build and check this calculator:
Last reviewed: September 2026. See how we build and check every tool on the about page.
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Content updated: September 2026