Concrete Mix Ratio Calculator
Mixing from raw materials instead of bagged mix? Pick the ratio and the finished volume; get cement bags, sand, and gravel — already adjusted for dry-volume shrinkage.
Ratio guide
| Ratio | Approx strength | Use |
|---|---|---|
| 1:2:3 | 3,000–4,000 PSI | Slabs, driveways, general work |
| 1:2:4 | 2,500–3,000 PSI | Footings, mass concrete |
| 1:3:6 | ~1,500 PSI | Blinding, non-structural fill |
Strength depends as much on water content and curing as on ratio — keep water at 5–5.5 gal per cement bag and keep the pour damp for the first week.
Common questions
What is the best concrete mix ratio?
The general-purpose ratio is 1 : 2 : 3 (cement : sand : gravel), which yields roughly 3,000–4,000 PSI with proper water content. 1:2:4 suits mass fills and footings; 1:3:6 is lean mix for blinding and non-structural fill.
How many bags of cement per yard of concrete?
A 1:2:3 mix needs about 7 bags of 94 lb Portland cement per cubic yard, with roughly 14 cu ft of sand and 21 cu ft of gravel. The calculator scales any ratio to your volume.
Why multiply by 1.54?
Dry ingredients compact when mixed with water — sand and cement fill the voids between gravel. You need about 1.54 cubic feet of dry materials for every cubic foot of finished concrete.
How much water goes in the mix?
Target a water-to-cement ratio of 0.45–0.55 by weight — about 5 to 5.5 gallons per 94 lb bag of cement. More water means easier placing but measurably weaker concrete. See our water per bag guide.