How this calculator works
Concrete is cement, sand and gravel in a ratio by volume, plus water. The dry materials take up about 1.54 times the finished volume, because the water and the cement fill the gaps between the aggregates. Split that dry volume in the ratio. A 94 lb bag of cement is about one cubic foot, so the cubic feet of cement are the bags.
Worked example: one cubic yard (27 ft³) of 1:2:4 concrete with 10% extra needs 45.7 ft³ of dry materials: 7 bags of 94 lb cement, 13.1 ft³ of sand (0.65 tons) and 26.1 ft³ of gravel (1.37 tons), with about 37 gallons of water. A stronger 1:2:3 mix needs 8 bags.
Materials per cubic yard of concrete (no waste)
A 94 lb bag of cement is about 1 cubic foot.
| Mix | Cement bags | Sand (ft³) | Gravel (ft³) | Water (gal, 0.5) |
|---|---|---|---|---|
| 1 : 1½ : 3 | 8 | 11.3 | 22.7 | 42.6 |
| 1 : 2 : 3 | 7 | 13.9 | 20.8 | 39.1 |
| 1 : 2 : 4 | 6 | 11.9 | 23.8 | 33.5 |
| 1 : 3 : 5 | 5 | 13.9 | 23.1 | 26.0 |
Tips before you buy
- Measure by volume with the same bucket: one bucket of cement, two of sand and four of gravel is a 1:2:4 mix.
- Use clean, sharp sand and clean gravel. Dirty aggregates weaken concrete.
- Less water gives stronger concrete. Add just enough to make it workable, and do not add water to loosen a batch that has begun to set.
- Cure it by keeping it damp or covered for a week.
- For anything structural, use ready-mix or bagged mix with a stated strength, or a design from your engineer.
Tools & materials for this project
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Frequently asked questions
How many bags of cement per cubic yard of concrete?
About 6 bags of 94 lb for a 1:2:4 mix, and 7 for 1:2:3, with no waste.
What is the mix ratio for concrete?
1:2:4 (cement : sand : gravel, by volume) is the general-purpose mix, about 3,000 psi. 1:2:3 and 1:1½:3 are stronger, and 1:3:5 is lean and used for fill.
How much water do I add to concrete?
Enough for a water-to-cement ratio of about 0.45 to 0.55 by weight: 37 gallons for this batch at 0.5. Less water makes stronger concrete, and wet sand needs less.
How much sand and gravel for a cubic yard of concrete?
11.9 ft³ of sand (0.44 cubic yards) and 23.8 ft³ of gravel (0.88 cubic yards) for 1:2:4, with no waste.
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Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.