Gravel Calculators
Concrete Mix Ratio Calculator (Sand, Gravel, Cement)
Enter your target concrete volume, pick a mix ratio, and get bags of cement plus volumes of sand and gravel. Ratios are by volume — the way field mixes are actually measured.
About this calculator
Accuracy and limitations
Volume ratios only — this is not an engineered mix design. Structural concrete needs a tested design with controlled water-cement ratio.
When this calculator may not be appropriate
This tool is for project planning only. It is not intended for engineering design, official or legal documentation, regulatory filings, or contractor bids without quantities verified with a supplier or qualified professional.
Why trust this tool?
- The formula and the density figure are shown with every result, so you can check the math yourself.
- Built and reviewed by ianwelkins, who maintains every tool on this site.
- The full method is published on the methodology page.
What each ratio is typically used for
| Ratio | Character | Typical use |
|---|---|---|
| 1 : 2 : 3 | General purpose | Paths, small slabs, posts, general repair |
| 1 : 2 : 4 | Standard / economical | Footings, fills, non-critical work |
| 1 : 1.5 : 3 | Stronger | Slabs, steps, surfaces needing durability |
| 1 : 3 : 4 | Lean | Bedding, blinding, mass fill |
Worked example: one cubic yard (27 ft³) of 1:2:3 concrete divides into 6 equal parts: 6.9 ft³ cement = 6.9 94-lb bags (423 lb), 9 ft³ sand (0.33 yd³ ≈ 0.45 t), and 13.5 ft³ gravel (0.5 yd³ ≈ 0.71 t). Water goes in gradually — roughly half as much as cement by weight for a workable mix. In practice, mixes often run 5–6 bags per yard once yield loss is accounted for — the calculator gives the clean-ratio figure.
Related tools & guides
Concrete mix FAQ
What is the best concrete mix ratio?
For general-purpose work, 1:2:3 (cement : sand : gravel) is the common all-rounder; 1:2:4 suits non-critical fills and footings; 1:1.5:3 leans stronger for slabs and steps. Ratios are by volume. For structural concrete, use an engineered mix design instead of a rule-of-thumb ratio.
How many bags of cement for 1 cubic yard of concrete?
A 1:2:3 mix for one cubic yard (27 ft³) takes about 7 of the 94-pound bags of cement, plus roughly 14 ft³ of sand and 21 ft³ of gravel, using the standard 1.54 dry-volume factor. The calculator converts any target volume into all three.
Are the ratios by volume or weight?
By volume — shovel-to-shovel or bucket-to-bucket. That's how field mixes are actually measured. Weight-based mix designs are a different, more precise system used in engineered concrete.