Concrete Mix Ratio Calculator: Cement, Sand and Gravel Quantities
This mix ratio calculator breaks your total concrete volume into the cement, sand, and gravel needed for a 1:2:3 or 1:2:4 mix. It's ideal for mixing your own concrete on site and knowing exactly how much of each material to buy.
Estimated concrete
Estimates only. Add ~5–10% for waste. Bag yields: 40 lb ≈ 0.30, 60 lb ≈ 0.45, 80 lb ≈ 0.60 cu ft. Concrete ≈ 150 lb per cu ft.
How to Use the Concrete Mix Ratio Calculator
- 1
Enter your dimensions
Type the length, width and thickness of your slab, footing or pad and choose your units, feet, inches or meters.
- 2
Get instant volume
See the result in cubic yards, cubic feet and cubic meters, plus weight, the moment you type, no page reloads.
- 3
Buy the right amount
We convert volume into the exact number of 40, 60 and 80 lb bags, truck loads and cost so you order without waste or shortfalls.
The formula
Dry_ft³ = Wet_ft³ × 1.54; one_part = Dry_ft³ ÷ (c + s + g); cement = 1×part, sand = s×part, gravel = g×part
- ·Wet_ft³ = finished concrete volume (ft³)
- ·1.54 = dry-to-wet bulking factor
- ·c : s : g = cement : sand : gravel ratio
- ·one_part = volume of a single ratio part (ft³)
- ·94 lb sack ≈ 1 ft³ of cement
Split the dry volume by the sum of the ratio parts to get the size of one part, then scale each ingredient. Divide the cement volume by 1 ft³ to get 94 lb sacks.
Worked examples
Example 1: 10 ft³ of 1:2:3 concrete
- Dry volume = 10 × 1.54 = 15.4 ft³
- One part = 15.4 ÷ 6 = 2.57 ft³
- Cement 2.57, sand 5.13, gravel 7.70 ft³
- Cement sacks = 2.57 → 3 sacks
Result: About 2.6 ft³ cement, 5.1 ft³ sand, 7.7 ft³ gravel
Example 2: One cubic yard of 1:2:4 concrete
- Wet = 27 ft³; dry = 27 × 1.54 = 41.58 ft³
- One part = 41.58 ÷ 7 = 5.94 ft³
- Cement 5.94, sand 11.88, gravel 23.76 ft³
- Cement sacks = 5.94 → 6 sacks
Result: About 6 sacks cement, 11.9 ft³ sand, 23.8 ft³ gravel
Concrete calculators by project type
Concrete bag yield & coverage
How much mixed concrete a standard bag yields, and how far a cubic yard goes at common slab depths.
| Bag size | Yield (cu ft) | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 | 90 |
| 60 lb | 0.45 | 60 |
| 80 lb | 0.60 | 45 |
- 40 lb
- 60 lb
- 80 lb
Related guides
Concrete Mix Ratio FAQs
What is a 1:2:3 concrete mix ratio?
A 1:2:3 mix is 1 part cement, 2 parts sand, and 3 parts gravel by volume. It's a common general-purpose mix that reaches around 3000 psi.
What mix ratio should I use for footings?
A 1:2:4 mix (1 part cement, 2 parts sand, 4 parts gravel) is a common choice for footings and general foundation work.
How much cement, sand, and gravel for 1 cubic yard?
For a 1:2:3 mix, the dry materials total more than the finished yard because of voids; plan on roughly 6 bags of cement plus about 0.5 yard of sand and 0.8 yard of gravel per cubic yard.
What is the strongest concrete mix ratio?
Richer mixes with more cement, such as 1:1.5:3, are stronger than leaner ones like 1:2:4. Lower water content also increases strength.
Do the mix ratios go by volume or weight?
For on-site hand mixing, the classic 1:2:3 and 1:2:4 ratios are measured by volume, such as shovels or buckets, not by weight.
How much water do I add to a concrete mix?
Use enough water for a plastic, workable mix, typically a water-to-cement ratio near 0.5; too much water weakens the finished concrete.
What is a 1:2:4 concrete mix used for?
A 1:2:4 ratio (one part cement, two sand, four gravel) is a general-purpose mix good for about 2,500 to 3,000 PSI, suitable for footings, non-structural slabs, and paths. It uses less cement than a 1:2:3 mix, so it is cheaper but slightly weaker. Step up to 1:2:3 for driveways and load-bearing slabs.
What does the first number in a mix ratio represent?
The first number is always the cement portion, followed by sand then gravel (coarse aggregate). So 1:2:3 means one part cement to two parts sand to three parts gravel, measured by volume. Water is added separately and is not part of the three-number ratio.
Why do I multiply wet volume by 1.54?
Dry sand, cement, and gravel have air gaps between particles, and when you add water the mix compacts as those voids fill. Multiplying the finished (wet) volume by about 1.54 accounts for that bulking, so you buy enough dry material. Skipping this factor leaves you short of ingredients.
What mix ratio is best for a driveway?
A 1:2:3 mix is the usual choice for driveways because it targets roughly 3,000 to 3,500 PSI, which handles vehicle loads. For heavier trucks or freeze-thaw regions, some pours go richer. Whatever ratio you pick, keep the water content low for durability.
Does adding more water weaken concrete?
Yes, and significantly. Extra water increases the water-to-cement ratio, leaving more pore space as it evaporates, which lowers strength and invites cracking. Add only enough water for a workable, plastic mix; if it is too stiff, adjust with a plasticizer rather than a bucket of water.
What is the difference between a mortar mix and a concrete mix?
Mortar is just cement and sand (no gravel) used to bond blocks and bricks, while concrete adds coarse gravel for structural strength. Because mortar has no aggregate, it is weaker in compression but stickier and more workable. Do not substitute one for the other in a structural pour.
How do I convert a mix ratio into bags of cement?
Find the cement volume from the ratio, then divide by the volume of your bag: a 94 lb Portland sack is about 1 ft³. For example, 5.94 ft³ of cement equals about 6 sacks. If you use pre-blended bagged concrete instead, the ratio is already set and you only add water.