What is the 1:2:3 concrete mix ratio?

The 1:2:3 concrete mix ratio means 1 part cement : 2 parts sand : 3 parts coarse aggregate (gravel) by volume or weight. This is a standard mix that produces approximately 3,000 PSI (20 MPa) compressive strength after 28 days of curing. It is suitable for footings, slabs, sidewalks, and light structural work. The water-cement ratio should be kept between 0.45 and 0.55 by weight for this mix.

How much water do I add to concrete mix?

Water is specified as a water-cement (W/C) ratio by weight. A W/C ratio of 0.45–0.55 is standard for most applications. For a 94 lb (1 US bag) of cement at W/C = 0.50, you add 94 × 0.50 = 47 lbs of water ≈ 5.6 gallons. Less water (lower W/C) increases strength but reduces workability; more water makes the mix easier to pour but weakens the final concrete.

What PSI concrete do I need for a driveway?

Residential driveways typically require 3,000–4,000 PSI (20–28 MPa) concrete. A 1:2:3 mix produces about 3,000 PSI, adequate for light passenger vehicles. A 1:1.5:3 mix reaches about 4,000 PSI and is better for driveways with heavy trucks or regular vehicle traffic. Cold climates with freeze-thaw cycles should use 4,000 PSI minimum with air entrainment to resist surface scaling.

Concrete Mix Ratios Guide: 1:2:3, Water-Cement Ratio & PSI Strength

What Concrete Mix Ratios Mean

A concrete mix ratio describes the proportion of the three main dry ingredients — cement, fine aggregate (sand), and coarse aggregate (gravel or crushed stone) — by volume or by weight. The format is cement : sand : gravel. A lower cement fraction increases strength but costs more; a higher aggregate fraction reduces cost but lowers strength.

Water is added separately and expressed as a water-cement (W/C) ratio by weight. Every 0.05 increase in W/C ratio reduces 28-day compressive strength by approximately 5–8%.

Common Mix Ratios, Strength, and Applications

Mix Ratio (C:S:G)	W/C Ratio	28-Day Strength (PSI)	28-Day Strength (MPa)	Typical Use
1:3:6	0.60	~2,000	~14	Lean fill, non-structural mass concrete
1:2:4	0.55	~2,500	~17	Light footings, landscaping walls
1:2:3	0.50	~3,000	~20	Slabs, sidewalks, driveways, footings
1:1.5:3	0.45	~4,000	~28	Structural slabs, columns, beams
1:1:2	0.40	~5,000	~34	High-strength structural, precast

Cement Bags Needed Per Cubic Yard and Cubic Meter

One US bag of Portland cement weighs 94 lbs (42.6 kg). One cubic yard of concrete = 27 cubic feet. One cubic meter = 35.31 cubic feet. The bags needed vary by mix ratio because leaner mixes use more aggregate relative to cement.

Mix Ratio	Bags of Cement per Cubic Yard	Bags of Cement per Cubic Meter
1:3:6	4.0 bags	5.2 bags
1:2:4	5.0 bags	6.5 bags
1:2:3	5.7 bags	7.5 bags
1:1.5:3	6.8 bags	8.9 bags
1:1:2	9.0 bags	11.8 bags

Water-Cement Ratio and Workability

The W/C ratio is the single most important factor controlling concrete strength. Lower ratios (0.40–0.45) produce stronger, denser concrete but require more mixing effort and may need a plasticizer (superplasticizer) additive to maintain workability. Ratios above 0.60 make the mix easy to pour but significantly weaken the hardened concrete and increase shrinkage cracking.

Use our volume converter to convert between cubic yards, cubic meters, and cubic feet when ordering ready-mix concrete or estimating aggregate quantities.