Concrete Mix Design Calculator

ACI 211.1 absolute volume method — target PSI to water-cement ratio, aggregate proportions, and batch quantities.

Target Compressive Strength
Mix Parameters
Mix Design Results — Per Cubic Yard
Standard Quality
Mix Ratio (C:S:A:W) 1 : 2.2 : 3.1 : 0.5
— Water (lbs)
— Cement (lbs)
— w/c Ratio
— Fine Agg. (lbs)
— Coarse Agg. (lbs)
— Air Content (%)
— Est. 28-day PSI
— Total Wt (lbs/yd³)
Volume to Batch
≈ 1 cubic yard

Mix design comes from Tab 1 — adjust your design parameters there first.

Unit Prices (Optional)
Batch Quantities
— Cement Bags (94 lb)
— Cement (lbs)
— Sand (tons)
— Gravel (tons)
— Water (gallons)
— Total Volume (yd³)
Cost Estimate
Cement—
Sand—
Gravel—
Water—
Total Estimate—

Click any preset to populate the Mix Designer with typical design parameters for that application.

🚶
3,000 PSI
Sidewalk / Patio

Standard residential flatwork. Good workability with 3–4 in slump. Type I cement, 3/4 in aggregate.

Normal exposureNo air
🚗
3,500 PSI
Driveway

Air-entrained for freeze-thaw durability. Suitable for northern climates with deicer use.

Severe exposureAir-entrained
🏠
3,000 PSI
Foundation Wall

Type II cement for moderate sulfate resistance. Good for most residential foundations.

Moderate exposureType II
🏗️
4,000 PSI
Structural Slab

Garage floors, commercial slabs, parking structures. Air-entrained for durability.

Severe exposureAir-entrained
🪵
2,500 PSI
Post Holes

Wet mix for fence posts and small footings. High slump for easy placement.

Normal exposureWet mix
💪
5,000 PSI
High Strength

Columns, beams, and marine structures. Very low w/c ratio, Type V for sulfate resistance.

Very severeType V

How to Use This Calculator

1
Set target PSI

Pick from the preset strength chips or enter a custom value. For most residential work, 3,000–4,000 PSI covers sidewalks through structural slabs.

2
Choose mix parameters

Select your exposure condition, maximum aggregate size, slump, cement type, and whether air entrainment is required for your climate.

3
Read the design output

The calculator returns water, cement, fine aggregate, and coarse aggregate quantities per cubic yard, plus the w/c ratio and quality indicator.

4
Scale with the Batch Calculator

Switch to Tab 2 and enter your total pour volume. Get bags of cement, tons of aggregate, and gallons of water for your project size.

Key Formulas

W/C Ratio
w/c = Water (lbs) ÷ Cement (lbs)
ACI 318 Table 19.3.3 — lower ratio = higher strength & durability
Cement Content
C = W ÷ (w/c)
Water content divided by the target w/c ratio
28-Day Strength Estimate
f'c ≈ 14,000 × (c/w) − 4,000
Abrams' Law (linearized); c/w is cement-water ratio
Absolute Volume Method
Vtotal = Vcement + Vwater + Vair + VCA + VFA
Sum of absolute volumes = 1 yd³ (ACI 211.1)

Glossary

W/C Ratio
Weight of mixing water divided by weight of cement. The single most important factor controlling concrete strength and durability. Typical range: 0.35–0.65.
Slump
A measure of fresh concrete workability. A higher slump means more fluid concrete. Measured in inches per ASTM C143; affected by water content, admixtures, and aggregate size.
Air Entrainment
Intentional incorporation of tiny air bubbles (4–8% by volume) using surfactant admixtures. Improves freeze-thaw resistance and deicer scaling resistance at a slight strength cost.
Admixture
Any ingredient other than cement, water, and aggregate added to modify concrete properties. Includes water reducers (plasticizers), air-entraining agents, accelerators, and retarders.
Fineness Modulus (FM)
A dimensionless number (typically 2.3–3.1) describing sand particle size distribution. Higher FM = coarser sand = less fine aggregate needed per unit volume.
Absolute Volume
The volume occupied by solid material only, excluding air voids. Used in ACI 211.1 mix proportioning to ensure all ingredients sum to exactly 1 cubic yard of concrete.

Frequently Asked Questions

What is the water-cement ratio?

The w/c ratio is the weight of water divided by the weight of cement. It is the most critical parameter in concrete mix design. A lower ratio (e.g., 0.40) produces denser, stronger, more durable concrete. ACI 318 sets maximum w/c limits based on exposure conditions — 0.45 for freeze-thaw, 0.40 for deicer exposure.

What PSI do I need for a driveway?

Residential driveways typically require 3,500–4,000 PSI. In freeze-thaw climates, use 4,000 PSI with 5–7% entrained air and a maximum w/c of 0.45. For southern climates with no freeze cycles, 3,000 PSI without air entrainment is acceptable.

What does slump mean and how do I choose?

Slump (ASTM C143) measures how many inches a cone of fresh concrete settles when the mold is lifted. Higher slump = wetter, more workable mix. For slabs, 3–4 inches is standard. Pumped concrete typically needs 4–5 inches. Stiff mixes (1–2 inches) are used for precast or heavy structural elements where form pressure is a concern.

How many bags of cement per cubic yard?

Typical mixes use 5–8 bags (94 lb each) per cubic yard. A standard 3,000 PSI mix uses about 6 bags. High-strength mixes (5,000 PSI) need 7–9 bags. This calculator uses the ACI 211.1 method for an exact cement content based on your target w/c ratio and water demand.

When is air entrainment required?

Air entrainment is required by ACI 318 whenever concrete will be exposed to freezing and thawing in a moist condition or to deicing chemicals. This includes driveways, exterior slabs, bridge decks, and retaining walls in northern climates. The recommended air content varies from 3.5–7% depending on aggregate size.

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