Concrete Mix Calculator

What Is Concrete Mix Design?

This concrete mix calculator is built on the science of concrete mix design — the process of selecting the proportions of Portland cement, fine aggregate (sand), coarse aggregate (gravel or crushed stone), and water to produce concrete with the desired strength, workability, and durability. Mix designs are expressed as ratios by dry volume — for example, a 1:2:4 mix uses 1 part cement, 2 parts sand, and 4 parts gravel. The first number is always cement; the ratio of the other ingredients to cement determines the final compressive strength.

More cement relative to aggregate produces stronger concrete — a 1:1.5:3 mix achieves 4,000–5,000 PSI while a 1:3:6 lean mix may only reach 1,500–2,000 PSI. The water-to-cement (w/c) ratio is equally critical: keeping it at 0.45–0.50 prevents excess water from weakening the concrete by diluting the cement paste. Never add water to a mix to make it easier to place — it reduces strength and long-term durability.

How to Use This Concrete Mix Calculator

This concrete mix calculator takes two inputs — the volume of concrete you need and the mix design (cement:sand:gravel ratio) — and instantly returns the quantities of each dry material. Start by entering your concrete volume in cubic yards (the output from our concrete slab calculator or concrete yard calculator). Then choose a standard mix preset or enter a custom ratio. The results update immediately with cement bags, sand and gravel in both tons and cubic feet, and water in gallons.

Concrete Mix Ratios Explained

A concrete mix ratio expresses the proportions of cement, sand, and coarse aggregate (gravel) by dry volume. The first number is always cement; the second is fine aggregate (sand); the third is coarse aggregate (gravel or crushed stone). More cement relative to aggregate means stronger concrete — and higher cost.

1:2:4 — General Purpose Mix

The 1:2:4 mix is the most widely used ratio for residential construction. It produces concrete in the 2,500–3,000 PSI range, which is adequate for sidewalks, patios, non-structural slabs, and footings for light structures. The relatively high aggregate-to-cement ratio keeps material costs lower than structural mixes.

1:2:3 — Structural Mix

With more cement relative to aggregate, the 1:2:3 mix delivers 3,500–4,000 PSI concrete. Use it for driveways, garage floors, basement slabs, and any pour that will carry vehicle loads or support structural weight. Most residential driveways that need to last 20+ years should use a 1:2:3 or richer mix.

1:1.5:3 — High-Strength Mix

The 1:1.5:3 mix produces 4,000–5,000 PSI concrete and is used in structural beams, columns, and high-load applications. The high cement content increases cost but provides the durability required for reinforced structural elements.

1:3:6 — Lean / Mass Concrete

The 1:3:6 lean mix is used where structural strength is not the primary requirement — blinding layers under footings, mass concrete fills, and sub-base work. Lower cement content significantly reduces cost, but the resulting concrete may only reach 1,500–2,000 PSI.

How to Calculate Concrete Mix Materials

The key insight is that dry materials compact when mixed with water, so you need more volume of dry ingredients than the final volume of wet concrete. The standard compaction factor is 1.54 — meaning you multiply the wet concrete volume by 1.54 to get the total dry volume required.

For a 1:n:m mix (cement:sand:gravel), the formula is:

Total dry volume = wet concrete volume × 1.54
Sum of parts = 1 + n + m
Cement (ft³) = (1 ÷ Sum) × Total dry volume
Sand (ft³) = (n ÷ Sum) × Total dry volume
Gravel (ft³) = (m ÷ Sum) × Total dry volume
Water (gal) = Cement weight (lbs) × w/c ratio ÷ 8.34

Step-by-Step Example: 1 yd³ of 1:2:4 Mix

1. Convert wet volume to ft³: 1 yd³ × 27 = 27 ft³
2. Apply compaction factor: 27 × 1.54 = 41.58 ft³ dry volume
3. Sum of parts: 1 + 2 + 4 = 7
4. Cement: (1 ÷ 7) × 41.58 = 5.94 ft³ ≈ 5.94 bags (1 bag = 1 ft³ loose)
5. Sand: (2 ÷ 7) × 41.58 = 11.88 ft³ × 100 lb/ft³ ÷ 2000 = 0.59 tons
6. Gravel: (4 ÷ 7) × 41.58 = 23.76 ft³ × 105 lb/ft³ ÷ 2000 = 1.25 tons
7. Water: 5.94 × 94 lbs × 0.45 ÷ 8.34 = ~30 gallons

Site-Mixed vs. Ready-Mix Concrete

This concrete mix calculator is designed for site-mixed concrete — projects where you buy dry Portland cement, sand, and gravel separately and mix them on-site using a mixer or by hand. Site mixing makes sense for small pours (under 0.5 yd³), remote locations, or when precise control over the mix design is required.

For larger pours, ready-mix concrete ordered from a batch plant by the cubic yard is almost always more cost-effective and less labor-intensive. Ready-mix is consistently batched, arrives ready to pour, and eliminates the need to source and store dry materials. Use our concrete yard calculator to determine how many yards to order, and our concrete bag calculator for pre-bagged mixes like Quikrete or Sakrete on very small jobs.

When to Use Each Method

• Site mix from dry materials — pours under 0.5 yd³, no ready-mix truck access, custom mix designs for special projects
• Pre-bagged concrete (Quikrete / Sakrete) — fence posts, repair patches, very small slabs under 10 sq ft
• Ready-mix truck — any slab over 1 yd³, driveways, foundations, garage floors — more economical and consistent

How Much Do Concrete Mix Materials Cost?

The cost of site-mixed concrete depends on current prices for Portland cement, sand, and gravel in your area. As of 2026, typical prices are:

• Portland cement — $13–$18 per 94 lb bag; roughly $340–$475 per ton
• Sand (fine aggregate) — $25–$50 per ton delivered, or $40–$60 per cubic yard
• Gravel (coarse aggregate) — $30–$55 per ton delivered, or $45–$65 per cubic yard
• Water — negligible cost from a hose; about 30–35 gallons per cubic yard of concrete

For a 1:2:4 general-purpose mix, expect to spend $180–$250 per cubic yard in raw materials when mixing on-site. By comparison, ready-mix concrete delivered by truck costs $130–$165 per cubic yard but requires a minimum order of 3–10 yards depending on the supplier. For small jobs under 0.5 cubic yards, site mixing or pre-bagged concrete is usually cheaper despite the higher per-yard material cost, because you avoid short-load fees that can add $50–$100 per yard on small ready-mix orders.