Instantly calculate the correct cement, sand, gravel (coarse aggregate), and water quantities for any concrete mix ratio — 1:2:3, 1:1.5:3, ACI 211.1 mix design — in bags, pounds, cubic feet, and cubic yards for slabs, driveways, footings, columns, and foundations.
Enter your concrete volume or slab dimensions and select a mix ratio to get a full material breakdown.
Choose volume for direct entry, or slab to calculate volume from dimensions.
1 cubic yard = 27 cubic feet · standard ready-mix truck = 8–10 cubic yards.
ACI 211.1 standard mix · ~5.7 bags cement/yd³ · w/c 0.50 · 3,500–4,000 PSI at 28 days.
Lower w/c = higher strength but less workability. ACI 318 max w/c = 0.45 for exposure to freezing/thawing.
3/4-in (#67) gravel per ASTM C33 is the most common size for residential and commercial ready-mix in the USA.
Type I/II Portland cement per ASTM C150 is standard for all residential and commercial concrete in the USA.
Always order 10% extra to account for spillage, uneven subgrade, and form variation.
The concrete gravel ratio (also called the aggregate-to-cement ratio or the concrete mix ratio) defines how much coarse aggregate (gravel or crushed stone) is combined with cement, fine aggregate (sand), and water to produce concrete of a specified strength and workability. In the USA, concrete mixes are expressed as a cement:sand:gravel ratio by volume — the most common being 1:2:3, meaning for every 1 part Portland cement, you use 2 parts sand and 3 parts gravel. Per ACI 211.1, the ratio of coarse aggregate to total aggregate (the coarse aggregate fraction) is one of the most important variables in mix design — higher gravel content improves compressive strength, reduces shrinkage, and lowers cost (gravel is cheaper than cement), but reduces workability if excessive. The correct gravel ratio also depends on the maximum aggregate size per ASTM C33 — larger aggregate (3/4 in to 1.5 in) allows higher gravel fractions per ACI 211.1 Table 6.3.6 and produces more economical mixes for large pours.
Per ACI 211.1 "Standard Practice for Selecting Proportions for Normal Concrete", the coarse aggregate content of a concrete mix is determined by the dry-rodded bulk density of the aggregate and the maximum aggregate size relative to the fineness modulus of the sand. For a standard residential mix using 3/4-inch ASTM C33 #67 gravel, ACI 211.1 recommends a coarse aggregate volume fraction of 0.64–0.67 ft³ per ft³ of concrete, which corresponds to approximately 1,860–1,940 lb of gravel per cubic yard of concrete. Increasing gravel content above ACI limits causes segregation (gravel sinks to bottom) and reduces paste coverage of aggregate surfaces — both of which reduce strength. Using less gravel than recommended produces a paste-rich mix that shrinks more on curing and costs more per cubic yard. The 1:2:3 ratio approximates the ACI 211.1 recommended proportions for a 3,500–4,000 PSI mix at a w/c of 0.50.
ASTM C33 "Standard Specification for Concrete Aggregates" defines the gradation requirements for coarse aggregate (gravel or crushed stone) used in concrete in the USA. The most common ASTM C33 gravel sizes for ready-mix and site-mixed concrete are: #67 (3/4 in nominal) — the universal standard for residential and commercial concrete; #57 (1 in nominal) — used for slabs-on-grade and pavements; and #467 (1.5 in nominal) — used for mass concrete and large structural elements. Gravel must be clean, hard, and durable — free of clay coatings, soft particles, and organic material that reduce bond strength between the aggregate and the cement paste matrix.
The water-cement ratio (w/c) is the single most important variable governing concrete compressive strength and durability. Per ACI 318, the maximum w/c is 0.45 for concrete exposed to freezing and thawing or deicers, and 0.50 for general interior / non-exposed concrete. The target w/c for residential driveways and slabs in the USA is 0.45–0.50, producing 3,500–4,500 PSI at 28 days. Never add extra water to improve workability — each 1-gallon increase in mix water per cubic yard reduces 28-day strength by approximately 200–300 PSI. Use a plasticizer (water reducer) to improve workability without increasing the w/c ratio.
A standard bag of Portland cement in the USA weighs 94 pounds (1 cubic foot). The number of bags per cubic yard of concrete depends on the mix design: the 1:2:3 mix requires approximately 5.5–6.0 bags (517–564 lb) of cement per cubic yard. A richer 1:1.5:3 mix requires approximately 6.5–7.0 bags/yd³, while a lean 1:3:6 mix requires only 3.5–4.0 bags/yd³. For small DIY projects, 80-lb bags of pre-mixed concrete (cement + sand + gravel pre-proportioned) yield approximately 0.60 cubic feet per bag — so you need about 45 bags of 80-lb mix per cubic yard. The 1:2:3 site-mix approach is significantly more economical for volumes over 1 cubic yard.
The key principle is that the total volume of dry materials (cement + sand + gravel) is greater than the volume of wet concrete produced — because water fills voids between particles and cement paste fills aggregate voids. A common rule of thumb is that the dry volume of ingredients is approximately 1.54× the wet concrete volume. This 1.54 factor accounts for void filling and the compaction that occurs when dry materials are mixed with water and vibrated. All USA material quantities are based on the dry loose bulk densities of Portland cement (94 lb/ft³), sand (approximately 100 lb/ft³), and gravel (approximately 100–105 lb/ft³).
For volumes under 0.5 cubic yards (small repairs, fence posts, small footings), using pre-bagged concrete mix (Quikrete, Sakrete, or similar — cement + sand + gravel pre-proportioned in 60-lb or 80-lb bags) is the most practical approach — just add water per bag instructions. For volumes of 0.5–1.0 cubic yards, site-mixing cement, sand, and gravel with a rented drum mixer is cost-effective and gives full control over the mix design. For volumes over 1 cubic yard — and especially over 2 cubic yards — ordering ready-mix concrete from a local batch plant is almost always faster, more consistent, and more economical than site-mixing. Specify your required PSI (e.g., 4,000 PSI), slump (4–5 in for residential), max aggregate size (3/4 in), and w/c or air entrainment requirements when ordering ready-mix. Never add water to a ready-mix truck load — this increases the w/c ratio and reduces strength below the specified design value.
The table below provides the standard concrete mix ratios, corresponding compressive strengths, bags of cement per cubic yard, and recommended applications for each mix type used in the USA. All strength values are 28-day compressive strength at w/c 0.45–0.50 using Type I/II Portland cement per ASTM C150 and 3/4-inch ASTM C33 gravel.
| Mix Ratio (C:S:G) | 28-Day Strength | Bags/Cubic Yard | w/c Ratio | Applications | ACI Standard |
|---|---|---|---|---|---|
| 1 : 1 : 2 | 5,000–5,500 PSI | 8.0–8.5 bags | 0.35–0.40 | Structural columns, bridge decks, high-strength beams | ACI 318 |
| 1 : 1.5 : 3 | 4,000–4,500 PSI | 7.0–7.5 bags | 0.40–0.45 | Footings, piers, grade beams, structural slabs | ACI 318 / ACI 332 |
| 1 : 2 : 3 | 3,500–4,000 PSI | 5.5–6.0 bags | 0.45–0.50 | Residential slabs, driveways, sidewalks, stairs | ACI 302.1R / PCA |
| 1 : 2 : 4 | 2,500–3,000 PSI | 4.5–5.0 bags | 0.50–0.55 | Light sidewalks, paths, garden slabs, non-structural fill | ACI 302.1R |
| 1 : 3 : 5 | 2,000–2,500 PSI | 3.5–4.0 bags | 0.55–0.60 | Mass fill, blinding layers, non-structural bases | ACI 211.1 |
| 1 : 3 : 6 | 1,500–2,000 PSI | 3.0–3.5 bags | 0.60–0.65 | Lean concrete / mud mat under footings only | ACI 211.1 |
The table below gives the complete material breakdown — cement bags, sand (lb and tons), gravel (lb and tons), and water (gallons) — per cubic yard of concrete for each standard mix ratio at w/c 0.50. Use this table for quick material ordering estimates before using the calculator for project-specific quantities including waste factor.
| Mix Ratio | Cement (bags) | Cement (lb) | Sand (lb) | Gravel (lb) | Water (gal) |
|---|---|---|---|---|---|
| 1 : 1 : 2 | 8.2 bags | 771 lb | 771 lb | 1,617 lb | 41.0 gal |
| 1 : 1.5 : 3 | 7.1 bags | 667 lb | 1,000 lb | 2,100 lb | 35.4 gal |
| 1 : 2 : 3 | 5.8 bags | 545 lb | 1,090 lb | 1,715 lb | 30.6 gal |
| 1 : 2 : 4 | 4.9 bags | 461 lb | 922 lb | 1,936 lb | 25.9 gal |
| 1 : 3 : 5 | 3.7 bags | 348 lb | 1,044 lb | 1,827 lb | 19.5 gal |
| 1 : 3 : 6 | 3.2 bags | 301 lb | 903 lb | 1,888 lb | 16.9 gal |
Getting the gravel ratio and water-cement ratio right is the foundation of durable concrete. The ACI 211.1 Standard Practice for Selecting Proportions for Normal Concrete and the PCA Design and Control of Concrete Mixtures are the two definitive references for all concrete mix design in the USA.
Concrete slump measures workability — how fluid and placeable the mix is — tested per ASTM C143 using a standard slump cone. The target slump for most residential concrete in the USA is 4–5 inches: enough to flow into forms and around rebar, but not so fluid that water rises to the surface (bleeding) or aggregate segregates. A slump over 6 inches almost always indicates excess water — do not accept a ready-mix delivery with slump above specification. Slump can be increased without raising w/c by using a Type A water-reducing admixture (plasticizer) such as ASTM C494 compliant Polyheed or Pozzolith, which are standard in most ready-mix formulations in the USA.
In the USA's freeze-thaw climate zones (roughly the northern half of the country), concrete exposed to freezing temperatures and deicing salts requires air entrainment — tiny microscopic air bubbles deliberately introduced into the mix using an ASTM C260 air-entraining admixture. The ACI 318 target air content for 3/4-inch aggregate concrete in severe exposure is 6 ± 1%. Air entrainment allows the concrete to survive freeze-thaw cycles by providing microscopic pressure-relief chambers for ice crystal expansion. Never specify 3,500 PSI or less for an outdoor slab in a freeze-thaw zone — use at least 4,000 PSI with 6% air and a maximum w/c of 0.45, per ACI 318 Table 19.3.3.
Sand and gravel stockpiles at job sites typically contain absorbed and surface moisture that must be accounted for when calculating the actual water added to the mix. Standard practice per ACI 211.1 is to measure aggregate moisture per ASTM C566 and subtract surface moisture from the mix water quantity. Typical surface moisture in sand is 2–6% by weight, and in gravel 0.5–2%. Failing to account for aggregate moisture causes the actual w/c to exceed the design w/c, reducing strength. For large ready-mix plants, moisture probes in the sand bin automatically adjust batch water quantities in real time — a capability not available on small job sites, where manual moisture testing is essential for consistent mix quality.
Authoritative ACI, ASTM, and PCA references for concrete mix design and gravel ratio selection in the USA
ACI 211.1 "Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete" is the primary US standard for concrete mix design — covering water-cement ratio selection, coarse aggregate (gravel) fraction tables by aggregate size, cement content calculations, fine aggregate proportioning, admixture adjustments, and the complete ACI absolute volume method for calculating all material quantities per cubic yard of concrete for any specified compressive strength.
View ACI 211.1ASTM C33 "Standard Specification for Concrete Aggregates" defines the gradation, cleanliness, durability, and physical property requirements for fine aggregate (sand) and coarse aggregate (gravel and crushed stone) used in concrete throughout the USA — including the standard #67 (3/4-in), #57 (1-in), and #89 (3/8-in) gravel size designations referenced in all US concrete mix designs, ready-mix specifications, and ACI 211.1 mix design tables.
View ASTM C33The Portland Cement Association (PCA) "Design and Control of Concrete Mixtures" (EB001) is the most widely used practical reference for concrete mix design in the USA — covering cement types per ASTM C150, aggregate selection per ASTM C33, water-cement ratio tables, gravel ratio proportioning, admixture selection, air entrainment requirements by climate zone, and complete worked examples of ACI 211.1 mix design calculations for all residential, commercial, and infrastructure applications.
View PCA Guide