Concrete Calculator — Cubic Yards, Bags & Cost

How Much Concrete Do I Need?

Most residential concrete projects need between 1 and 10 cubic yards. The exact amount depends on three things: the dimensions of what you're pouring, the depth or thickness, and whether you're pouring a slab, footing, column, or post hole.

The basic formula for slab-style pours is:

Concrete needed (cubic yards) = (Length × Width × Depth) ÷ 27

All measurements should be in feet, with depth converted from inches to feet. Divide cubic feet by 27 to get cubic yards.

Quick estimates for common slab projects:

• 10 ft × 10 ft × 4 inches deep — 1.23 cubic yards
• 12 ft × 12 ft × 4 inches deep — 1.78 cubic yards
• 20 ft × 20 ft × 4 inches deep — 4.94 cubic yards
• 30 ft × 30 ft × 4 inches deep — 11.11 cubic yards
• 40 ft × 60 ft × 6 inches deep — 44.44 cubic yards (would need a commercial pour)

Always order 5 to 10% extra to account for spillage, uneven ground, and form deflection. Concrete that doesn't get used is far cheaper than running short mid-pour and ruining the job.

The calculator above handles all standard project shapes. For specialty pours (cylinders, post holes, columns), see the dedicated sections below.

How Much Does Concrete Cost in 2026?

Concrete pricing varies significantly by region, project complexity, and whether you're buying ready-mix delivered or bagged concrete from a hardware store. Here are realistic 2026 ranges for budget planning.

Ready-mix concrete pricing (delivered by truck):

• Standard 3,000 PSI mix — $130 to $170 per cubic yard
• 4,000 PSI mix (driveways, foundations) — $150 to $200 per cubic yard
• 5,000 PSI mix (heavy load applications) — $170 to $230 per cubic yard
• Most suppliers have a 1 to 2 yard minimum
• Short-load fees apply under 5 yards: $50 to $150 extra

Total delivered ready-mix cost typically runs $150 to $250 per cubic yard once you factor in delivery and short-load fees.

Bagged concrete pricing (Quikrete, Sakrete, similar):

• 60-lb bag — $4 to $7 per bag
• 80-lb bag — $5 to $8 per bag
• 90-lb bag — $7 to $10 per bag

Common cost estimates by yardage:

• 1 yard of concrete delivered — $150 to $250
• 2 yards delivered — $300 to $400 (still likely to incur short-load fee)
• 4 yards delivered — $600 to $1,000
• 8 yards delivered — $1,040 to $1,600 (no short-load fee at this volume)
• 9 yards delivered — $1,170 to $1,800

When ready-mix beats bagged concrete:

The break-even is around 0.5 to 1 cubic yard. Below that (small footings, post holes, fence posts), bagged is cheaper. Above 1 yard, ready-mix delivery wins on cost AND quality.

A typical 10×10 slab (1.23 cubic yards) is right at the break-even — calculate both options.

How Many Bags of Concrete in a Cubic Yard?

This is the most-asked concrete question because most homeowners think in bags, not yards. The answer depends on bag size.

Bags per cubic yard by bag size:

• 40-lb bag — 90 bags per cubic yard
• 60-lb bag — 60 bags per cubic yard
• 80-lb bag — 45 bags per cubic yard
• 90-lb bag — 40 bags per cubic yard

For common project sizes, here's how many bags you need:

For a 10×10 slab at 4 inches deep (1.23 cubic yards):

• 56 bags of 80-lb concrete
• 74 bags of 60-lb concrete
• 111 bags of 40-lb concrete

For a 10×20 slab at 4 inches deep (2.47 cubic yards):

• 111 bags of 80-lb concrete
• 148 bags of 60-lb concrete

At these volumes (1+ cubic yards), bagged concrete is significantly more expensive than ready-mix delivery, but homeowners still use bagged for small pours where mixing capacity matters more than cost.

How many bags fit on a pallet:

Standard concrete pallets hold:

• 80-lb bags — 42 bags per pallet (3,360 lb total)
• 60-lb bags — 56 bags per pallet (3,360 lb total)
• 40-lb bags — 80 bags per pallet (3,200 lb total)

Most home centers sell concrete in pallet quantities at a small discount over loose bags.

How Many Bags for a 10×10 Slab?

A 10 ft × 10 ft slab at standard 4-inch thickness needs 1.23 cubic yards of concrete. In bag form:

• 56 bags of 80-lb concrete ($280 to $448)
• 74 bags of 60-lb concrete ($296 to $518)
• Or 1.5 cubic yards of ready-mix delivered ($225 to $375 with potential short-load fee)

For a 10×10 slab, ready-mix is usually cheaper after factoring in mixing labor and consistency benefits.

Common slab sizes and concrete needs:

8 ft × 8 ft — 0.79 cubic yards or 36 bags of 80-lb concrete
10 ft × 10 ft — 1.23 cubic yards or 56 bags
10 ft × 12 ft — 1.48 cubic yards or 67 bags
12 ft × 12 ft — 1.78 cubic yards or 80 bags
12 ft × 16 ft — 2.37 cubic yards or 107 bags
16 ft × 20 ft — 3.95 cubic yards or 178 bags
20 ft × 20 ft — 4.94 cubic yards or 222 bags

For 6-inch slabs (driveways, garages), multiply the cubic yards by 1.5.

Concrete Slab Cost Calculator

Concrete slab costs combine material, labor, and finishing. Here's what to expect for a finished installed slab in 2026.

Total installed concrete slab costs:

• 10×10 slab (basic patio) — $1,500 to $2,500
• 10×20 slab (small driveway pad) — $2,800 to $4,500
• 12×24 slab (one-car garage floor) — $4,000 to $6,500
• 20×20 slab (two-car garage floor) — $6,000 to $9,500
• 24×30 slab (large garage or shop) — $9,000 to $14,000

Cost breakdown for a typical 10×10 slab:

• Concrete material — $200 to $400
• Forming and rebar — $200 to $400
• Labor — $800 to $1,400
• Finishing (broom finish standard) — $100 to $200
• Cleanup and disposal — $50 to $100

What changes the cost:

• Thickness: 6-inch slabs cost 25-35% more than 4-inch
• Reinforcement: Wire mesh adds $50-150; rebar adds $200-500
• Finish type: Stamped or stained concrete adds $4-12 per sq ft
• Site prep: Removing old concrete or grading adds $500-2,000
• Access: Difficult-access sites (no truck access) add $300-800

For accurate estimates, get 3 quotes from local concrete contractors. Online calculator estimates work for budgeting; final pricing varies 20-30% by region.

Concrete Pad Cost Calculator

Concrete pads (smaller standalone slabs for AC units, sheds, generators, hot tubs) follow different cost patterns than large slabs because they're a fixed minimum charge regardless of small size.

Common concrete pad sizes and installed costs:

• AC unit pad (3×3 to 4×4) — $300 to $500
• Generator pad (4×4 to 5×5) — $400 to $700
• Shed pad (8×8 to 10×12) — $800 to $1,800
• Hot tub pad (8×8 with reinforcement) — $1,000 to $2,200
• Equipment pad (5×8) — $500 to $900

Why small pads cost more per square foot:

A 3×3 AC pad has only 1.5 cubic feet of concrete — under $30 in material — but contractors charge $300+ because the labor (forming, mixing, leveling, finishing) takes nearly as long as a slightly larger pour. Most contractors have a $300-500 minimum job fee.

DIY pad costs: A 4×4 pad can be DIY'd for $50-100 in materials (8 bags of 80-lb concrete, $20 in form lumber, rebar) versus $400-700 hired. The math favors DIY for pads under 6×6 if you have basic concrete skills.

Concrete Sidewalk Cost Calculator

Sidewalk cost combines linear footage with width. Standard residential sidewalks run 3 to 4 feet wide.

Concrete sidewalk pricing per linear foot:

• 3-ft wide × 4-inch thick — $20 to $35 per linear foot
• 4-ft wide × 4-inch thick — $25 to $45 per linear foot
• 5-ft wide × 4-inch thick — $32 to $55 per linear foot

For typical residential sidewalk projects:

• 20-ft sidewalk (driveway to door) — $400 to $900
• 50-ft sidewalk (full front yard run) — $1,000 to $2,250
• 100-ft sidewalk (long path to backyard) — $2,000 to $4,500

What's included in sidewalk pricing:

• Excavation and grading
• Form setup
• 4-inch base of compacted gravel
• Wire mesh reinforcement
• 4-inch concrete pour
• Broom finish
• Form removal

What adds cost:

• Demolition of existing sidewalk: $4-10 per sq ft
• Stamped or decorative finish: $8-18 per sq ft additional
• Curves rather than straight runs: 15-25% premium
• ADA-compliant slope and ramps: $200-500 additional per ramp

For accurate estimates, calculate your linear footage × cost-per-foot, then add 10-15% for site-specific complications.

Concrete Foundation Calculator

Foundations require more concrete than slabs because they include footings (the wider base below the wall) plus the foundation wall itself.

For a typical residential foundation, calculate two volumes:

1. Footing volume: Width × Depth × Linear feet of perimeter × ÷ 27 = cubic yards

Standard footings are 16-24 inches wide × 8-12 inches deep, depending on local code and soil conditions.

2. Wall volume: Wall thickness × Wall height × Linear feet of perimeter ÷ 27 = cubic yards

Standard residential foundation walls are 8-10 inches thick × 8 feet tall.

Foundation concrete needs by home size:

• 1,500 sq ft home foundation — 18 to 25 cubic yards
• 2,000 sq ft home foundation — 22 to 32 cubic yards
• 2,500 sq ft home foundation — 28 to 38 cubic yards
• 3,000 sq ft home foundation — 32 to 45 cubic yards

These are general estimates. Actual foundation concrete depends heavily on whether you have a basement (more concrete) or crawl space (less), local frost depth requirements, and foundation type (poured vs. block vs. ICF).

Foundation cost in 2026:

• Slab-on-grade foundation — $5,000 to $15,000 for typical home
• Crawl space foundation — $8,000 to $20,000
• Basement foundation (poured) — $20,000 to $50,000+

For specific foundation calculations, work directly with a structural engineer or your concrete contractor. Online calculators give ballpark figures only — foundation work is too critical to estimate from a generic tool.

Concrete Cylinder and Post Hole Calculator

Cylinder-shaped concrete pours (post holes, deck footings, sonotube columns) calculate differently from rectangular slabs because of the circular shape.

The cylinder formula:

Concrete needed (cubic feet) = π × radius² × height

Where:

• π = 3.14159
• radius = half the cylinder's diameter (in feet)
• height = depth of the hole or column (in feet)

Then divide cubic feet by 27 for cubic yards.

Common post hole and footing concrete needs:

For a single 12-inch diameter × 36-inch deep post hole:

• Volume: π × 0.5² × 3 = 2.36 cubic feet
• Bags needed: 4 bags of 60-lb concrete (or 3 bags of 80-lb)

For a 10-inch diameter × 48-inch deep deck footing:

• Volume: π × 0.42² × 4 = 2.20 cubic feet
• Bags needed: 3-4 bags of 60-lb concrete

Quick reference for common post hole sizes:

8-inch diameter × 24 inches deep — 0.70 cubic feet or 1.5 bags of 60-lb concrete
8-inch diameter × 36 inches deep — 1.05 cubic feet or 2 bags
10-inch diameter × 36 inches deep — 1.64 cubic feet or 3 bags
10-inch diameter × 48 inches deep — 2.18 cubic feet or 4 bags
12-inch diameter × 36 inches deep — 2.36 cubic feet or 4 bags
12-inch diameter × 48 inches deep — 3.14 cubic feet or 5 bags

For multiple post holes, multiply the per-hole bags by total holes, then add 10% extra. A typical fence with 20 posts at 12-inch × 36-inch deep needs about 88 bags of 60-lb concrete.

Concrete Mix Ratios — 1:2:4 and Other Standards

Concrete is a mix of cement, sand (fine aggregate), and gravel (coarse aggregate). Different ratios produce different strengths.

Standard concrete mix ratios:

• 1:2:4 mix (most common, ~3,000 PSI) — 1 part cement, 2 parts sand, 4 parts gravel
• 1:1.5:3 mix (stronger, ~4,000 PSI) — for driveways and reinforced slabs
• 1:3:6 mix (lower strength, ~2,000 PSI) — for non-structural fills only

1:2:4 mix calculator (for 1 cubic yard):

To make 1 cubic yard of 1:2:4 concrete from raw ingredients:

• Cement: 5.5 to 6 bags of Portland cement (94-lb bags)
• Sand: 14 to 16 cubic feet of sand
• Gravel: 28 to 32 cubic feet of gravel
• Water: 30 to 36 gallons

This produces approximately 27 cubic feet (1 cubic yard) of finished concrete.

Why bagged concrete is easier: Pre-mixed bags (Quikrete, Sakrete, etc.) handle the ratio for you. They're already 1:2:4 inside the bag — you just add water. Use bagged for any project under 1 cubic yard. Custom mixing from raw ingredients only makes sense at large project scales.

Strength testing: If you're pouring something structural (footings, foundation walls), specify the PSI directly to your ready-mix supplier rather than calculating ratios. Standard residential applications use 3,000 PSI; driveways and garages use 4,000 PSI.

Step-by-Step — How to Calculate Yards of Concrete

If you want to do the math without the calculator, here's the exact process for a slab pour.

Step 1: Measure the area

For rectangular slabs, measure length and width in feet. For irregular shapes, break the area into rectangles, calculate each separately, and add them together. For circles, use π × radius².

Step 2: Decide on thickness

Common slab thicknesses:

• Sidewalks and patios — 4 inches
• Driveways and garage floors — 6 inches
• Heavy-load slabs (workshops, vehicle pads) — 6 to 8 inches
• Footings — 8 to 12 inches

Step 3: Convert thickness from inches to feet

Divide depth in inches by 12:

• 4 inches = 0.33 ft
• 6 inches = 0.5 ft
• 8 inches = 0.67 ft
• 12 inches = 1.0 ft

Step 4: Calculate cubic feet

Length × Width × Depth (all in feet) = Cubic feet

Example: 12 ft × 16 ft × 0.5 ft = 96 cubic feet

Step 5: Convert cubic feet to cubic yards

Divide cubic feet by 27.

Example: 96 ÷ 27 = 3.56 cubic yards

Step 6: Add 5-10% for waste

Round up. The example becomes 4 cubic yards ordered.

Step 7: Convert to bags (if buying bagged)

Divide cubic feet by bag yield:

• 80-lb bag yields 0.6 cubic feet — 96 ÷ 0.6 = 160 bags
• 60-lb bag yields 0.45 cubic feet — 96 ÷ 0.45 = 213 bags

For 4 cubic yards, ready-mix delivery is the right call. The calculator above does all this in seconds, but understanding the math helps you sanity-check supplier quotes and plan multi-stage projects.

Concrete Coverage Quick-Reference Tables

For fast estimating, these tables cover the most common concrete projects.

1 cubic yard of concrete covers:

• 4 inches thick — 81 sq ft
• 5 inches thick — 65 sq ft
• 6 inches thick — 54 sq ft
• 8 inches thick — 40 sq ft
• 12 inches thick — 27 sq ft

Yards needed for common projects (4-inch thickness):

• 100 sq ft slab — 1.23 yards
• 200 sq ft slab — 2.47 yards
• 300 sq ft slab — 3.70 yards
• 500 sq ft slab — 6.17 yards
• 1,000 sq ft slab — 12.35 yards

Yards needed for common projects (6-inch thickness):

• 100 sq ft slab — 1.85 yards
• 200 sq ft slab — 3.70 yards
• 300 sq ft slab — 5.56 yards
• 500 sq ft slab — 9.26 yards
• 1,000 sq ft slab — 18.52 yards

These figures assume flat, level pours. Actual concrete needed runs 5-10% higher to account for waste, uneven base, and form deflection.