Concrete Calculator

Calculate the volume of concrete needed for slabs, footings, columns, walls, and stairs

Concrete Volume Calculator

Select a shape below and enter dimensions to calculate the amount of concrete needed for your project.

Select Shape:

Slab
Slabs, Square Footings, or Walls
Round Footing
Hole, Column, or Round Footings
Circular Slab
Circular Slab or Tube
Curb
Curb and Gutter Barrier
Stairs
Stairs

Dimensions

Pricing (Optional)

Average price is $150 per cubic yard

Concrete Volume Required

Cubic Yards
0.00
Cubic Feet
0.00
Cubic Meters
0.00

Concrete Bags Needed

80 lb Bags
0
0.6 cu ft per bag
60 lb Bags
0
0.45 cu ft per bag

Estimated Cost

Total Cost
$0.00

About Concrete Calculator

Calculate the amount of concrete needed for various construction projects including slabs, footings, columns, walls, curbs, and stairs. This calculator helps you estimate the volume of concrete required in cubic yards, cubic feet, and cubic meters, plus the number of bags needed.

Concrete Types and Uses

Shape Type Common Uses Typical Dimensions
Slabs Driveways, patios, floors, sidewalks 4-6 inches thick
Square Footings Building foundations, deck posts 12-24 inches deep
Round Footings Fence posts, deck columns, light poles 8-12 inches diameter
Walls Retaining walls, foundation walls 6-12 inches thick
Curbs & Gutters Street curbing, drainage systems 6 inches high, 6 inches wide
Stairs Outdoor steps, entrance steps 7 inch rise, 11 inch run

Concrete Measurement Conversions

Volume Conversions:
1 Cubic Yard = 27 Cubic Feet
1 Cubic Yard = 0.764555 Cubic Meters
1 Cubic Meter = 1.30795 Cubic Yards
1 Cubic Meter = 35.3147 Cubic Feet
Bag Sizes:
80 lb bag = 0.6 cubic feet
60 lb bag = 0.45 cubic feet
40 lb bag = 0.3 cubic feet

Example: A 10x10 ft slab, 4 inches thick needs 1.23 cubic yards or approximately 56 bags (80 lb)

How to Calculate Concrete Volume

Slab, Square Footing, or Wall Formula:
Volume (cubic feet) = Length × Width × Thickness
Note: Convert thickness from inches to feet by dividing by 12

Example:
Slab: 10 ft × 10 ft × 4 inches
= 10 × 10 × (4/12)
= 33.33 cubic feet
= 1.23 cubic yards
Round Column or Footing Formula:
Volume (cubic feet) = π × r² × Height
Where r = radius (diameter ÷ 2)

Example:
Column: 12 inches diameter, 8 feet high
Radius = 12 ÷ 2 = 6 inches = 0.5 feet
= 3.14159 × (0.5)² × 8
= 6.28 cubic feet
= 0.23 cubic yards
Circular Slab Formula:
Volume (cubic feet) = π × r² × Thickness

Example:
Circular patio: 15 feet diameter, 4 inches thick
Radius = 15 ÷ 2 = 7.5 feet
= 3.14159 × (7.5)² × (4/12)
= 58.9 cubic feet
= 2.18 cubic yards
Stairs Formula:
Volume = (Number of Steps × Rise × Run × Width) ÷ 2

Example:
5 steps, 3 feet wide, 7 inch rise, 11 inch run
Total rise = 5 × 7 = 35 inches = 2.92 feet
Total run = 5 × 11 = 55 inches = 4.58 feet
= (2.92 × 4.58 × 3) ÷ 2
= 20.06 cubic feet
= 0.74 cubic yards

Concrete Thickness Guidelines

Application Recommended Thickness Notes
Sidewalks 4 inches Standard for foot traffic
Patios 4 inches Can be 3 inches for light use
Residential Driveways 4-6 inches 6 inches for heavy vehicles
Commercial Driveways 6-8 inches Heavy duty applications
Garage Floors 4-6 inches Depends on vehicle weight
Foundation Walls 8-10 inches Varies by building code
Basement Floors 4 inches Over compacted gravel base

Concrete Ordering Tips

  • Order Extra: Always order 5-10% more concrete than calculated to account for spillage, uneven ground, and over-excavation
  • Minimum Orders: Most ready-mix companies have a minimum order of 1 cubic yard
  • Delivery Time: Plan for concrete to arrive when you're ready - it begins to set within 90 minutes
  • Access: Ensure the concrete truck can access your site (within 150 feet of pour location)
  • Weather: Avoid pouring in extreme temperatures (below 40°F or above 90°F)
  • Base Preparation: Ensure proper base preparation with compacted gravel

Concrete Bag vs Ready-Mix

Method Best For Advantages Disadvantages
Bagged Concrete Small projects under 1 cubic yard No delivery fees, work at your pace, no minimums Labor intensive, more expensive per yard, time consuming
Ready-Mix Projects over 1 cubic yard Faster, consistent quality, less labor, cost effective for large projects Delivery fees, minimum orders, time pressure, truck access needed

Common Concrete Mixes

  • Standard Mix (3000 PSI): General purpose for slabs, sidewalks, and driveways
  • High-Strength Mix (4000 PSI): For foundations, columns, and heavy load areas
  • Fast-Setting Mix: Sets in 20-40 minutes, good for posts and repairs
  • Crack-Resistant Mix: Contains fibers to reduce shrinkage cracks
  • Air-Entrained Mix: Better freeze-thaw resistance for cold climates

Cost Factors

  • Ready-Mix Concrete: $125-$150 per cubic yard (average)
  • High-Strength Concrete: $150-$200 per cubic yard
  • Colored Concrete: Add $100-$200 per cubic yard
  • Fiber-Reinforced: Add $40-$100 per cubic yard
  • Delivery Fees: $60-$200 depending on distance
  • Short Load Fee: $50-$100 for orders under minimum
  • 80 lb Bags: $4-$8 per bag (0.6 cubic feet)
  • 60 lb Bags: $3-$6 per bag (0.45 cubic feet)

Important Considerations

  • Reinforcement: Most slabs require wire mesh or rebar for added strength
  • Subbase: Proper compacted gravel base (4-6 inches) is essential
  • Forms: Build sturdy forms to contain concrete during pour
  • Slope: Ensure proper drainage slope (1/4 inch per foot minimum)
  • Control Joints: Cut control joints to prevent random cracking
  • Curing: Keep concrete moist for 7 days for proper strength development
  • Permits: Check local building codes and permit requirements

Safety Tips

  • Wear protective equipment: gloves, safety glasses, and boots
  • Concrete is caustic - avoid skin contact and wash immediately if exposed
  • Have helpers available - concrete work is physically demanding
  • Plan for rapid work - concrete begins setting quickly
  • Ensure proper ventilation when working in enclosed spaces
  • Keep children and pets away from work area

Frequently Asked Questions

Q: How much does a cubic yard of concrete weigh?
A: Approximately 4,000 pounds (2 tons) when wet.
Q: How long does concrete take to cure?
A: Concrete reaches about 70% strength in 7 days and full strength in 28 days, but you can walk on it after 24-48 hours.
Q: Can I pour concrete in the rain?
A: Light rain after the concrete has started to set is okay, but heavy rain or rain during pouring can weaken the concrete. Cover with plastic if rain is expected.
Q: Do I need permits for a concrete project?
A: It depends on your location and project size. Check with your local building department. Most areas require permits for driveways, patios over a certain size, and any structural concrete.
Q: Should I use bags or ready-mix?
A: For projects under 1 cubic yard (like a small walkway or a few post holes), bags are convenient. For anything larger, ready-mix is more cost-effective and ensures better consistency.