Concrete Calculator: Bags & Yards Estimator

Use this concrete calculator to estimate how much concrete you need for common shapes and projects. Get results in cubic yards (yardage for ready-mix orders), cubic feet, and cubic meters, plus optional estimates for bags of concrete and concrete weight. This master hub focuses on general volume math and conversions—then links you to specialized calculators when you need deeper guidance.

Concrete yardage is the amount of concrete expressed in cubic yards (yd³), which is the most common unit used by ready-mix suppliers. One cubic yard is the volume of a cube that measures 3 feet × 3 feet × 3 feet, which equals 27 cubic feet. If you calculate a project in cubic feet, you can convert to cubic yards by dividing by 27.

Step 1 (convert to feet): Convert all inputs to feet before calculating volume.

• Length/Width: if using meters → ft = m × 3.28084
• Depth: if inches → ft = in ÷ 12, if centimeters → ft = cm ÷ 30.48, if millimeters → ft = mm ÷ 304.8

Step 2 (cubic feet): ft³ = Length(ft) × Width(ft) × Depth(ft)

Step 3 (cubic yards): yd³ = ft³ ÷ 27

Optional (cubic meters): m³ = ft³ ÷ 35.3147

If your project is round (for example, a circular pad), you can estimate volume using the circle formula. For posts and structural footings, use the dedicated footing calculator for best guidance.

Circle volume (cubic feet): ft³ = π × r² × Depth(ft)

• π ≈ 3.1416
• r = radius in feet (radius = diameter ÷ 2)
• Depth(ft) = thickness converted to feet

Then convert to cubic yards: yd³ = ft³ ÷ 27.

Example: A 10 ft × 12 ft area at 4 inches thick.

• Depth in feet = 4 ÷ 12 = 0.3333 ft
• Cubic feet = 10 × 12 × 0.3333 ≈ 40.00 ft³
• Cubic yards = 40.00 ÷ 27 ≈ 1.48 yd³

Optional waste factor: Add 10% → 1.48 × 1.10 ≈ 1.63 yd³.

These conversions help you switch between ordering units and calculator outputs:

• 1 yd³ = 27 ft³
• yd³ = ft³ ÷ 27
• ft³ = yd³ × 27
• 1 m³ = 35.3147 ft³
• m³ = ft³ ÷ 35.3147
• 1 yd³ ≈ 0.7646 m³
• 1 m³ ≈ 1.308 yd³

If you're mixing concrete yourself, estimate bags of concrete using the total volume in cubic feet and the bag yield. Bag yields vary by product, but common planning yields are:

• 40 lb bag: ~0.30 ft³
• 60 lb bag: ~0.45 ft³
• 80 lb bag: ~0.60 ft³

Bag formula: Bags = Total ft³ ÷ Bag Yield (ft³ per bag)

Tip: For the most accurate bag count, use the yield printed on your bag (especially when using brands like Quikrete or Sakrete).

Concrete is heavy, so it helps to estimate weight for hauling, staging, and access planning. Normal-weight concrete is commonly estimated around 145–150 lb per cubic foot (varies by mix and aggregate).

Planning weight formulas:

• Weight (lb) = Volume (ft³) × 150
• Weight (lb) = Volume (yd³) × 4,050 (since 1 yd³ = 27 ft³)

Example: 1.63 yd³ × 4,050 ≈ 6,602 lb.

Ready-mix suppliers typically sell concrete by the cubic yard (yd³). If your estimate is large or you need consistent results quickly, ready-mix can be more practical than mixing many bags.

Important: Minimum loads and delivery policies vary by supplier. If you're planning a slab pour, reinforcement, finish timing, or other slab-specific details, use the slab calculator: /concrete-slab-calculator.

• Walkways & pads: general flatwork volume estimates (use slab calculator for slab-specific guidance)
• Patios: yardage planning and waste factor
• Repairs: bag count estimates for small patch jobs
• General construction: quick conversions between ft³, yd³, and m³

• Add a buffer: Many projects benefit from ordering extra (often 5–15%) for waste, uneven subgrade, and spillage.
• Confirm thickness: A small change in depth can significantly change yardage.
• Check access: If ordering ready-mix, confirm truck access and chute reach.
• Use bag yields: For Quikrete/Sakrete or any brand, use the yield printed on the bag for best accuracy.