Concrete Calculator
Use this professional concrete calculator to instantly determine total volume in cubic yards, cubic feet, and cubic meters. Automatically estimate required bags of standard pre-mixed concrete based on custom project dimensions and a safety waste margin.
1 · Project Specifications
Dimensions
Length of the area to pour.
Width of the area to pour.
Thickness or depth of the concrete pour.
Options
Adds extra concrete (10% recommended) to cover subgrade unevenness and spillage.
2 · Material Estimates
Estimation Results
Enter your measurements and click Calculate to see your estimate.
Detailed Project Guide & Calculation Methodology
Calculation Formulas & Methodology
Volume Formula
Volume = Length × Width × DepthComputes the raw three-dimensional space of the project.
Imperial Formula
Yards = (Length (ft) × Width (ft) × (Depth (in) / 12)) / 27Converts depth from inches to feet, calculates cubic feet, and divides by 27 to find cubic yards.
Metric Formula
Meters³ = Length (m) × Width (m) × (Depth (cm) / 100)Converts depth from centimeters to meters, and calculates the volume in cubic meters.
Bag Calculation Formula
Bags = Volume (cu ft) / Bag YieldDivides total volume by bag yields: 0.60 cu ft (80lb), 0.45 cu ft (60lb), or 0.30 cu ft (40lb).
How It Works
- 1Select your preferred units for Length, Width, and Depth (Feet/Inches or Meters/Centimeters).
- 2Input the dimensions of your pour area.
- 3Adjust the waste allowance percentage (10% is recommended for standard jobs).
- 4Click Calculate to see immediate volume results and bag counts.
Frequently Asked Questions
To calculate concrete, multiply the length by the width to get square footage, then multiply by the depth (thickness) in feet to get cubic feet. Divide cubic feet by 27 to get cubic yards.
There are 45 bags of 80 lb concrete mix in one cubic yard. Each 80 lb bag yields approximately 0.60 cubic feet of concrete, and a cubic yard is 27 cubic feet.
Yes. We recommend adding a 10% waste allowance to account for spillage, slab variations, and uneven subgrades. This calculator includes a waste slider to customize this allowance.
For standard walkways and patios, a 4-inch thickness is standard. For driveways and heavy-duty slabs, a minimum of 5 to 6 inches is recommended.
A cubic yard is a volume measurement representing a cube that is 3 feet long, 3 feet wide, and 3 feet deep (totaling 27 cubic feet). It weighs approximately 4,000 lbs (2 short tons).
✓ Pro Tips
- •Always add a 10% safety margin (waste allowance) to ensure you don't run short.
- •For projects over 1 cubic yard, consider ordering ready-mix delivery instead of mixing bags by hand — mixing 45 bags of 80 lb concrete takes significant effort.
- •Keep concrete damp for at least 3 to 5 days after pouring to help it cure to full strength.
⚠ Common Mistakes
- •Using nominal lumber sizes for depth (e.g. assuming a 2x4 form is exactly 4 inches deep; a 2x4 is actually 3.5 inches deep).
- •Forgetting to account for ground settling and slab thickness variations.
- •Underestimating waste and running out of concrete mid-pour, which ruins the finish.
Share Your Estimate
Related Calculators
Calculate cubic yards, tons, and bags of gravel required for driveways, paths, or utility foundations.
landscapingEstimate organic loam, soil, or compost replacement volumes for raised beds, yards, and grading.
landscapingDetermine bulk cubic yards or standard retail bags of bark mulch for gardens and flower beds.
landscapingPlanning Guides & Advice
- How Much Concrete Do I Need? Slabs & Footings Guide
Learn how to calculate concrete volume in cubic yards or bag count for driveways, patios, and fence posts.
- Concrete Bags Per Cubic Yard: 40lb, 60lb & 80lb Guide
Learn exactly how many concrete bags you need per cubic yard for common bag sizes. Includes reference tables, yield conversions, and ordering tips.
- Concrete Patio Thickness Guide: Right Depth for Every Use
Learn the correct concrete slab thickness for patios, driveways, sidewalks, pool decks, and heavy-vehicle pads.
DIY Estimation Checklist
- •Measure lengths and heights twice for accuracy.
- •Check product labels for actual coverage rates.
- •Order materials with a 10% buffer for cuts and waste.
- •Account for doors, windows, and obstacles.
- •Compare quotes from at least two suppliers.