Concrete Calculator
Calculate exactly how much concrete you need for any project. Get instant volume calculations, bag counts, and cost estimates for slabs, driveways, footings, and more.
Dimensions
Pro Tips
- →Measure to the nearest inch for accuracy
- →Add 5-10% extra for waste and spillage
- →Consider ground conditions when ordering
Includes 10% waste factor
Cost Estimate
Estimated material costs for your project
Recommendation: Ready-Mix Concrete
For projects over 1 cubic yard, ready-mix is typically more economical and easier to work with.
123 bags × 80lb
2.72 cubic yards + delivery
200 sq ft × $3.00–$8.00/sq ft
Prices vary by location and time. Contact local suppliers for accurate quotes.
Shape Types
Slabs, cylinders, curbs, stairs, columns, walls, footings, circles, and tubes
Always Free
No signup required. Calculate unlimited projects with full features
Units
Imperial and metric support for projects anywhere
How to Calculate Concrete
Concrete volume is measured in cubic yards. Use this formula for any rectangular slab, pad, or footing.
Convert thickness from inches to feet first by dividing by 12. For example, a 4-inch slab = 4 ÷ 12 = 0.333 ft.
| Slab Size | Cubic Yards | 80-lb Bags | 60-lb Bags |
|---|---|---|---|
| 10 × 10 ft at 4 in thick | 0.62 | 28 | 37 |
| 12 × 12 ft at 4 in thick | 0.89 | 41 | 54 |
| 16 × 16 ft at 4 in thick | 1.58 | 72 | 96 |
| 20 × 20 ft at 4 in thick | 2.47 | 113 | 150 |
| 20 × 40 ft at 4 in thick | 4.94 | 224 | 299 |
Bagged vs. Ready-Mix
For projects under 1 cubic yard, bagged concrete is the practical choice — it's available at any hardware store and requires no truck coordination. Once you cross the 1-yard mark, ordering ready-mix from a plant is faster, cheaper per unit, and results in a more consistent mix.
Standard Slab Thickness
Residential patios and sidewalks are typically poured at 4 inches thick. Driveways that carry vehicle weight should be 5–6 inches. Structural slabs, garage floors, and any slab with heavy load requirements may call for 6 inches or more with rebar reinforcement.
The 10% Waste Rule
Always order 10% more concrete than your calculated volume. Subgrade irregularities, spillage, and slight over-excavation add up quickly. Running short on a pour is expensive — the truck has to return, and a cold joint in a finished slab is difficult to repair cleanly.
Project Calculators
Pre-configured calculators for specific project types with tailored defaults and tips.
Basement Floor Cost Calculator
Estimate your concrete basement floor costs with our free calculator.
Column Calculator
Calculate concrete needed for columns and pillars with our free tool.
Slab Cost Calculator
Estimate your concrete slab costs with our free calculator.
Curb Calculator
Building concrete curbs? Calculate exactly how much concrete you need with our free tool.
Deck Footing Calculator
Building a deck? Calculate concrete needed for deck footings with our free tool.
Driveway Calculator
Planning a driveway? Calculate exactly how much concrete you need with our free tool.
Driveway Cost Calculator
Estimate your driveway costs with our free calculator.
Footing Calculator
Calculate concrete needed for footings with our free tool.
Foundation Calculator
Planning a foundation? Calculate concrete needs for foundation walls and footings with our free tool.
Garage Floor Calculator
Planning a garage floor? Calculate exactly how much concrete you need with our free tool.
Garage Floor Cost Calculator
Estimate your concrete garage floor costs with our free calculator.
Patio Calculator
Planning a patio? Use our free calculator to determine how much concrete you need.
Patio Cost Calculator
Estimate your patio costs with our free calculator.
Pier Footing Calculator
Building pier footings? Calculate concrete needs with our free tool.
Pool Deck Cost Calculator
Estimate your concrete pool deck costs with our free calculator.
Post Hole Calculator
Setting posts? Calculate exactly how much concrete you need for post holes with our free tool.
Shed Base Cost Calculator
Estimate your concrete shed base costs with our free calculator.
Shed Foundation Calculator
Building a shed foundation? Calculate exactly how much concrete you need with our free tool.
Sidewalk Calculator
Building a sidewalk? Calculate exactly how much concrete you need with our free tool.
Slab Calculator
Calculate concrete needed for any slab project.
Steps Calculator
Building concrete steps? Calculate exactly how much concrete you need with our free tool.
Steps Cost Calculator
Estimate your concrete steps cost with our free calculator.
Walkway Calculator
Planning a walkway or garden path? Calculate your concrete needs with our free tool.
DIY vs Pro Finishing Tool Calculator
Concrete finishing is one of the few construction tasks where mistakes are permanent and expensive.
Finish Type Cost Estimator Calculator
Different concrete finishes vary dramatically in cost — from $4/sq ft for a basic broom finish to $18+/sq ft for premium stamped patterns.
Finishing Timing Estimator Calculator
Timing is the single biggest factor in concrete finishing quality.
Parking Garage Spec Calculator
Generate preliminary concrete specifications for parking structures by garage type, climate exposure class, and vehicle loading.
Sonotube Calculator
Using sonotubes? Calculate exactly how much concrete you need with our free tool.
Stamped Cost Calculator
Estimate your stamped concrete costs with our free calculator.
Expert Guides
Learn the right way to calculate, pour, and finish concrete projects.
Complete Guide to Concrete for DIY Projects
Concrete work is absolutely achievable for homeowners willing to plan carefully and respect the material's demands. This guide covers everything you need to successfully complete a concrete project—from understanding what concrete actually is, to calculating quantities, to finishing techniques that produce professional results.
How to Calculate Concrete (Step-by-Step Guide)
The formula for calculating concrete is Length × Width × Thickness (all in feet) ÷ 27 = cubic yards. For a 12×10 foot patio at 4 inches thick, that's 12 × 10 × 0.33 ÷ 27 = 1.47 cubic yards.
How to Pour Concrete (Complete DIY Guide)
Pouring concrete is the moment everything comes together—or falls apart. The actual pour is surprisingly fast (30-90 minutes for most residential projects), but it's unforgiving. Once concrete starts setting, you can't pause, restart, or fix major mistakes. Success depends entirely on preparation and coordination.
How Much Does Concrete Cost Per Yard? (2026 Prices)
Ready-mix concrete costs $125-175 per cubic yard delivered in 2026, but that base price rarely tells the whole story. Between minimum order requirements, short-load fees, and Saturday delivery surcharges, your actual cost can vary significantly from the quoted per-yard rate.
How Many Bags of Concrete Do I Need? (Bag Calculator)
One cubic yard of concrete equals 45 bags of 80-lb mix, 60 bags of 60-lb mix, or 90 bags of 40-lb mix. For a 10×10 patio at 4 inches thick, you need approximately 55 bags of 80-lb concrete.
Learning Resources
Expand your concrete knowledge with our comprehensive glossary and guides.
Concrete Glossary
Plain-English definitions of 20+ concrete terms. From "curing" to "compressive strength," understand the vocabulary of concrete work.
Browse Terms →Complete Concrete Guide
Everything you need to know about concrete: planning, pouring, finishing, curing, and troubleshooting. Start here for your first project.
Read Guide →Foundation Crack Diagnosis
Vertical, horizontal, diagonal — crack orientation tells you the cause and severity. Use our orientation-based guide to assess any foundation crack.
Diagnose Cracks →Frequently Asked Questions
Common questions about calculating concrete volume, bags, and cost.
How much concrete do I need for a 10×10 slab?
A 10×10 foot slab at 4 inches thick requires approximately 0.62 cubic yards of concrete, or about 28 bags of 80-lb premix. Add 10% for waste, bringing the practical order to 0.68 cubic yards or 31 bags.
What is a cubic yard of concrete?
A cubic yard is 27 cubic feet of concrete — a cube measuring 3 feet on each side. It weighs approximately 2 tons (4,000 lb) when wet. At 4 inches thick, one cubic yard covers about 81 square feet.
How many bags of concrete are in a cubic yard?
One cubic yard of concrete requires approximately 45 bags of 80-lb premix, or 60 bags of 60-lb premix. For comparison, a ready-mix truck delivers concrete in full or partial cubic yards and is more cost-effective for pours over 1 yard.
How do I calculate concrete in bags?
First calculate cubic yards using the formula: Length (ft) × Width (ft) × Thickness (ft) ÷ 27. Then multiply cubic yards by 45 to get the number of 80-lb bags needed. For example, a 10×10 slab at 4 inches thick = 10 × 10 × 0.333 ÷ 27 = 0.62 yards × 45 = 28 bags.
How much does a cubic yard of concrete cost?
Ready-mix concrete delivered by truck typically costs $130–$170 per cubic yard, depending on mix strength and location. Bagged concrete (80-lb bags at ~$6 each) costs roughly $270 per equivalent cubic yard — more expensive per unit but practical for small jobs with no minimum order.
What's the difference between concrete and cement?
Cement is an ingredient in concrete — it's the fine gray powder (Portland cement) that acts as a binder. Concrete is the finished material made by mixing cement with water, sand, and gravel (aggregate). You pour concrete; you don't pour cement.
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