Pour confidently.
Cubic yards of concrete for slabs, footings, and round pours. Waste factor included so your order matches your project.
How we calculated this
For rectangular pours, the calculator multiplies length by width by thickness to get raw volume. For round pours, it uses π × radius² × thickness. Thickness is entered in inches (or centimeters) and converted to the same unit as length and width before the multiplication.
Imperial results convert from cubic feet to cubic yards by dividing by 27 (since 1 cubic yard = 27 cubic feet). Metric results stay in cubic meters directly. Yards and meters are how concrete is sold, so this is what you'll actually order.
A waste factor of 10% is standard for most slab pours — it covers spillage, uneven subgrade, over-excavation, and the practical reality that concrete trucks don't come back for tiny shortages. Use 5% for very flat, well-prepared sites; 15% for irregular shapes or rough subgrade.
The final number is rounded up to the nearest 0.01 cubic yards or meters because concrete suppliers typically sell in increments of 0.25 yards. When you order, round up again to the nearest quarter-yard to account for truck minimums.
One quarter-yard short: why concrete estimation has zero margin for error
A contractor in Ohio told me about a driveway pour that went sideways in 2024. The homeowner measured his driveway at 18 × 50 feet, plugged it into a calculator online, and ordered 11 cubic yards. What he forgot was that the apron near the garage was 6 inches thick, not 4. That two-inch difference across 18 × 8 feet added 0.9 yards he didn't order. The truck ran dry 6 feet from the end. The batch plant couldn't send another truck for 3 hours. The cold joint where the two pours met cracked through by the following spring.
Concrete estimation comes down to three decisions: how thick, how much waste to add, and whether to use bags or call a truck. The volume formula itself — length times width times thickness divided by 27 — is the easy part.
How we calculated these numbers▾
Coverage and bag yields use Quikrete and Sakrete 80-lb bag specifications. Ready-mix pricing reflects 2025-2026 batch plant quotes from the National Ready Mixed Concrete Association (NRMCA) regional data. PSI recommendations follow ACI 332 residential standards.
The formula: cubic feet to cubic yards
Concrete is sold by the cubic yard. One cubic yard equals 27 cubic feet. The formula for any rectangular slab is:
Volume = length (ft) × width (ft) × thickness (ft) ÷ 27
The one thing people get wrong every time: thickness has to be in feet, not inches. A 4-inch slab is 0.333 feet thick (4 ÷ 12). Forget that conversion and your order is off by a factor of 12. The calculator at the top handles this automatically — you enter inches and it converts.
For a quick mental shortcut on 4-inch slabs: divide your total square footage by 81. That gives you cubic yards. A 10 × 10 patio (100 sq ft) at 4 inches = 100 ÷ 81 = 1.23 yards. Round up to 1.5 and you're safe.
How thick should your slab be?
Thickness is the single biggest variable in how much concrete you need. Going from 4 inches to 6 inches on a 400 sq ft driveway adds 50% more concrete — roughly 2.5 extra cubic yards, or $375 more in material. But skipping that thickness on a driveway that parks heavy vehicles means cracking within 3-5 years and tearing it out to start over. The thickness table above isn't a suggestion — it's what the concrete will demand from you eventually.
Bags vs ready-mix delivery
Bags (80 lb) | Ready-mix truck | |
|---|---|---|
| Cost per yd³ | $315–405 | $125–175 |
| Minimum order | 1 bag | 1 yd³ (most plants) |
| Time to pour 1 yd³ | 3–4 hours mixing | 10 minutes |
| Best for | Fence posts, small pads, repairs | Driveways, patios, slabs, footings |
| Quality control | Variable (your mix ratio) | Consistent (batched to spec) |
Ready-mix is cheaper AND better quality for anything over half a yard. Bags are for small, isolated pours where truck access is impossible.
How far does a yard of concrete go?
How much extra to order
Never order the exact calculated amount. Subgrade is never perfectly level, forms shift slightly during the pour, and some concrete always gets left in the chute, spilled, or wasted. The question is how much buffer to add.
The calculator above adds a 10% waste factor by default, which handles most residential pours. If your site is unusually flat and simple, you can mentally reduce to 5%. If you're pouring steps, curved edges, or anything on a slope, bump to 15%. The golden rule: half a yard left over costs $75. Coming up half a yard short costs $500+ in emergency delivery fees, cold joint repairs, and your own frustration.
Composite illustration based on typical project dimensions, regional contractor pricing, and 2026 material costs. Not a specific real project.
Reinforcement: rebar vs wire mesh vs fiber
Rebar grid | Wire mesh | Fiber mix | |
|---|---|---|---|
| Best for | Driveways, structural slabs | Patios, walkways | Small pads, non-structural |
| Cost | $0.50–1.00 / ft² | $0.15–0.30 / ft² | $0.10–0.20 / ft² (added to mix) |
| Crack control | Excellent — holds cracks tight | Good — limits crack width | Fair — reduces surface cracking |
| Installation | Set on chairs before pour | Lay flat, pull up during pour | Pre-mixed, no install |
Rebar is the standard for any load-bearing slab. Wire mesh is the budget option for patios. Fiber is a supplement, not a replacement for steel.
A common mistake — and one the rebar calculator can help you avoid — is laying wire mesh flat on the subgrade and pouring concrete on top. The mesh needs to be in the middle third of the slab to work — pull it up during the pour or set it on rebar chairs beforehand. Mesh sitting on the ground does nothing for crack control.
Cost to pour concrete in 2026
DIY | Professional | |
|---|---|---|
| Concrete (per yd³) | $125–175 | $125–175 |
| Forms + rebar | $50–100 | Included |
| Labor | $0 (hard labor) | $8–15 per ft² |
| Finishing | Broom finish (DIY-friendly) | Stamped, exposed, or troweled |
| 10×10 slab (4") total | $250–350 | $800–1,500 |
DIY is viable for simple slabs under 100 sq ft. Larger pours need a crew — concrete waits for nobody.
The hidden cost of DIY concrete is time pressure. Once the truck arrives, you have about 90 minutes before the concrete starts setting. A 10×10 pad is manageable alone. A 400 sq ft driveway needs 3-4 people working in coordinated sequence: one directing the chute, one spreading, one screeding, one bull-floating. If you don't have a crew, hire the pour out.
Sources
- Portland Cement Association — Concrete Basics — Industry reference for concrete volume calculation
- Concrete Network — How Much Concrete Do I Need — Waste factor recommendations for residential pours
Frequently asked
How much concrete do I need for a 10×10 slab?
For a standard 4-inch thick 10×10 ft slab with 10% waste, you need about 1.4 cubic yards. At 6 inches thick it's 2.1 yards. Use the calculator above for your exact dimensions.
Why do I need to add a waste factor?
Real-world pours always use more than theoretical volume. Subgrade settles, forms bulge, concrete spills during placement, and finishers prefer working with a slight excess. 10% waste is standard; anything less risks running out mid-pour — which is expensive because another truck delivery incurs a minimum charge.
What's the minimum concrete truck order?
Most ready-mix suppliers have a 1 cubic yard minimum, and charge a short-load fee for anything under 3-5 yards. For pours under 1 yard, bagged concrete (80 lb bags ≈ 0.02 yards each) is often cheaper even accounting for mixing time.
How many bags of concrete equal a cubic yard?
A cubic yard of concrete is roughly 60 bags of 50-lb premix, 45 bags of 60-lb, or 40 bags of 80-lb. Bagged concrete is practical for pours under half a yard; above that, ready-mix is more cost-effective.
What thickness should my slab be?
Sidewalks and patios: 4 inches. Driveways for passenger cars: 4 inches. Driveways for trucks or RVs: 6 inches. Garage floors: 4-6 inches. Footings: 8-12 inches or deeper in cold climates. Check local code — frost depth requirements vary.
How is round concrete calculated differently?
For round pours (tube forms, round patios, fence posts), the calculator uses π × radius² × thickness instead of length × width × thickness. Enter the diameter in the length field and leave width alone — it's ignored for round shapes.
Does this include aggregate, cement, and water?
The cubic yardage is for mixed concrete (what you order from a truck or buy in bags). It already includes all components. You don't need to calculate cement, sand, gravel, and water separately unless you're mixing from scratch.
What's the difference between cubic yards and yards of concrete?
They're the same thing — 'yards' of concrete is shorthand for cubic yards. A 'yard' of concrete means one cubic yard (3 ft × 3 ft × 3 ft = 27 cubic feet).
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