How to Calculate Concrete Yardage (The Right Way)
Getting concrete yardage wrong costs real money. Here's the formula every contractor needs — including waste factor, footings, and how to avoid short-load fees.
The basic formula
Concrete is ordered by the cubic yard. One cubic yard equals 27 cubic feet. The formula for a flat slab is straightforward:
Cubic Yards = (Length × Width × Thickness) ÷ 27
All measurements in feet. Convert inches to decimal feet first.
Example: 4 inches thick = 4 ÷ 12 = 0.333 feet
So a 20-foot by 30-foot driveway at 4 inches thick works out to:
(20 × 30 × 0.333) ÷ 27 = 7.41 cubic yards
Always add a waste factor
Never order exactly what the formula gives you. Concrete is never poured perfectly level — there are low spots, slight overflows, and the forms are never perfectly square. A standard waste factor is 8–10%.
7.41 yards × 1.08 = 8.0 yards (round up to nearest 0.5)
Don't forget footings
If your slab has footings around the perimeter (or on selected sides), calculate each footing separately and add it to the slab total. A standard perimeter footing is 12 inches wide and 12 inches deep.
Footing yardage per side = (Length × Width × Depth) ÷ 27
20-ft side: (20 × 1 × 1) ÷ 27 = 0.74 yards
All 4 sides of a 20×30 slab: ~2.96 yards additional
The short-load trap
Most concrete suppliers charge a short-load fee for orders under 6 cubic yards — often $100–$200 extra. Always check your totals before you call. If your estimate comes in at 5.8 yards, either add a small extra pour, combine with another job, or factor the fee into your bid.
⚠️ Short-load rule of thumb
Most plants charge short-load fees on orders under 6 yards. BuildPilot™ flags this automatically and adds the fee to your estimate if you're under the threshold.
Truck capacity
A standard ready-mix truck holds 10 cubic yards. For larger pours, divide your total yardage by 10 to determine how many trucks you need — and budget accordingly for pump trucks if access is tight.
Do it in 15 seconds with BuildPilot™
The formula above takes a few minutes with a calculator. BuildPilot™ does all of it automatically — yardage, waste factor, footings (you pick which sides), truck count, short-load detection, and equipment add-ons — the moment you enter the dimensions.
✅ The 2-minute target
With BuildPilot™, a typical concrete estimate — slab + footings + pump truck + delivery — takes under 2 minutes from the job site. You can send the branded PDF quote before you drive away.
Skip the calculator next time
BuildPilot™ handles yardage, footings, short-load alerts, and PDF quotes automatically.
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