Concrete Pad Calculator
A pad is just a small slab with a job — shed base, AC platform, equipment footing. Enter its dimensions and the concrete pad calculator gives you yards, bags and cost on the spot.
Concrete needed
2.96 yd³
80.0 ft³
Estimated cost
$489
at $165 per yd³
Approx. weight
10,640 lb
≈ 5.3 tons
Bagged mix
134
80-lb bags
178
60-lb bags
267
40-lb bags
Before you order: add about 10% for uneven subgrade and spillage — that's 3.26 yd³ or 147 × 80-lb bags.
Formula
Pad volume is the same math as any flat pour:
volume (ft³) = length (ft) × width (ft) × [thickness (in) ÷ 12]
Then convert to what you order:
- Cubic yards = cubic feet ÷ 27
- Bags = cubic feet ÷ yield (80-lb: 0.60 ft³, 60-lb: 0.45 ft³, 40-lb: 0.30 ft³)
- Estimated cost = cubic yards × price per yard
Example
- A shed pad measures 10 ft × 12 ft, poured 4 inches thick: 4 ÷ 12 = 0.333 ft.
- Volume: 10 × 12 × 0.333 = 40 ft³.
- Cubic yards: 40 ÷ 27 = 1.48 yd³ — order about 1.75 yd³ with the 10% allowance.
- Bags: 40 ÷ 0.60 = 66.7 → 67 × 80-lb bags (74 with waste).
- Cost at $165 per yard: 1.48 × 165 ≈ $245.
Frequently Asked Questions
How thick should a concrete pad be?
Three to four inches suits most pads: sheds, AC condensers, generators and hot-tub bases. A pad carrying a vehicle or heavy equipment should be five to six inches, with reinforcement. Whatever the thickness, sit the pad on 4 inches of compacted gravel.
How many bags of concrete do I need for a 10×10 pad?
A 10 × 10 ft pad at 4 inches thick is 33.3 ft³, or 1.23 cubic yards — 56 of the 80-lb bags (62 with a 10% allowance). At that size a ready-mix truck is usually cheaper per yard and far less work.
Does a pad need rebar or wire mesh?
For light-duty pads, 6×6 wire mesh or fiber-mixed concrete is usually enough. Pads carrying vehicles, sheds or equipment benefit from #4 rebar on 18–24 in. centers. Neither changes the concrete volume, but both change your materials list.
Should the pad be flush with the ground or raised?
Raised forms (a 3–4 in. curb of concrete above grade) keep water and mud off the pad and make it easier to sweep. Any form height above 4 inches needs stakes every couple of feet to hold the pressure of the wet concrete.