Concrete Pad Cost Calculator
Calculate concrete for AC unit pads, shed bases, generator pads, hot tubs, and equipment slabs. Includes bag count and cost estimate.
Pad Calculator
// Pad Estimate
Concrete Pad Sizing Guide by Application
| Application | Recommended Size | Thickness | Notes |
|---|---|---|---|
| Small AC condenser | 30"×30" to 36"×36" | 4" | 3–4" beyond unit footprint all sides |
| Large AC condenser | 36"×42" to 42"×48" | 4" | Check unit specs for footprint |
| Whole-home generator | 36"×60" to 48"×72" | 4–6" | Must match generator base dimensions |
| Hot tub / spa (6-person) | 96"×96" to 108"×108" | 6" | Reinforced — hot tubs weigh 3,000+ lbs filled |
| Shed foundation (10×12) | 10'×12' | 4" | May need perimeter thickening for bearing walls |
| Pool equipment pad | 48"×60" | 4" | Size to fit pump + filter + heater |
Small pads = bagged concrete. Most AC pads, generator pads, and small shed bases are under 0.5 cubic yards — far too small to order ready-mix (minimums are typically 1 yard, with short-load fees). Quikrete or Sakrete 80lb bags are the right choice for anything under 1 yard.
When to Use Bags vs. Ready-Mix
For most equipment pads, bagged concrete is the right call. A standard 3×3 AC pad at 4 inches needs only about 0.1 cubic yards — that's roughly 5 bags of 80lb Quikrete. A ready-mix truck delivers a minimum of 1 yard ($120–$180 in material alone, plus a $75–$150 short-load fee). The math strongly favors bags for any pad under about 1 cubic yard.
For larger pads like a 10×12 shed foundation (about 1.5 yards) or a hot tub pad at 8×8 feet (about 1.2 yards), it's worth getting a ready-mix quote — the cost may be similar, but the pour will be faster and easier with a truck.
Frequently Asked Questions
- How thick should a concrete pad be for an AC unit?4 inches is the standard specification for residential AC condenser pads. The pad should extend 3–4 inches beyond the unit's footprint on all sides. Most residential condensers sit on a 30"×30" to 36"×42" pad.
- Can I pour a concrete pad by myself?Yes — small pads (AC units, small generators) are among the easiest DIY concrete projects. A few 80lb bags of fast-setting Quikrete, a wheelbarrow, and a couple of hours is all you need. No mixer required for pads under 10 bags.
- Do I need to reinforce a small concrete pad?For AC unit pads and small equipment pads, wire mesh or rebar is optional but recommended — it costs little and significantly reduces cracking over time. For hot tub pads and anything that will bear significant weight, #3 or #4 rebar on an 18-inch grid is strongly recommended.
- How long until I can set equipment on a new concrete pad?Wait at least 48–72 hours before placing light equipment (AC units). For heavy equipment, hot tubs, or generator loads, wait 7 days minimum. Full 28-day cure is required for maximum strength, though most residential pads can accept normal loads after 7 days.