Concrete pad cost: sizing & pricing a small pad
A concrete pad is priced like any flatwork — area × your price per square foot, plus base, plus a contingency. The catch is that below roughly 100 sq ft the per-square-foot number stops behaving, because minimum charges and delivery fees, not concrete, dominate the bill.
The short answer
The formula is the standard flatwork one:
Total = ( area × price per sq ft + sub-base ) × (1 + contingency%)
Run it in the concrete slab cost tool. But on a pad small enough to measure in single digits of square yards, expect the effective rate to land well above the usual flatwork band. A 60 sq ft hot-tub pad and a 600 sq ft driveway take the same truck, the same crew, the same forms-and-finish trip and the same cleanup — only the concrete scales down. That fixed cost has to land somewhere, and on a small pad it lands on every one of those 60 square feet.
What a pad actually has to be
Pad size follows the equipment, not the other way round. The planning typicals below are a starting point for measuring — always confirm against the footprint and clearances your equipment manufacturer specifies:
| Pad | Typical size | Typical thickness |
|---|---|---|
| AC condenser | 3 × 3 ft | 4 in |
| Standby generator | 4 × 5 ft | 4–6 in |
| Hot tub / spa | 8 × 8 ft | 5–6 in |
| Small shed | 8 × 10 to 10 × 12 ft | 4 in |
| Trash / dumpster | 6 × 8 ft | 5–6 in |
| RV or trailer | 12 × 40 ft | 6 in |
Two rules of thumb sit behind that table. Make the pad 3 to 6 inches larger per side than the thing standing on it, so there is somewhere to stand and nothing overhangs the edge. And take thickness from the load: 4 inches for anything you only walk on, 5 to 6 inches once a filled spa, a generator or a wheel is sitting on it. Those are labeled planning typicals, not a structural design — a licensed engineer sizes concrete that carries real load.
A worked example: a 7 ft 6 in by 8 ft hot-tub pad
Six inches thick, because a filled spa is heavy.
- Area: 7.5 × 8 = 60 sq ft.
- Volume: 60 × (6 ÷ 12) = 30 cu ft = 1.11 cubic yards.
- Sub-base: 4 inches of compacted gravel = 60 × 0.333 ÷ 27 = 0.74 yd³, plus 10% compaction = 0.81 yd³, about 1.1 tons.
Now price the concrete two ways. Bagged, at 0.60 cu ft to an 80 lb bag: 30 ÷ 0.60 = 50 bags; at $6.35 a bag that is $317.50. Ready-mix, ordering 1.5 yards because plants sell in half-yard steps: 1.5 × $168 = $252, plus a $95 delivery and a $140 short-load fee = $487.
Bags win by $169.50 — and that is the honest answer at this size, even though 50 bags is 4,000 lb to carry, open and mix, which is a rented mixer and most of a day. Run your own numbers through ready-mix vs bags; the crossover usually sits near one cubic yard, which is about 60 sq ft at 6 inches or 81 sq ft at 4 inches.
Hired out, the same pad at $9 per square foot with an $85 base and a 10% contingency is (60 × $9 + $85) × 1.10 = $687.50, an effective $11.46 per square foot. Do not be surprised if the quote comes back as a flat number in the high hundreds instead: many contractors have a job minimum that a 60 sq ft pad never reaches, so the minimum is the price.
Why per-square-foot pricing misleads on pads
The published flatwork bands are built from jobs large enough to spread their fixed costs. A pad has the same fixed costs and almost no area to spread them over:
- Short-load fee. Ready-mix plants charge for undersized deliveries. On a 1.5-yard order that fee can exceed the concrete itself — in the example above, $140 against $252 of mix.
- Mobilization. Loading a truck, driving out, setting up and cleaning up costs the same for 60 sq ft as for 600.
- Forming and finishing. A small pad still needs forms, screeding, floating, edging and jointing. The perimeter-to-area ratio is worse on small pours, so proportionally there is more edge work, not less.
Treat any per-square-foot figure below about 100 sq ft as a sanity check on the concrete portion only, never as the whole price. The cost per sq ft by flatwork type table shows the bands the big jobs live in.
Three ways to bring a pad in cheaper
- Pour it with something else. The single biggest lever. If a driveway, patio or walkway is already going in, adding the pad to that pour costs you concrete and a little labor instead of a whole mobilization. A pad that costs $690 alone might add $200 to an existing pour.
- Do the dig and the base yourself. Excavation, a compacted gravel base and forms are the unskilled part of the job. Price the gravel with the gravel sub-base calculator; on our pad it is under a cubic yard.
- Use bags below a cubic yard. Under roughly 45 bags of 80 lb mix, the delivery and short-load fees make bags the cheaper buy. Above that, a truck wins on both price and labor — and it wins by a lot.
Edge cases worth knowing
A poured pad is not always the answer. For an AC condenser, a precast composite or concrete pad set on gravel is a common alternative — no pour, no cure, and it can be releveled. It is worth pricing against a 9 sq ft pour that needs 5 bags of mix.
Keep the pad separate from the house. A pad poured hard against a foundation ties two things that settle at different rates. Standard practice is an isolation joint between them; your contractor will handle the detail, and it is worth confirming it is in the scope.
Check permits before you form. Requirements vary by jurisdiction, and pads for generators, spas or anything with an electrical or gas connection are the ones most likely to need one. Ask your local authority first — it costs a phone call and can save a rebuild.
Slope it. A pad that holds water is a pad that spalls in the first freeze. A slight fall away from the house is standard on any exterior pad.
The bottom line
Size the pad from the equipment plus 3 to 6 inches per side, take thickness from the load, then price it as area × your rate + base, ×(1 + contingency). Expect a small pad to land above the published per-square-foot bands, and expect a contractor minimum to set the floor. Below about a cubic yard, bags beat a ready-mix delivery on price; above it, the truck wins outright. Every figure here is a planning estimate from numbers you enter, not a bid — get itemized written quotes from licensed, insured concrete contractors, and leave load-bearing concrete to a licensed engineer.
Where these conventions come from: American Concrete Institute publishes the reference standards, Portland Cement Association covers how the work is done in practice, and International Code Council is the source behind the local codes and permit rules your jurisdiction adopts.