Start at $8 a square foot if you need somewhere to start — Concrete Network's 2025 figures put a plain slab at $6.50 to $10.50. Then stop using it, because the square foot is not the thing you buy. You buy cubic yards. One yard covers 81 square feet at 4 inches and 54 at 6, so a single rate applied to both a patio and a driveway gives one of them away. On a 20 by 30 patio, one extra inch of thickness is two more cubic yards — about $320 at the $160 a yard one Northern California supplier publishes for 4,000 PSI mix. Price the volume. Check it against the square foot afterwards, never the other way round.
What does a cubic yard of concrete actually cover?
Twenty-seven cubic feet. Divide that by the thickness in feet and you have your coverage, which is why the number changes with every inch you add and why no square-foot rate survives contact with a real set of drawings.
| Slab thickness | Square feet per cubic yard | Cubic yards per 100 sq ft |
|---|---|---|
| 3.5 in (IRC minimum) | 92.6 | 1.08 |
| 4 in | 81.0 | 1.23 |
| 5 in | 64.8 | 1.54 |
| 6 in | 54.0 | 1.85 |
| 8 in | 40.5 | 2.47 |
Add 5 to 10 percent to whatever that gives you, then round up to the next half yard. Suppliers batch in quarter or half-yard increments anyway, and the overage is cheap insurance against the one mistake this trade does not forgive.
Coming up short is not a small error. A second truck arrives with its own delivery fee and its own short-load minimum, it arrives forty minutes later at best, and it leaves a cold joint through the middle of a slab the homeowner will stand on for twenty years. The material you throw away costs less than the callback.
What does the plant charge you that isn't in the price per yard?
Delivery, the day of the week, admixtures — and the clock running on the truck while you work. The per-yard price everybody quotes is a material price. It is not what lands on your invoice.
Townsend Concrete publishes its whole sheet, which is worth reading even if you buy three states away, because the structure is the same everywhere:
| Charge | Published amount |
|---|---|
| 5 sack, 3,000 PSI | $162/yd list, $152 contractor |
| 6 sack, 4,000 PSI | $170/yd list, $160 contractor |
| Delivery, per load | $120 to $350 by zone |
| Saturday delivery | $100 additional |
| Sunday delivery | Weekday fee doubled |
| Accelerator | $13 per 1% per yard |
| Unload time included | 5 minutes per cubic yard |
| Time over the allowance | $10 per 5 minutes |
Now run a 4 by 40 sidewalk, 4 inches thick. That is 160 square feet, about 2 cubic yards, so you order 2.5. The concrete is $405. The delivery fee is $120 on top of it, which makes your real cost $210 a yard against a $162 list price — 30 percent above the number you were quoted on the phone.
The unload allowance is the line that catches people. Two and a half yards buys twelve and a half minutes. Ten and a half yards buys fifty-two. Chuting straight into a driveway beats that comfortably. Buggying ten yards through a side gate to a backyard patio does not, and at $10 every five minutes an hour of overrun is $120 you did not put in the estimate — the same as the delivery fee, for standing still.
Which variables actually move your square-foot number?
Five of them, and only one is the concrete itself.
| Variable | What it does |
|---|---|
| 4 in to 5 in thickness | Yardage up 25%. Labor barely moves |
| 4 in to 6 in | Yardage up 50% |
| Code-compliant base course | Four more inches of excavation, plus aggregate and haul-off |
| Wire mesh to #4 rebar at 18 in o.c. | About 1.5 linear feet of bar per square foot of slab, laps included |
| Broom finish to stamped | Concrete Network: $6.50–$10.50/sq ft becomes $10–$20/sq ft |
| Chute access to pump or buggy | Unload allowance blown, plus pump rental or a second body |
I am giving you a quantity for the rebar rather than a price on purpose. Published per-square-foot reinforcement figures disagree with each other by a factor of four, and your steel supplier's foot rate this month beats any of them. Take the 1.5, multiply by your slab area, price it yourself.
How do you price the concrete nobody sees?
Separately from the slab, as its own volume, before you total anything. Three quantities live below grade and none of them appear in a square-foot calculation.
The thickened edge. A 20 by 30 patio has 100 linear feet of perimeter. Put a 12-inch by 12-inch edge on it and you have added 100 × 1 × 0.67 = 67 cubic feet, or 2.5 cubic yards. The flat slab at 4 inches wanted 8 yards. You now need 10.5 — a third more concrete, invisible on a plan view, and the most commonly missed quantity in residential flatwork.
The base. The IRC's R506 language, in the 2021 edition Colorado adopted, calls for a 4-inch base course of clean graded sand, gravel, crushed stone or crushed concrete under a slab on ground, with a 10-mil vapor retarder meeting ASTM E1745 Class A lapped at least 6 inches. That base is not optional and it is not free. It is four inches of extra dig, aggregate delivered and compacted, and dirt hauled somewhere. Check your local amendments before you price it — jurisdictions edit this section constantly.
The dig itself. A 4-inch slab on a 4-inch base means an 8-inch excavation, so a 600 square foot patio produces about 15 cubic yards of spoil. Somebody moves that. If it is you, it is a day and a dump fee that belongs on the estimate as a line item rather than in your gross profit.
For the labor against all of it, BLS put the median cement mason and concrete finisher at $57,020 a year in May 2025, with masonry workers overall spanning $39,670 at the 10th percentile to $91,350 at the 90th. That is a wage, not a cost. Run it through your own burdened rate before it goes anywhere near a customer.
What this misses
The concrete is not what is moving. The BLS producer price index for ready-mix manufacturing read 401.896 in July 2026 against 393.322 a year earlier, about 2.2 percent. Material inflation is not your pricing problem this year. Access is, and so is what it costs to move dirt. Neither one shows up in a national average.
Published per-square-foot ranges bundle different scopes. Concrete Network's $6.50 to $10.50 is a plain slab. Whether that includes excavation, base, forms and reinforcement varies by whoever compiled it, and the gap between the thinnest and fattest reading of "slab" is wider than the range itself. Use it to check your own arithmetic, not to replace it.
Structural work is a different article. Engineered footings, post-tension, anything carrying a stamped design — the volume math still holds, the pricing method does not, and you should be reading a spec rather than a blog.
The arithmetic here is not hard. It is just long, and it has to happen while you are standing in somebody's yard with a tape measure and no calculator. BidWalk works the yardage out while you are still walking the site, so the thickened edge gets counted in the place where you can see it.
