How to use the concrete calculator
Pick your project shape, type in the measurements and the calculator updates instantly. You get the volume in cubic yards (how ready-mix is sold), the number of 40, 60 or 80 lb bags if you are mixing yourself, and a cost range adjusted for your state.
- Slab, patio or driveway: enter length and width in feet and thickness in inches.
- Round slab: enter the diameter — the full distance across the circle.
- Post holes: enter hole diameter and depth in inches and how many holes you are filling.
- Leave the waste allowance at 5–10%. Uneven ground, spillage and form flex always eat some concrete.
The concrete formula
Concrete is measured by volume. Multiply length × width × thickness, with every measurement in feet, then divide by 27 to turn cubic feet into cubic yards.
Round slab = π × (Diameter ÷ 2)² × (Thickness ÷ 12) ÷ 27
80 lb bags = Cubic feet ÷ 0.60
Example: a 10 × 10 ft patio, 4 inches thick, is 10 × 10 × 0.333 = 33.3 cu ft. Divided by 27 that is 1.23 cubic yards, or about 1.36 yd³ with 10% extra. Mixing by hand, that is 62 bags of 80 lb concrete.
How thick should concrete be?
| Project | Typical thickness | Notes |
|---|---|---|
| Sidewalk / walkway | 4 in | Foot traffic only |
| Patio | 4 in | 5 in if a hot tub or heavy grill will sit on it |
| Shed or garage floor | 4–6 in | 6 in for heavy trucks or workshop equipment |
| Driveway | 4–5 in | 5–6 in for RVs, boats or heavy vehicles |
| Footings | 8–12 in | Check your local building code and frost depth |
Thicker is stronger, but each extra inch on a 10 × 10 slab adds about a third of a yard of concrete. Check your local building code for driveways and structural footings.
How much does concrete cost in 2026?
Ready-mix concrete typically runs $165–$200 per cubic yard delivered in 2026, before any short-load fee. Bagged 80 lb concrete costs about $6.50–$8.50 a bag at big-box stores. A professionally poured and finished 4-inch slab costs roughly $7.50–$13 per square foot, including base prep, forms, reinforcement and labor.
| Option | Typical price | Best for |
|---|---|---|
| 80 lb bags (DIY) | $6.50–$8.50 per bag | Post holes, small pads under ~1 yd³ |
| Ready-mix truck | $165–$200 per yd³ | Anything over ~1 yd³ |
| Short-load fee | $75–$150 | Orders under 4–5 yd³ |
| Pro-installed slab | $7.50–$13 per sq ft | Patios, driveways, garage floors |
| Stamped / decorative | $14–$25 per sq ft | Patios and pool decks |
Tips before you order
- Measure the thickness at several points. A slab that is supposed to be 4 inches but averages 4.5 inches uses 12% more concrete.
- Order 5–10% extra. Running short mid-pour leaves a cold joint that is weak and looks bad.
- Compact 4 inches of gravel base under slabs and driveways to stop cracking and settling.
- Use rebar or wire mesh in driveways and any slab that will carry vehicles.
- Book the truck for a dry, mild morning. Temperatures between 50 and 85°F give the best cure.
Concrete cost by state
10×10 ft patio, 4 in thick, poured & finished — estimated cost by state. Figures use the same assumptions as the calculator above.
| State | Low | High | vs. US avg |
|---|---|---|---|
| US average | $750 | $1,300 | — |
| Alabama | $653 | $1,131 | -13% |
| Alaska | $938 | $1,625 | +25% |
| Arizona | $720 | $1,248 | -4% |
| Arkansas | $645 | $1,118 | -14% |
| California | $915 | $1,586 | +22% |
| Colorado | $773 | $1,339 | +3% |
| Connecticut | $855 | $1,482 | +14% |
| Delaware | $780 | $1,352 | +4% |
| District of Columbia | $862 | $1,495 | +15% |
| Florida | $713 | $1,235 | -5% |
| Georgia | $683 | $1,183 | -9% |
| Hawaii | $990 | $1,716 | +32% |
| Idaho | $705 | $1,222 | -6% |
| Illinois | $825 | $1,430 | +10% |
| Indiana | $713 | $1,235 | -5% |
| Iowa | $713 | $1,235 | -5% |
| Kansas | $698 | $1,209 | -7% |
| Kentucky | $690 | $1,196 | -8% |
| Louisiana | $675 | $1,170 | -10% |
| Maine | $750 | $1,300 | 0% |
| Maryland | $765 | $1,326 | +2% |
| Massachusetts | $900 | $1,560 | +20% |
| Michigan | $750 | $1,300 | 0% |
| Minnesota | $803 | $1,391 | +7% |
| Mississippi | $630 | $1,092 | -16% |
| Missouri | $735 | $1,274 | -2% |
| Montana | $720 | $1,248 | -4% |
| Nebraska | $698 | $1,209 | -7% |
| Nevada | $780 | $1,352 | +4% |
| New Hampshire | $780 | $1,352 | +4% |
| New Jersey | $878 | $1,521 | +17% |
| New Mexico | $683 | $1,183 | -9% |
| New York | $900 | $1,560 | +20% |
| North Carolina | $668 | $1,157 | -11% |
| North Dakota | $720 | $1,248 | -4% |
| Ohio | $728 | $1,261 | -3% |
| Oklahoma | $660 | $1,144 | -12% |
| Oregon | $795 | $1,378 | +6% |
| Pennsylvania | $773 | $1,339 | +3% |
| Rhode Island | $825 | $1,430 | +10% |
| South Carolina | $660 | $1,144 | -12% |
| South Dakota | $675 | $1,170 | -10% |
| Tennessee | $675 | $1,170 | -10% |
| Texas | $690 | $1,196 | -8% |
| Utah | $720 | $1,248 | -4% |
| Vermont | $765 | $1,326 | +2% |
| Virginia | $720 | $1,248 | -4% |
| Washington | $825 | $1,430 | +10% |
| West Virginia | $683 | $1,183 | -9% |
| Wisconsin | $758 | $1,313 | +1% |
| Wyoming | $698 | $1,209 | -7% |
Frequently asked questions
How many bags of concrete do I need for a 10×10 slab?
A 10×10 ft slab 4 inches thick needs about 1.23 cubic yards, or 1.36 yd³ with 10% extra. That works out to roughly 62 bags of 80 lb concrete or 82 bags of 60 lb concrete.
How many cubic yards are in an 80 lb bag of concrete?
An 80 lb bag yields about 0.60 cubic feet, which is 0.022 cubic yards. It takes about 45 bags of 80 lb concrete to make one cubic yard.
Is it cheaper to buy bags or ready-mix concrete?
For less than about 1 cubic yard, bags are usually cheaper. Above that, ready-mix delivered by truck costs less per yard and saves hours of mixing, even after a short-load fee.
How much does a yard of concrete cost in 2026?
Most areas pay $165–$200 per cubic yard for delivered ready-mix in 2026. Small orders under 4–5 yards usually carry an extra short-load fee of $75–$150.
How much extra concrete should I order?
Plan on 5–10% extra. Uneven subgrade, form bulge and spillage mean you almost always use more than the pure math says.
How long does concrete take to cure?
You can usually walk on it after 24–48 hours and drive on it after about 7 days. Concrete reaches most of its design strength after 28 days.