10x20 Concrete Slab: Cost, Yards & Bags of Concrete
Quick answer: a 10 × 20 ft slab (200 sq ft) 4 inches thick needs 2.47 yd³ of concrete, 2.72 yd³ with 10% waste (order 2.75 yd³ of ready-mix) or 123 bags of 80-lb mix. Installed, it costs about $1,510 – $2,660 ($7.50 – $13.50 per sq ft); DIY materials run $660 – $980.
A 10 × 20 ft slab (200 sq ft) is a parking pad for one car, a boat or utility trailer, or a long side-yard storage area. It is just over the size where ready-mix starts to win on price, and because it may carry a vehicle, it gets rebar rather than mesh.
Concrete for a 10x20 Slab at 4, 5 and 6 Inches
| Thickness | Net volume | With 10% waste | Ready-mix order | 80-lb bags | 60-lb bags | 40-lb bags | Installed |
|---|---|---|---|---|---|---|---|
| 4 in (typical) | 2.47 yd³ | 2.72 yd³ | 2.75 yd³ | 123 | 163 | 245 | $1,510–$2,660 |
| 5 in | 3.09 yd³ | 3.40 yd³ | 3.5 yd³ | 153 | 204 | 306 | $1,610–$2,790 |
| 6 in | 3.70 yd³ | 4.07 yd³ | 4.25 yd³ | 184 | 245 | 367 | $1,710–$2,920 |
How Much Extra to Order
The table above adds 10%, the usual allowance for a formed slab on a graded base. Pick less only for rigid forms on a laser-flat base, more for soft or uneven ground:
| Waste allowance (4 in slab) | Concrete | 80-lb bags |
|---|---|---|
| 0% (exact volume) | 2.47 yd³ | 112 |
| 5% | 2.59 yd³ | 117 |
| 10% | 2.72 yd³ | 123 |
| 15% | 2.84 yd³ | 128 |
Bags or a Ready-Mix Truck?
| Option | What you buy | Concrete bill |
|---|---|---|
| 80-lb bags | 123 bags at $6.50 + mixer rental $75 | $875 |
| Ready-mix | 2.75 yd³ at $150 + $120 delivery + $140 short-load fee | $673 |
Ready-mix is $202 cheaper here and saves about 4.9 hours of mixing 123 bags. Bags only win below about 1.3 yd³, once the delivery and short-load fees are counted. Try your own prices in the bags vs. ready-mix calculator.
What a 10x20 Slab Costs
| Line item (4 in slab) | Basis | Cost |
|---|---|---|
| Ready-mix concrete + delivery | 2.72 yd³ at $150 + $120 | $527 |
| Forms | 60 lin ft at $2.20 | $132 |
| Vapor barrier | 200 sq ft at $0.35 | $70 |
| #4 rebar at 18 in | 200 sq ft at $1.25 | $250 |
| Broom finish | 200 sq ft at $0.75 | $150 |
| Labor (place & finish) | 200 sq ft at $5.00 | $1,000 |
| Direct cost | Before overhead and profit | $2,129 |
- Installed price: $1,510 – $2,660. The low end is a plain slab with lower-cost labor; the high end is the full scope above plus 25% contractor overhead and profit.
- Site prep and gravel base (excavation and 4 in of compacted stone): about $280 – $660 more.
- Permit, where one is needed: about $50 – $350.
Have a contractor's price? Put it into the concrete quote checker, or compare two or three bids side by side there.
Materials List for a 10 × 20 ft Slab
| Concrete | 2.75 yd³ ready-mix, or 123 × 80-lb / 245 × 40-lb bags |
|---|---|
| Gravel base (4 in compacted) | 2.84 yd³, about 4.0 tons |
| Forms | 6 × 2x4 boards 12 ft long, 24 stakes, 48 screws (60 lin ft) |
| Rebar (#4 at 18 in) | 296 lin ft = 15 × 20-ft sticks, 28 chairs |
| Or wire mesh (6x6) | 9 sheets of 5 × 10 ft, about $108 – $180 |
| Vapor barrier | 200 sq ft plus 6 in laps |
| Control joints | 2 panels of about 10 × 10 ft: 10 lin ft of saw cut, 1 in deep |
Recommended Specs for a Carport Or Parking Pad
| Thickness | 4 in for cars; 5 in for pickups, trailers and RVs |
|---|---|
| Strength | 3,500 PSI air-entrained; 4,000 PSI where de-icing salt is tracked in |
| Base | 4 to 6 in of compacted crushed stone |
| Reinforcement | #4 rebar at 18 in on chairs |
| Posts | Carport posts on their own footings (or thickened slab under each post), sized by the carport kit or engineer |
- For a trailer or pickup pad, pour 5 in thick: the 5-in row in the table below adds about a quarter more concrete.
- Slope the pad along its length so water runs off one short end, away from any building.
- Leave a gap with expansion joint material where the pad meets an existing driveway or garage slab.
Pour Day for a 10x20 Slab
- Crew time: about 7 crew-hours to set forms, place, finish and cut joints (0.035 h per sq ft for a broom finish).
- Trucks: 2.75 yd³ is 1 truck, about 14–22 minutes of unloading in total. Concrete must be placed within 90 minutes of batching.
- Reach: a truck chute reaches about 15–20 ft, enough for this slab if the truck can park beside it. If it can't, budget wheelbarrows or a line pump.
- Joints: saw-cut 4–12 hours after finishing with a wet saw, or 1–4 hours with an early-entry saw.
- Curing: foot traffic after 24–48 hours, cars after 7 days, full strength at 28 days.
Price Your Own 10x20 Slab
The calculator below starts at 10 × 20 ft, 4 inches. Change the thickness, finish or reinforcement, pick your state for local prices, and the Live Estimate updates with a blueprint of the joint and rebar layout.
Concrete Slab Cost & Volume Estimator
Precision multi-layer project budgeting: Materials, Sub-Base, Reinforcement, Labor & Equipment
Picking a location sets the ready-mix, excavation and labor rates below to that area's typical level. You can still type your own local prices afterwards. Slab prices by state.
Closer spacing uses more steel and raises the rebar cost.
Not charged when bagged concrete is selected.
A scaled plan of your slab: rebar grid at the spacing you chose, support chairs about every 3 to 4 ft, and the recommended control-joint saw cuts (2.5 times the thickness in inches, in feet, capped at 15 ft). It redraws as you change the inputs.
| Scope Item / Material Description | Amount |
|---|
Enter the total your contractor quoted. We compare it with a benchmark for the same slab and scope you set in the calculator: materials at your entered prices plus labor at the regional standard rate, before any overhead or profit. Make sure the calculator scope (base, rebar, finish, pump, demolition) matches what the bid includes.
Optional: enter the bid's line items to see where the markup sits
Enter the forecast for pour day. The check follows ACI 306R (cold weather) and ACI 305R (hot weather) and estimates the surface evaporation rate that drives plastic shrinkage cracking.
10x20 Slab Questions
About $1,510 to $2,660 installed for a 4-inch slab with forms, a broom finish and labor ($7.50 to $13.50 per sq ft), at U.S. average prices. DIY materials run about $660 to $980. Site prep and a gravel base add about $280 to $660.
At 4 inches thick with 10% waste: 123 bags of 80-lb mix, 163 bags of 60-lb mix or 245 bags of 40-lb mix. At 6 inches: 184 bags of 80-lb mix.
At 4 inches, 2.47 cubic yards (order 2.75 with waste); at 5 inches, 3.09 (order 3.50); at 6 inches, 3.70 (order 4.25). Ready-mix is sold in quarter yards, so round up.
Ready-mix. 2.75 yards delivered costs about $673, while 123 bags would cost about $875 and take roughly 5 hours of mixing. Bags only win below about 1.3 cubic yards.
A #4 grid at 18 inches each way needs about 296 linear feet of bar including laps: 15 twenty-foot sticks and about 28 chairs. Welded wire mesh instead takes 9 sheets of 5 x 10 ft.
Yes for one compact or mid-size car: 10 ft gives enough width to open doors on one side. Make it 12 ft wide if you need to open doors on both sides or park a full-size pickup.