Guide · Concrete
How Much Concrete Do I Need for a 10×10 Slab?
A 10×10 slab poured 4 inches thick needs 1.23 cubic yards of concrete — about 33⅓ cubic feet. Add a 10% waste allowance for uneven subgrade and spillage, and plan for 1.36 cubic yards. Mixing bags instead of ordering ready-mix? That’s 56 eighty-pound bags before waste, or 62 with waste built in.
Those are the headline numbers. Below is the exact math so you can verify it, a chart covering other common slab sizes, and guidance on thickness, bags vs. ready-mix, and cost. If you’d rather skip the arithmetic, use our free concrete calculator — enter your slab dimensions and it returns cubic yards plus 40-, 60-, and 80-lb bag counts in seconds.
Get cubic yards and bag counts for your exact slab dimensions — free, no sign-up.
Open the concrete calculator →Before waste. With a 10% allowance: 1.36 yd³, or 62 eighty-pound bags.
The math, step by step
= 10 ft × 10 ft × (4 ÷ 12) ft = 33.33 ft³
Cubic yards = 33.33 ÷ 27 = 1.23 yd³
- Convert thickness to feet. Four inches is 4 ÷ 12 = 0.333 ft.
- Multiply. 10 × 10 × 0.333 = 33.33 cubic feet.
- Convert to cubic yards. There are 27 cubic feet in a yard: 33.33 ÷ 27 = 1.23 yd³.
- Add waste. 1.23 × 1.10 = 1.36 cubic yards to order.
- Convert to bags. An 80-lb bag yields about 0.60 ft³: 33.33 ÷ 0.60 = 55.6, round up to 56 bags. With waste: 36.67 ÷ 0.60 = 61.1, round up to 62 bags.
Concrete needed for common slab sizes
Bag counts below are before waste and assume the standard 0.60 ft³ yield per 80-lb bag. Add 10% when ordering.
| Slab size | Thickness | Cubic feet | Cubic yards | 80-lb bags |
|---|---|---|---|---|
| 8×8 | 4″ | 21.3 | 0.79 | 36 |
| 8×8 | 6″ | 32.0 | 1.19 | 54 |
| 10×10 | 4″ | 33.3 | 1.23 | 56 |
| 10×10 | 6″ | 50.0 | 1.85 | 84 |
| 12×12 | 4″ | 48.0 | 1.78 | 80 |
| 12×12 | 6″ | 72.0 | 2.67 | 120 |
| 12×16 | 4″ | 64.0 | 2.37 | 107 |
| 16×16 | 4″ | 85.3 | 3.16 | 143 |
| 20×20 | 4″ | 133.3 | 4.94 | 223 |
Check the yield printed on your product label — most US 80-lb concrete-mix bags state 0.60 ft³, but specialty mixes can differ.
How thick should a 10×10 slab be?
Four inches is the standard for patios, walkways, and shed floors — and it’s what every number on this page assumes. Go thicker (5–6 inches) for driveways or anything carrying vehicles or heavy equipment. Whatever the thickness, the slab should sit on at least 4 inches of compacted gravel sub-base (our gravel calculator handles the sub-base math), and most slabs benefit from reinforcement — wire mesh or rebar on chairs, sized for the load. Our rebar grid calculator estimates bar counts, laps, and weight for a slab grid.
Bags or ready-mix for a 10×10 slab?
A 10×10 slab at 4 inches needs 56–62 eighty-pound bags — roughly two and a half tons of dry mix to haul, stage, and mix. That’s a full day with a mixer and a helper, at minimum, and the pour has to stay ahead of the set the whole time. The practical crossover point is around one cubic yard: below it, bags can make sense; at or above it — and a 10×10 slab is 1.23 yd³ before waste — ready-mix delivery is usually cheaper per yard and far less labor. Ready-mix suppliers have minimum-load charges (often 1–3 yards), so call ahead and confirm the short-load fee before you commit.
What does a 10×10 concrete slab cost?
Cost is just your volume times your local price. For bags: 62 bags × the per-bag price at your store. As a rough planning figure, eighty-pound bags commonly run about $5–$8 at US home centers, which puts bag material for this slab in the ballpark of $310–$500 — but treat that as a placeholder and check current shelf prices, which move by region and season. Ready-mix is typically quoted per cubic yard plus delivery and short-load fees, so get two quotes. Forming lumber, gravel sub-base, reinforcement, and labor sit on top of the concrete itself.
Pouring day: what to expect
If you go the bag route, know what you’re signing up for. A typical homeowner-grade 3.5-cubic-foot drum mixer handles about 2 eighty-pound bags per batch — 56 bags means roughly 28 batches. At 10–15 minutes per batch to load, mix, wheel, and place, that’s 5–7 hours of continuous mixing before screeding and finishing even start. You’ll want at least one helper: one person mixing, one placing and screeding. Keep the mix consistent batch to batch — measure the water rather than eyeballing it — or you’ll see the difference in the finished surface.
After the pour, protect your work. Concrete is walkable in 24–48 hours, ready for light use in about 7 days, and reaches full design strength around 28 days. Keep it damp for the first few days (a light misting or wet curing cover) and keep vehicles off a new slab for at least a week. Saw-cut control joints within 24 hours — typically one joint every 8–10 feet — to give shrinkage cracks somewhere to go.
How we calculate
Volume uses the rectangular-prism formula (length × width × depth), converted at 27 ft³ per cubic yard. Bag counts divide volume by 0.60 ft³ per 80-lb bag — the yield printed on most US concrete-mix bags; always confirm against your product label. The 10% waste allowance covers uneven excavation, spillage, and minor measurement differences; it is a planning figure, not an engineering specification. Assumes uniform slab thickness over a level, compacted subgrade.
Reviewed September 2026 · TrueMeasure
Frequently asked questions
How many 80 lb bags of concrete do I need for a 10×10 slab?
56 bags at 4 inches thick before waste — 62 with a 10% allowance. See our full reference on how many 80-lb bags are in a cubic yard.
How thick should a concrete slab be?
Four inches is standard for patios, walkways, and shed floors; driveways and heavier loads usually call for 5–6 inches. Frost depth, soil conditions, and local code can change the requirement — check before you form up.
Should I order ready-mix or mix bags for a 10×10 slab?
At 1.23 cubic yards, ready-mix is usually the better call: 56+ bags is roughly two and a half tons of material to haul and mix. Bags make sense below about one cubic yard.
Do I need rebar in a 10×10 slab?
Most residential slabs get welded wire mesh or a rebar grid to control cracking — concrete is strong in compression and weak in tension. A #3 bar grid at 18–24 inches on center is a common residential detail, but follow local code and any engineered plans. Our rebar grid calculator sizes the grid.
How much does a 10×10 concrete slab cost?
Materials only, budget roughly a few hundred dollars for bags (62 × the current per-bag price at your store) or a per-yard ready-mix quote plus any short-load fee. Forming lumber, gravel sub-base, reinforcement, and labor are on top. Prices vary widely by region — get local quotes.
Can I pour a 10×10 slab myself in one day?
With ready-mix, yes — a morning pour with two or three people is realistic. With bags, plan on a full hard day with a mixer and help; 56 bags is a lot of mixing, and concrete waits for no one once it’s wet.