Show the math
- Convert to feet (inches ÷ 12, centimeters ÷ 30.48): Length 10 ft; Width 10 ft; Thickness 4 in = 0.3333 ft
- Volume = 10 × 10 × 0.3333 × 1 = 33.3333 ft³
- Net volume = 33.3333 ft³ ÷ 27 = 1.2346 yd³ (× 0.0283168 = 0.9439 m³)
- Order quantity = 1.2346 yd³ × (1 + 10%) = 1.358 yd³ = 36.6667 ft³
- 80 lb bags = 36.6667 ft³ ÷ 0.6 ft³ per bag = 61.11 → 62 bags (always round up)
- Weight = 36.6667 ft³ × 150 lb/ft³ = 5,500 lb
What this slab is used for
A 10×10 ft slab (100 ft²) is the classic small project: a patio big enough for a table and four chairs, a base for an 8×10 shed, a grill and seating corner, or a pad for a hot tub. Hot tubs are the exception to “small and light”. A full tub can weigh several thousand pounds, so follow the manufacturer’s slab requirements for thickness and reinforcement before you pour.
Four inches is the usual choice for a patio and for a lightly used shed. If the pad will carry a heavy shed full of equipment or a filled hot tub, go to 5 or 6 in and ask the manufacturer or an engineer about steel. Three inches saves concrete but leaves little margin and is rarely worth it.
Concrete for a 10×10 ft slab at each thickness
At about 1.36 yd³ this sits right on the boundary between bags and a truck. Mixing 62 bags of 80 lb mix is a long day for two people, while a truck order this small will usually trigger a short-load fee. Many owners of a 10×10 slab rent a drum mixer and pour half the slab at a time with a planned joint at the middle, which is a good use of a control joint.
| Thickness | Net yd³ | Order yd³ | Order m³ | 80 lb bags | 60 lb bags | Weight |
|---|---|---|---|---|---|---|
| 3 in | 0.93 | 1.02 | 0.78 | 46 | 62 | 4,125 lb |
| 4 in | 1.23 | 1.36 | 1.04 | 62 | 82 | 5,500 lb |
| 5 in | 1.54 | 1.70 | 1.30 | 77 | 102 | 6,875 lb |
| 6 in | 1.85 | 2.04 | 1.56 | 92 | 123 | 8,250 lb |
The formula is 10 × 10 × thickness ÷ 12 ÷ 27 for the net volume. The order adds 10% for waste and rounds the bag counts up. Use the calculator above for another thickness or waste allowance.
Bags or ready-mix for 10×10 ft?
Bags: 62 bags of 80 lb mix at 4 in, a total of 4,960 lb of dry product. Ready-mix: 1.36 yd³, material about $220–$665 at the published range, last verified 2026-10-04, before delivery and short-load fees. Bagged concrete for this slab costs about $341–$496. Because the order is under two cubic yards, price both routes: the delivery and short-load fees can make bags competitive. See bagged vs ready-mix.
What to watch for
- Measuring the slab from the house wall and forgetting the form thickness: a 10 ft clear patio may need 10 ft 3 in of formwork.
- No slope. Give the slab about 1/8 to 1/4 in of fall per foot away from the building.
- Pouring on topsoil. Strip it and compact a stone base first.
- Skipping the joint. A single saw cut across the middle (5 ft) or a pair of cuts makes a 10×10 slab far less likely to crack at random.
Layout and joints
A 10×10 ft square is also the natural size for a four-panel layout with joints every 5 ft, or two panels with one joint, depending on how you prefer to finish it.
For a 4 in slab, joint spacing of 8 to 12 ft is the usual range, with a 15 ft maximum for any thickness. Read the control joints guide for depth and timing.
Before you order
- Measure the forms, not the excavation, and check the thickness in several places.
- Add the volume of any thickened edge, apron or step separately.
- Plan the base: use the gravel base calculator to estimate stone for 100 ft².
- If the design calls for steel, estimate it with the rebar calculator.
- Put the quantity on the Pour List to combine it with footings and steps.
Frequently asked questions
How many yards of concrete for a 10×10 slab?
1.23 yd³ net at 4 in, 1.36 yd³ with 10% waste.
How many bags of concrete for a 10×10 slab?
62 bags of 80 lb mix or 82 bags of 60 lb mix at 4 in with 10% waste.
How much does a 10×10 slab weigh?
About 5,500 lb (2.75 US tons) at 4 in with 10% waste, using 150 lb/ft³.
How many yards for a 10×10 slab at 6 in?
2.04 yd³ with 10% waste.
How much does a 10×10 concrete slab cost in materials?
About $220–$665 for ready-mix concrete at 4 in, before delivery fees, based on the ranges on the cost page (verified 2026-10-04).
Sources
Estimate only. Results depend on the numbers you enter, ground conditions and your supplier. For structural work consult a licensed engineer and follow local codes. Brand names such as Quikrete and Sakrete are used only to cite published product data. This site is not affiliated with any brand.