How much concrete do you need for a 10×12 slab?

A 10×12 ft slab poured 4 inches thick needs 1.48 cubic yards (40 cu ft) of concrete. With 10% extra for waste, buy 74 bags of 80 lb premix or order 1.63 yards of ready-mix.

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Your results

Concrete to buy (incl. 10% extra)1.63 cu yd
80 lb bags74
60 lb bags98
40 lb bags147
Exact volume40 cu ft (1.48 cu yd)
How much concrete do you need for a 10×12 slab — diagram

Concrete for a 10×12 slab at different thicknesses

The slab covers 120 square feet. Every extra inch of thickness adds about 0.37 cubic yards. Quantities below include 10% for waste.

ThicknessCubic yards80 lb bags60 lb bags40 lb bags
3.5 in1.436586129
4 in1.637498147
5 in2.0492123184
6 in2.44110147220
8 in3.26147196294

Bags or ready-mix for this size?

At 1.63 cubic yards you are in the gray zone between bags and a truck. 74 bags of 80 lb weigh about 5,920 lb in total — get a ready-mix quote (ask about short-load fees) and compare it with the bag price before deciding.

How heavy is a 10×12 slab?

Normal-weight concrete weighs about 150 lb per cubic foot, so a 4-inch 10×12 slab weighs roughly 6,000 lb (3 tons) once cured. Make sure your base is compacted gravel on firm, undisturbed soil.

The math

10 ft × 12 ft × (4 in ÷ 12) = 40 cu ft 40 cu ft ÷ 27 = 1.481 cu yd +10% waste = 44 cu ft 44 ÷ 0.6 cu ft per 80 lb bag = 74 bags (rounded up)

Common questions

How many 80 lb bags of concrete for a 10x12 slab?

74 bags for a 4-inch slab including 10% extra (67 with no extra). At 6 inches thick you need 110 bags.

How many yards of concrete for a 10x12 slab 6 inches thick?

2.44 cubic yards including 10% extra, or 2.22 yards exactly.

How many 60 lb bags for a 10x12 slab?

98 bags of 60 lb concrete for a 4-inch slab with 10% extra.

Want the full method, tips and other sizes? See the concrete calculator guide.

Last reviewed November 1, 2026. Results are estimates — confirm with your supplier.

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