Concrete for a 4×14 slab

0.69 cubic yards (35 × 80 lb bags)

for a 4×14 ft slab 4 inches thick: 18.7 cu ft. Bag counts include 10% extra; at 6 inches you need 1.04 yards.

A 4×14 foot slab covers 56 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 18.7 cubic feet of concrete, or 0.69 cubic yards. That is a small enough pour for bagged mix: 35 bags of 80 lb at about $228.

Concrete for a 4×14 slab by thickness

ThicknessCubic yardsCubic feet80 lb bags60 lb bags40 lb bags
3 in0.5214263552
4 in0.6918.7354669
5 in0.8623.3435886
6 in1.04285269103
8 in1.3837.36992137

Bag counts include 10% extra for spillage and uneven ground. Cubic yards and cubic feet are the exact volume.

How it’s worked out

  1. Convert the thickness to feet: 4 in ÷ 12 = 0.333 ft.
  2. Multiply length × width × thickness: 14 × 4 × 0.333 = 18.67 cu ft.
  3. Divide by 27 for cubic yards: 18.67 ÷ 27 = 0.691 cu yd.
  4. Add 10% and divide by the bag yield: 20.53 ÷ 0.6 = 35 bags of 80 lb mix (rounded up).

Under the slab, plan on 4 inches of compacted gravel: about 0.69 cubic yards. For driveways and anything that carries a vehicle, go to 5 or 6 inches and add rebar or wire mesh.

Change the numbers

Concrete needed

0.69 cubic yards

18.7 cubic feet. With 10% extra, order 0.76 yards or 35 bags of 80 lb mix.

Area56 sq ft
Volume18.7 cu ft (0.69 cu yd)
80 lb bags35 (about $228)
60 lb bags46
40 lb bags69
Ready-mix to order1 yd (about $165 before delivery fees)
Weight of the slab1.4 tons

Other slab sizes

Questions

How many bags of concrete do I need for a 4×14 slab?
At 4 inches thick, a 4×14 slab takes 35 bags of 80 lb concrete mix, 46 bags of 60 lb mix or 69 bags of 40 lb mix, including 10% extra.
How many yards of concrete for a 4×14 slab?
0.69 cubic yards at 4 inches thick, 0.86 at 5 inches and 1.04 at 6 inches, before adding extra for waste.
How much does a 4×14 concrete slab cost?
The concrete alone for a 4 inch 4×14 slab costs about $228 in 35 bags of 80 lb mix (at about $7 a bag) or about $165 for 1 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $336 to $672 for 56 sq ft.
How much does a 4×14 slab weigh?
About 1.4 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).

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