Concrete for a 16×26 slab

5.14 cubic yards (255 × 80 lb bags)

for a 16×26 ft slab 4 inches thick: 138.7 cu ft. Bag counts include 10% extra; at 6 inches you need 7.7 yards.

A 16×26 foot slab covers 416 square feet. At the standard 4 inch thickness for a patio, walkway or shed floor, that is 138.7 cubic feet of concrete, or 5.14 cubic yards. At this size ready-mix is cheaper and far less work than bags: about 5.75 yards, roughly $949 before delivery fees, against $1,658 for 255 bags of 80 lb mix.

Concrete for a 16×26 slab by thickness

ThicknessCubic yardsCubic feet80 lb bags60 lb bags40 lb bags
3 in3.85104191255382
4 in5.14138.7255339509
5 in6.42173.3318424636
6 in7.7208382509763
8 in10.27277.35096781017

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: 26 × 16 × 0.333 = 138.67 cu ft.
  3. Divide by 27 for cubic yards: 138.67 ÷ 27 = 5.136 cu yd.
  4. Add 10% and divide by the bag yield: 152.53 ÷ 0.6 = 255 bags of 80 lb mix (rounded up).

Under the slab, plan on 4 inches of compacted gravel: about 5.14 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

5.14 cubic yards

138.7 cubic feet. With 10% extra, order 5.65 yards or 255 bags of 80 lb mix.

Area416 sq ft
Volume138.7 cu ft (5.14 cu yd)
80 lb bags255 (about $1,658)
60 lb bags339
40 lb bags509
Ready-mix to order5.75 yd (about $949 before delivery fees)
Weight of the slab10.1 tons

Other slab sizes

Questions

How many bags of concrete do I need for a 16×26 slab?
At 4 inches thick, a 16×26 slab takes 255 bags of 80 lb concrete mix, 339 bags of 60 lb mix or 509 bags of 40 lb mix, including 10% extra.
How many yards of concrete for a 16×26 slab?
5.14 cubic yards at 4 inches thick, 6.42 at 5 inches and 7.7 at 6 inches, before adding extra for waste.
How much does a 16×26 concrete slab cost?
The concrete alone for a 4 inch 16×26 slab costs about $1,658 in 255 bags of 80 lb mix (at about $7 a bag) or about $949 for 5.75 yards of ready-mix (at about $165 a yard, before delivery fees). Professionally poured slabs usually run $6 to $12 per square foot, about $2,496 to $4,992 for 416 sq ft.
How much does a 16×26 slab weigh?
About 10.1 tons at 4 inches thick (concrete weighs about 145 lb per cubic foot).

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