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Concrete, gravel and mulch calculator

Measure each area, pick the material and get what to order: cubic yards, bags of concrete, or tons of gravel. Add as many areas as the job has.

Material
Units

Concrete to order

0 cubic yards

How it works

slab or footing = length x width x depth x how many
round hole      = 3.1416 x (diameter / 2)^2 x depth x how many
cubic yards     = cubic feet / 27, plus the extra for waste
bags            = cubic feet / bag yield, rounded up
gravel tons     = cubic yards x tons per cubic yard

Bag counts use the usual yields printed on premixed concrete: an 80 lb bag makes about 0.60 cubic feet, a 60 lb bag 0.45 and a 40 lb bag 0.30. Past about a cubic yard, a ready-mix truck is usually cheaper and much less work than mixing 45 bags.

Gravel weight depends on the stone. 1.4 tons per cubic yard is a fair middle for crushed stone and pea gravel; road base and wet sand run heavier, around 1.5 to 1.7, and lava rock far lighter. Ask the yard what their material weighs and put it in. Mulch is sold by the cubic yard in bulk or in 2 cubic foot bags, and 2 to 3 inches deep is the usual bed.

The 10% extra covers uneven ground, spillage and a slightly deep spot. Go higher for a rough excavation and lower for formed work on a level base.

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