Concrete Calculator
Concrete volume and bag count for any slab.
Enter the length, width, and thickness of your concrete slab or footing to get the volume in cubic meters. The calculator also converts that into the number of 40 kg bags to buy. It uses the standard fresh-concrete density of 2,400 kg/m³, so add 5–10% extra for spillage on real jobs.
How it's calculated
Cubic meters = length × width × (depth in cm ÷ 100). Bags = volume × 2,400 kg/m³ ÷ 40 kg, rounded up.
Frequently asked questions
How do you calculate concrete volume?
Multiply length × width × depth, all in the same units. A 3 m × 2 m slab that is 10 cm thick needs 3 × 2 × 0.1 = 0.6 cubic meters of concrete.
How many 40 kg bags make one cubic meter?
Fresh concrete weighs about 2,400 kg per cubic meter, so divide that by the bag weight. A 40 kg bag makes roughly 1/60 of a cubic meter — our calculator does this for you.
Should I order extra concrete?
Round up and add 5–10% extra for spillage, uneven ground, and formwork gaps. Running out mid-pour is far more expensive than one leftover bag.