Concrete Calculator
Enter the length, width, and depth of your slab or footing to calculate the volume of concrete needed.
Bag yield varies by product — check your specific concrete mix's coverage per bag to convert this volume into a bag count.
How slab volume is calculated
Volume for a rectangular slab or footing is simply length × width × depth. This calculator takes length and width in meters and depth in centimeters (since slabs are usually much shallower than they are wide), converts depth to meters, and multiplies the three together to get cubic meters.
From there, cubic meters converts to liters by multiplying by 1,000, to cubic feet by multiplying by about 35.31, and to cubic yards by multiplying by about 1.308 — useful if your supplier quotes concrete by a different unit.
Frequently asked questions
How do I calculate how much concrete I need for a slab?
Multiply the slab's length by its width by its depth (all in the same unit) to get the volume. For example, a 4 m × 3 m slab poured 10 cm deep is 4 × 3 × 0.1 = 1.2 cubic meters.
Should I order extra concrete?
Many contractors add 5-10% extra to account for spillage, uneven subgrade, and formwork imprecision — this calculator shows the exact geometric volume, so factor in a buffer yourself based on your project.
How many bags of concrete do I need?
That depends on the bag size and mix — check the yield (volume per bag) printed on your specific product, then divide the total volume shown here by that figure.