Concrete calculator

Volume and bag count for a slab or pad.

How it works

Concrete volume is length × width × thickness. A waste allowance covers uneven subgrade and spillage. Premix bags suit small jobs; for larger pours, order ready-mix.

How to measure

Measure the inside of the forms. Check thickness at several points and use the average.

Tips

Above roughly 1 yd³, ordering ready-mix is usually cheaper than bags.
Bag yield varies by brand; go by the yield printed on the bag.
For structural elements, consult a licensed engineer.

More tools

Brick and block

How many bricks or blocks a wall takes.

Mortar

Mortar volume, cement and sand for a masonry wall.

Gravel

Gravel volume and tonnage for a path or base.