MotionShine01 / Volume
Length × width × depth
Every size is turned into feet, multiplied, and shown in cubic feet, cubic yards and cubic metres.
Free tool
Concrete calculator, yards and bags.
Pick a slab or footing, a round column or hole, or a flight of steps, type the sizes in feet, inches or metres, and see how much concrete you need in cubic yards, cubic feet and cubic metres, with extra for waste. Then see how many bags of pre-mix that is: the bag yields come from the QUIKRETE Concrete Mix data sheet, and you can type the yield printed on any other bag.
Bag yields: QUIKRETE Concrete Mix data sheet, read 17 Oct 2026. Other brands print their own yield on the bag.
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Measure once
Volume, waste, bags.
02 / Waste
Order a little more
Uneven ground and spills eat concrete. Ten percent extra is a common margin.
03 / Bags
For small jobs
Pre-mix bags suit small jobs; for big pours ready-mix by the cubic yard is usually easier.
Questions
Good to know.
How much concrete do I need for a slab?
Length × width × thickness. A 10 × 10 ft slab 4 inches thick is about 33.3 cu ft, or 1.23 cubic yards, before waste.
How many 80 lb bags are in a cubic yard?
About 45, at 0.60 cu ft a bag (27 ÷ 0.6).
How much extra should I order?
Many people add 5 to 10 percent for waste and uneven ground.
Can I use metric?
Yes. Pick metres or centimetres; the result shows cubic metres too.
Where do the bag yields come from?
The QUIKRETE Concrete Mix data sheet, read on 17 October 2026. Check the yield printed on your bag.