Measuring for concrete
Measure the space the concrete will fill – inside the forms, not the outside – and take the thickness at several points, because the ground is rarely flat. Enter the thickness in inches or centimeters and check the unit: a thickness typed in feet makes the order twelve times too large. Split L-shaped pours into rectangles and add them.
Ordering and safety
Ready-mix is sold by volume and bags by yield, so the calculators give you both: the volume in cubic yards or cubic meters, and the bag count from the yield printed on your bag. Ask your supplier how much extra to allow. These tools estimate material quantity only – thickness, reinforcement, base and footings are design decisions for a qualified professional.