Concrete calculator.
Give it a slab, a footing, or a round column and it works out how much concrete to order: cubic yards, cubic feet, and how many 60 or 80 lb bags for a small pour. It folds in a waste add so you are not scrambling for one more bag with the truck idling.
The 10 percent overage covers spills, a low spot in the grade, and a form that bows out. Running short mid-pour is the one thing you do not want, so round up, not down.
Your shape drawn to the numbers you entered, with the cubic-yard result called out. Screenshot it for the yard or the crew.
The same math you’d do on the tailgate.
Length times width times thickness gives cubic feet, with the thickness turned from inches into feet first. Divide by 27 to get cubic yards, because a cubic yard is 3 by 3 by 3 feet. A 20 by 20 ft slab at 4 in works out to about 133 cubic feet, just under 5 yards.
A column is pi times the radius squared times the height. Take half the diameter for the radius, put everything in feet, and you get cubic feet, then divide by 27 for yards. A 12 in tube 8 ft tall holds about 6.3 cubic feet, roughly a quarter yard.
A poured 80 lb bag yields about 0.60 cubic feet, a 60 lb bag about 0.45. Divide the volume by the yield and round up. Bags make sense for small pours. Over about a yard? That is a lot of mixing, so we flag ready-mix instead.
We add about 10 percent on top. Grade is never dead flat, forms bow, and a little always spills. Running short with the truck on site is the expensive mistake, so the smart move is to order a hair over.
This is the free warm-up. PlumbCut reads your whole plan set and prices the entire job: walls, headers, sheathing, trusses, and the concrete too. The yardage is the easy part. Let the AI do the takeoff on your next real job and hand you a customer-ready bid.