Bags or a truck? Where ready-mix starts beating 80-lb bags

Every slab project hits the same fork: mix bags yourself or order a truck. The honest answer is a number, not a vibe — and it’s lower than most people think.

An 80-lb bag yields about 0.6 cu ft. A 10×10 pad at 4 inches needs 33.3 cu ft — that’s 56 bags, roughly 4,500 lb of material you’ll lift twice, and about 28 wheelbarrow trips of mixed concrete before any of it starts to set.

Under a cubic yard, bags win on price and flexibility. Past about 1.5 cu yd, the truck wins even with a short-load fee — and it wins on quality too, because one consistent pour beats 56 slightly different batches.

Three things tip the math further toward the truck: any slab thicker than 4 inches, any pour you can’t finish in two hours, and any site where the mixer sits more than 50 feet from the forms.