Ordering short on a ready-mix pour is expensive twice over: a short-load fee for the first truck being under the supplier's minimum, and often another short-load fee for the emergency second truck. Here's how to get the order right the first time.
"About 10 by 10" isn't precise enough — measure to the nearest inch, especially thickness, since a half-inch difference in thickness across a large slab adds up to a meaningful volume difference.
5–10% on top of your raw calculated volume covers spillage, subgrade irregularity, and formwork imperfection. Skipping this is the single most common cause of a short pour.
Most suppliers deliver in quarter-yard or half-yard increments. If your buffered calculation lands at 4.6 yards, order 4.75, not 4.5.
Many suppliers charge a short-load fee under 3–4 cubic yards. If your project is close to that threshold, it's often worth combining it with another small pour (a footing, a post) to clear the minimum in one trip rather than paying the fee twice.
Run your numbers through the Concrete Calculator or the Square Footage Calculator before you call your supplier — both add the waste buffer automatically so the number you give them is the number you should actually order.