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Stop guessing your pours. Calculate exact volume for slabs and holes, apply professional waste factors, and figure out whether to buy bags or order a truck. This free online tool allows you to calculate concrete yardage quickly and accurately. No sign-up or installation required.
Concrete is unforgiving. Unlike wood that can be cut, or paint that can be saved for later, concrete cures in a matter of hours. If you order too much, you pay exorbitant dumping fees. If you order too little, you ruin your slab by creating a "cold joint" while waiting for a second delivery.
Whether you are pouring a massive driveway slab or simply setting a few fence posts, accurate volume calculation is the single most critical step in masonry. This guide breaks down the complex dimensional math into simple, actionable steps used by professional masons.
The reason concrete math is confusing for DIYers is because it requires converting between three different dimensional units simultaneously.
You measure your yard in Feet. You measure the thickness of the wood forms in Inches. But the ready-mix company sells the material in Cubic Yards.
Our calculator handles all of this cross-dimensional math instantly. You simply input feet and inches directly, and the calculator yields exact cubic yardage (or cubic meters, if you are using the Metric system).
If you decide to mix bags yourself, do not make the mistake of looking at the weight. You aren't buying weight, you are buying yield. A standard 80 lb bag of concrete yields exactly 0.6 cubic feet of mixed material. It takes 45 of these bags to make a single cubic yard. Mixing 45 bags by hand in a wheelbarrow requires moving over 3,600 lbs of raw powder and hundreds of gallons of water. Know your physical limits before choosing bags over a delivery truck.
Mathematical volume and real-world volume are not the same thing. In a calculator, a 4-inch deep slab is perfectly 4 inches deep everywhere. In the real world:
Because of these factors, you must always order 10% more concrete than the exact mathematical volume. If you are pouring on very uneven ground, or if you are digging cylindrical holes with a manual post-hole digger (which makes very messy, un-uniform holes), you should increase your waste factor to 15%.
When using our built-in Budget Estimator to price out a truck delivery, remember that ready-mix companies often charge a "short load fee" if you order less than their minimum capacity (usually 3 or 4 yards). Always call your local plant to ask for their minimums. If you only need 1.5 yards, the short load fee might make the delivery cost nearly as much as a full 3-yard truck.
Common questions about concrete volume, mixing bags, and truck deliveries.