Concrete Volume & Ordering Calculators

Concrete volume and ordering is the part of a pour where an estimate becomes a purchase: the cubic yards, bags, cement, water and truck loads you must buy before the first shovel of concrete goes in. This page collects the free GeniesMag tools for that step, from a basic volume estimate to a pump budget, so you can decide how much to order and how to buy it.

Each calculator runs in your browser and shows its formula and sources. Pick the tool that matches your question, or read the ordering guide below.

Volume, Mix and Cost Calculators

These tools answer the planning questions: how much concrete, what goes into it, what it weighs and what it costs, including shotcrete and flowable backfill.

Bagged Concrete Calculators

Bagged concrete suits small jobs, awkward access and repairs. These tools count bags, batches and pallets, and help you decide when a delivery makes more sense.

How Concrete Ordering Works

Ordering is a chain of conversions. You start with a volume, turn it into bags or yards, choose how it arrives, and then plan how it gets into the forms. The volume formula lives on the concrete calculators main page, so this starts after you have a number.

Step 1: Convert volume to bags

Bags are sold by weight but filled by volume. For QUIKRETE Concrete Mix 1101, an 80 lb bag yields 0.60 cubic feet, a 60 lb bag yields 0.45 and a 40 lb bag yields 0.30. QUIKRETE Fast-Setting Concrete Mix yields about 0.375 cubic feet per 50 lb bag. Other brands differ. Divide your volume by the yield and round up.

Step 2: Decide between bags and ready-mix

Ready-mix arrives mixed and is priced by the cubic yard, but suppliers add fees for delivery and for small or part loads, and those fees vary by region and supplier. The bagged vs ready-mix calculator puts both totals side by side using your own prices.

Step 3: Plan trucks and pumping

For ready-mix, the number of loads depends on your volume and the load size your supplier uses, so confirm that with them. The concrete truck calculator rounds loads up and spaces them by how fast your crew can place concrete, so one load does not stiffen while the next waits. If a truck cannot reach the forms, a pump adds a setup charge plus time and per-yard fees.

A worked example

Say you are pouring a 12 by 20 foot slab, 4 inches thick, with 10 percent waste. The volume is 12 x 20 x (4 / 12) = 80 cubic feet. With waste that becomes 80 x 1.10 = 88 cubic feet, or 88 / 27 = 3.26 cubic yards.

In 80 lb bags, that is 88 / 0.60 = 146.7, so 147 bags, weighing 147 x 80 = 11,760 lb on the label. In 60 lb bags it is 88 / 0.45 = 195.6, so 196 bags. If your supplier stacks 80 lb bags 42 to a pallet, 147 bags is 3.5 pallets, so you buy 4. A mixer that handles about 3 bags a batch would need roughly 49 batches.

Mix ratios, cement and water

If you batch from raw materials instead of premixed bags, the concrete mix calculator splits the volume by a ratio such as 1:2:4 (cement : sand : gravel). It converts wet volume to dry volume with a factor of 1.54, because loose materials take more space than the finished concrete. For that same 88 cubic feet, the dry volume is 88 x 1.54 = 135.52 cubic feet, and cement is 135.52 / 7 = 19.4 cubic feet. The cement calculator treats one 94 lb Portland bag as about 1 cubic foot, so that is 20 bags after rounding up. Nominal ratios are rules of thumb for small, non-structural work; structural pours need a designed mix.

Water matters as much as cement. The water-cement ratio is the weight of water divided by the weight of cement: 300 lb of water on 600 lb of cement is 0.50. A lower ratio generally means stronger concrete, and the water cement ratio calculator gives an approximate 28-day strength from the ACI relationship.

Weight and coverage

Normal-weight concrete runs about 150 lb per cubic foot, so the 88 cubic feet above weighs roughly 13,200 lb, about 6.6 short tons. The concrete weight calculator checks it against a payload. To work backward from a quantity you already have, the concrete coverage calculator shows how far a yard or a stack of bags will go at a given thickness.

Specialty placements

Some placements need extra material. Shotcrete rebounds off the surface, and the American Shotcrete Association says rebound may be estimated at 5 to 15 percent, averaging about 10 percent, with ACI 506R citing total losses of 10 to 30 percent. The shotcrete calculator adds it. Flowable fill is a self-leveling backfill that can be delivered in ready-mix trucks, and ACI 229R defines it by a compressive strength of 1,200 psi or less. The flowable fill calculator sizes trenches and voids.

Common Mistakes

Judging bags by weight, not yield

An 80 lb bag fills only 0.60 cubic feet. Buying by weight alone, or assuming a pallet goes further than it does, leaves you short mid-pour.

Ignoring fixed costs on small orders

A small delivery, a part load or a pump can carry charges that do not shrink with the order. Compare totals, not yard prices.

Adding water to make it easier

Extra water eases placing but raises the water-cement ratio, which generally lowers strength. Add water only within the limits of your mix design.

Frequently Asked Questions

More Concrete Calculators

Once you know how much to order, move on to the shape you are pouring.

Ready to order? Start with the concrete calculator, then choose bags or ready-mix.