Yards of Concrete Calculator

How to use this calculator

1. Pick what you are pouring. Slab covers pads, patios, driveways, and garage floors. Footing is the continuous strip or thickened edge under a wall. Round pad is a hot tub base or fire pit. Column is a pier or post hole. Stairs is a set of solid steps poured on grade.
2. Enter the dimensions in the units the trade uses. Slab footprint in feet, thickness in inches. Footing length in feet, width and depth in inches, because that is how a footing gets specced on a plan. Piers by diameter in inches and depth in feet.
3. Set the quantity. Six identical piers is one part with a quantity of six, not six parts.
4. Add the rest of the pour. This is the step every other calculator makes you do on paper. A patio with a thickened edge and three steps is three parts, one order, one truck.
5. Set the waste factor. Ten percent is the default because subgrade is never as flat as the plan. Drop it to five on a clean form over compacted base; push it higher if you are pouring on dug earth.
6. Read the method banner. It tells you whether this is a bag job, short-load territory, or a full truck, and what each route actually costs you in effort.
7. Take the order sheet with you. The PDF prints the part-by-part breakdown, the yardage, all four bag counts, and the haul weight so you can hand it to the plant or the lumber-yard counter.

Why this concrete calculator is different

We ran the same job through every calculator ranking on page one for this term. Here is what is typical, and what this one adds.

• Most of them only do one shape at a time. The big reference calculators give you separate boxes for a slab, a footing, and a set of stairs, and no way to total them. So you run it three times and add the numbers on the back of an envelope, which is exactly where ordering mistakes come from. This tool sums up to six parts of mixed shapes into a single order.
• None of them rounds to what a plant actually sells. Ready-mix is billed in quarter-yard increments. A raw answer of 5.43 yards is not an order. This tool gives you the number you say on the phone.
• None of them tells you which route you are on. Under a yard is a bag job. Between one and roughly four yards you are in short-load territory and will pay a surcharge. Past that you are booking trucks. That single decision changes your whole weekend, and no calculator on page one surfaces it.
• None of them checks whether you can carry it. A pallet of eighty-pound bags weighs more than most half-ton pickups are rated to haul. This tool converts the bag count into pallets, total weight, and how many trips that actually is.
• Bag counts here cover all four sizes. Most results give you eighty-pound bags and stop, which is no help when the store is out of eighties and has a wall of sixties.
• Nobody offers an embed. If you run a DIY blog, a masonry supply site, a builder forum, or a shop class, the iframe at the bottom of this page puts the same calculator on your site with attribution built in. Free.

How it works (the math behind the numbers)

Every shape resolves to cubic feet, the parts get summed, and the total converts once at the end. Doing the conversion once instead of per shape is what keeps a multi-part pour from drifting a few hundredths of a yard.

Per part (cubic feet):
  slab       L(ft) × W(ft) × T(in)/12 × qty
  footing    L(ft) × W(in)/12 × D(in)/12 × qty
  round pad  π × (dia(in)/24)² × T(in)/12 × qty
  column     π × (dia(in)/24)² × H(ft) × qty
  stairs     W(ft) × [ run×rise×n(n+1)/2 + landing×n×rise ] / 144

Project total:
  with_waste   = Σ parts × (1 + waste%)
  cubic_yards  = with_waste / 27
  order_yards  = ceil(cubic_yards / 0.25) × 0.25
  bags         = ceil(with_waste / bag_yield)
  weight_lb    = with_waste × 150
  trucks       = ceil(order_yards / 10)

The stair formula treats the steps as a solid mass poured on grade. Each step sits one rise taller than the one in front of it, so the cross-section is the sum of n rectangles stepping up by one rise each, which collapses to run times rise times n(n+1)/2. A landing adds a full-height block behind the top step. If your steps are formed hollow over fill, you will use less than this says.

Bag yields come from the Quikrete Concrete Mix spec data: a 40 lb bag makes 0.30 cubic feet, 50 lb makes 0.375, 60 lb makes 0.45, and 80 lb makes 0.60. Sakrete and most store-brand 4,000 psi mixes publish the same numbers. Check the bag you actually buy, because crack-resistant and fast-setting mixes yield slightly differently.

Weight uses 150 pounds per cubic foot, the Portland Cement Association figure for normal-weight mix, which works out to about 4,050 pounds per cubic yard. Note that dry bags weigh less than the finished concrete: fifty-six eighty-pound bags is 4,480 pounds on the pallet but roughly 5,000 pounds once you add the water.

Cross-checked against published answers. A ten-by-ten slab at four inches comes out at 1.23 cubic yards and fifty-six eighty-pound bags here, against the 1.24 yards and fifty-six bags that Concrete Network publishes. At six inches both give 1.85 yards and eighty-four bags. The old contractor rule of thumb agrees too: square feet divided by 81 is your yardage at four inches thick, because 27 divided by one-third of a foot is exactly 81. Every fixture in sites/diy/src/data/tools/yards-of-concrete-calculator/fixtures.json runs before each deploy, so if the math ever drifts the build fails instead of the page going out wrong.

Three real pours

Ten by twelve shed slab at four inches

The most common concrete job a homeowner ever does. One hundred twenty square feet at four inches is 40 cubic feet, which is 1.48 cubic yards before waste and 1.63 after ten percent. You order 1.75 yards. That is short-load territory: seventy-four eighty-pound bags is a genuinely miserable day with a mixer, and the surcharge on a small delivery is usually cheaper than the day you spend. If you do go the bag route, that is two pallets and about four trips in a half-ton pickup.

Six deck piers, twelve inch tubes, four feet deep

Each pier is 3.14 cubic feet, so six is 18.85 and ten percent waste puts you at 20.73 cubic feet, or 0.77 of a yard. Under the one-yard line, so this is a bag job: thirty-five eighty-pound bags or forty-seven sixty-pounders, one pallet, about two pickup trips. Most plants will not send a truck for three-quarters of a yard without charging you for a full one. For the tube sizes, rebar schedule, and frost-depth check on a footing job like this, use the dedicated Sonotube calculator instead, which adds the pieces this general calculator does not track.

Twenty by twelve patio, two twenty-foot footings, three steps

This is the pour that breaks every other calculator. The slab is 80 cubic feet, the two twelve-by-twelve-inch footings add 40, and three steps at seven by eleven inches, four feet wide, add another 12.8. Total 132.8 cubic feet, or 146.1 with ten percent waste, which is 5.41 cubic yards. You order 5.5 and it fits in one truck. Run those three parts through separate calculators and it is very easy to lose the steps, show up half a yard short, and finish the last section with bagged mix that never quite matches the color.

What changes the number after you order

• Subgrade. An inch of sag across a twenty-by-twenty slab is another third of a yard of concrete you did not plan for. Compact and screed the base, then check it with a string line before the truck is on the way.
• Form spring. Wet concrete pushes hard. Forms that bow out an inch in the middle of a long wall silently add volume, and the fix is stakes every two feet, not hope.
• Thickened edges you forgot to enter. Most slabs on grade are thicker at the perimeter. Add that as a footing part rather than rounding the whole slab up.
• Over-dig on footings. A trench dug by hand is never the width on the plan. If your trench walls are ragged, budget waste at the top of the range.
• Weather. Below about forty degrees or above ninety, concrete does not behave. Cold slows the set and needs blankets, heat flashes the surface and needs a retarder and shade. The first twenty-four hours set the strength you keep.
• What the plant will actually deliver. Minimum orders, short-load fees, Saturday rates, and how far the chute reaches all vary by supplier. Call before you form, not after.

For the tools that do the work: a brushless cordless drill with a paddle is what makes the bag route survivable, and a decent pair of work gloves is not optional, because wet mix is caustic and will chemically burn skin it sits against for an afternoon. Most pours are nowhere near an outlet, so a portable generator runs the mixer, the vibrator, and the lights. Cement dust kills household vacuums, so cleanup is shop vac work. If you are assembling a kit from scratch, start with the essential tools every new homeowner needs.

Frequently asked questions

How do you calculate yards of concrete?

Multiply length by width by thickness to get cubic feet, then divide by 27, since a cubic yard is three feet cubed. Keep the units straight: footprint in feet, thickness in inches divided by twelve. The shortcut contractors use for a four-inch slab is square footage divided by 81, which is the same math with the thickness already folded in. At six inches, divide square footage by 54 instead. Then add five to ten percent for waste and round up to the nearest quarter yard, because that is the increment plants bill in.

How many yards of concrete for a 24x24 slab 4 inches thick?

A twenty-four by twenty-four foot slab is 576 square feet. At four inches that is 192 cubic feet, or 7.11 cubic yards in the ground. With ten percent waste you are at 7.82, so you order 8 cubic yards. That is one truck, about 32,000 pounds of concrete, and firmly past the point where bagged mix makes any sense: it would take roughly 352 eighty-pound bags.

How many yards of concrete for a 30x30 slab 4 inches thick?

Nine hundred square feet at four inches is 300 cubic feet, which is 11.11 cubic yards. Add ten percent waste and you order 12.25 cubic yards. A standard drum holds about ten yards, so plan on two loads and get them scheduled back to back. A slab this size also usually wants control joints and reinforcement, which are code items in most jurisdictions, so check before you form.

How many yards of concrete are in a truck?

A standard US ready-mix drum is rated for about ten cubic yards, and most plants load eight to nine on a normal delivery so the truck stays legal on weight. Anything under about a yard, plants generally will not deliver without charging you for a full one, and between one and four yards you should expect a short-load fee. This calculator flags which of those three brackets you are in as soon as you have entered enough of the pour.

Can I embed this concrete calculator on my site?

Yes. Copy the iframe snippet at the bottom of this page. The embedded version is stripped down for DIY blogs, masonry and hardscape supply sites, builder forums, contractor sites, and shop classes. Attribution is built into the snippet. Free, no signup, no analytics attached to the embed.

Related tools

• Sonotube Calculator: tube count, rebar schedule, and a frost-depth check for a pier or footing pour
• Retaining Wall Calculator: blocks, caps, base aggregate, drainage stone, and adhesive for a segmental wall
• Brick Calculator: brick and mortar bag counts by bond pattern, with openings subtracted
• Fence Calculator: posts, rails, pickets, and the concrete bags to set them
• Browse all free tools by Jake →

Recommended tools for a concrete pour

• Best Cordless Drills: with a paddle attachment, a brushless 18V drill turns an eighty-pound bag in about ninety seconds. The entire bag route depends on this one tool.
• Best Work Gloves: wet concrete is caustic. Gloves are the difference between a finished pour and a week of chemical burns on your forearms.
• Best Portable Generators: mixer, vibrator, chargers, and work lights, on a site with no power.
• Best Shop Vacs: form and subgrade cleanup before the pour, bag dust after. Portland cement destroys household vacuums.
• Best Pressure Washers: tools, wheelbarrow, and chute pad have to be clean before the concrete goes off on them.
• Essential Tools for New Homeowners: the starter kit Jake recommends before any concrete or hardscape project.

Sources & methodology

• Quikrete Concrete Mix spec data: published bag yields: 40 lb = 0.30 cu ft, 50 lb = 0.375, 60 lb = 0.45, 80 lb = 0.60.
• Portland Cement Association: normal-weight concrete density, 150 lb per cubic foot (about 4,050 lb per cubic yard).
• Concrete Network, how much concrete do I need: the published 10 × 10 slab figures this calculator is cross-validated against.
• 2024 IRC, Chapter 4 (Foundations): footing depth, thickness, and frost-protection requirements that govern what you are allowed to pour.

Reviewed annually for source currency. About Jake · Last reviewed August 27, 2026.

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Free for DIY and home-improvement blogs, masonry and hardscape suppliers, builder forums, contractor sites, and shop classes. Attribution is included in the snippet. No fee, no account, no analytics attached to the embed.

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