Free Concrete Calculator — Yards, Bags & Cost

Calculate concrete volume for slabs, footings, and columns. Get cubic yards, 60 lb and 80 lb bag counts, and estimated cost with a waste factor.

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Typical: 5–10% for slabs, 10–15% for complex shapes.

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What is this calculator for?

You're standing in your backyard staring at the patch where you want a 12 × 16 ft concrete patio. The Home Depot guy asked how many 80-pound bags you need and you have no idea. Or you're pouring a small footing for a fence post (about 8" diameter, 30" deep) and you need to know whether one 60-pound bag is enough or you need three. The concrete calculator gives you the bag count or cubic yards needed for your specific project, with the right thickness for the application.

Concrete is measured in cubic yards for trucked deliveries and 60- or 80-pound bags for small DIY projects. One cubic yard = 27 cubic feet. An 80-pound bag of mixed concrete makes about 0.6 cubic feet when mixed — so 45 bags equal 1 cubic yard. A 60-pound bag makes 0.45 cubic feet — 60 bags per cubic yard. For most DIY projects under 1 cubic yard total, bagged concrete is cost-effective and convenient. Above 1 cubic yard, ready-mix delivery (a concrete truck) is dramatically faster and often cheaper per yard despite the delivery fee.

This calculator takes your project dimensions (length, width, thickness — or for round footings, diameter and depth) and computes cubic yards needed plus 60-lb and 80-lb bag equivalents. It also adds standard waste factor and suggests ready-mix delivery vs bagged based on project size.

How to use this calculator

Enter your project type: slab (patio, driveway, walkway), footing or pier (column or post base), tube footing (round form), or staircase. Each has standard thickness guidelines and the calculator applies them.

For slabs: enter length × width in feet. Standard thicknesses: 4 inches for sidewalks, patios, residential driveways (light vehicles). 5-6 inches for driveways with heavier vehicles (trucks, RVs). 6-8 inches for shop or garage floors with heavy loads. Pool decks: 4 inches. Add 0.5-1 inch if the area will see freeze-thaw cycles (cold climate requires deeper coverage to prevent cracking).

For footings: enter the dimensions. Square footings: length × width × depth. Round footings (tube forms): diameter × depth. Standard fence-post footing: 8-12 inch diameter, 24-36 inches deep (must extend below frost line — varies by climate). Deck footings: 12-16 inches diameter, 36-48 inches deep typical. Standard residential foundation footings: 8 × 16 inches × full perimeter length.

Set your climate (frost line depth). Northern US (MN, ND, ME): 48"+ frost line. Mid-Atlantic and Midwest: 30-42". Southern US: 12-18". Florida and Gulf Coast: 0-12". Footings should extend below frost line to prevent heaving. Slabs in cold climates often have thicker edges (10-12") even with 4" interior thickness, with rebar reinforcement.

The calculator outputs cubic yards, 60-pound bag count, 80-pound bag count, and recommends bagged-or-truck based on total volume.

Understanding your results

The calculator returns cubic yards of concrete needed, equivalent counts in 60-lb bags and 80-lb bags, plus a cost estimate at typical bagged-concrete prices ($5-8 per 80-lb bag) and ready-mix prices ($150-200 per cubic yard delivered).

The bagged-vs-truck threshold. For projects under 0.5 cubic yards (about 22 of 80-lb bags), bagged is clearly the right choice — no minimum order to worry about, mix as you go. For 0.5 to 1 cubic yard, you're in the gray zone — bagged is fine if you have help or several days to spread the work; truck delivery is faster but adds $80-150 minimum-order/delivery fees. For 1 cubic yard or more, ready-mix delivery is generally faster, cheaper per yard, and produces more consistent results. A typical residential ready-mix truck carries 9-10 cubic yards, but they'll deliver as little as 1 yard for an extra fee (called "short-load fee," typically $50-100 per yard short).

The cost reality. A 12 × 16 × 4" patio = 192 sq ft × 0.333 ft thick = 64 cubic feet = 2.37 cubic yards. At 45 80-lb bags per yard with 10% waste: about 117 bags. At $6/bag: $702 in concrete plus mixing labor (mixing yourself with a wheelbarrow and shovel takes 4-6 hours; renting a mixer for $50-75/day cuts to 2-3 hours). Ready-mix delivery of 2.5 yards: $400-500 in concrete plus $100-150 short-load fee = $500-650. The truck wins on cost AND it pours in 10 minutes, with the concrete in better condition (mixed by truck, not by you in batches that set at slightly different times). For anything above 1.5 cubic yards, get the truck quoted before assuming bagged.

Frost line and footing depth. A fence post at 24" depth in Minnesota will heave with frost every winter and your fence will be crooked within 2-3 years. A fence post at 48" depth (below the Minnesota frost line) stays plumb. The calculator's footing depth recommendation reflects your climate; don't shortcut the depth to save concrete. Bag savings of 1 extra 80-lb bag ($6-8) versus the cost of replacing a heaved fence post (8-12 hours of work plus replacement materials) is a clear win for going deeper.

Reinforcement. For slabs, the calculator can recommend rebar or wire mesh based on size and use. 4-inch sidewalks with light foot traffic: no reinforcement needed. 4-inch patios: optional but recommended (wire mesh or fiber mesh in the mix). 5-6-inch driveways: rebar grid (#3 or #4 rebar at 16-24" spacing) standard. Garage and shop floors: rebar grid required.

A worked example

Daniel is building a 14 × 18 ft concrete patio behind his suburban Indianapolis house. He wants 4 inches thick for foot traffic. He'll be mixing himself with a rented mixer over a long weekend.

Math: 14 × 18 = 252 sq ft. Thickness 4 inches = 0.333 ft. Volume: 252 × 0.333 = 83.92 cubic feet = 3.11 cubic yards. With 10% waste: 3.42 cubic yards.

Bagged option: 3.42 × 45 80-lb bags/yard = 154 bags. At $6/bag: $924. Plus rented mixer ($75 for a weekend) plus rebar grid ($90 for #3 rebar at 18" centers) plus form lumber ($55) plus wire mesh + fiber additives ($35). Total materials: $1,180. Time to mix and pour by himself: 14-18 hours over two days. Quality risk: batches mixed over 16 hours don't fully match — visible color differences possible between Saturday morning and Sunday afternoon pours.

Ready-mix option: 3.5 yards delivered. Quote: $185/yard × 3.5 = $648 plus $75 short-load fee (under 4 yards) = $723. Plus rebar + forms + fiber: $180. Total materials: $903. Time: forms on Saturday morning, truck arrives Saturday afternoon, pour in 15 minutes, finish in 2-3 hours (troweling, edging, control joints). Total: 6-8 hours including form work. Quality: consistent, professional-grade concrete from a single batch.

The truck wins on cost ($277 cheaper), time (8 hours vs 16+ hours of mixing), and quality. The bagged option only wins if Daniel can't get truck access to his backyard (some setbacks or fences prevent truck reach), or if he wants to spread the work across multiple weekends. For most 200+ sq ft slabs, the truck is the right answer.

Variation: Daniel decides to add a 4-foot deep frost-line column for a future patio cover. Tube form: 12" diameter × 48" deep = π × 0.5² × 4 = 3.14 cubic feet = 0.12 cubic yards. Bagged: 6 80-lb bags ($42). Trivially small; bagged is the obvious answer for any single footing under 0.3 yards.

Related resources

For other material-quantity calculations, see Paint Calculator, Flooring Calculator, Mulch Calculator, and Fence Calculator. For square footage of irregular slab shapes, the Square Footage Calculator. For broader renovation budget planning, the Savings Goal Calculator. The American Concrete Institute publishes ACI 318 (Building Code Requirements for Structural Concrete), the authoritative reference for residential and commercial concrete construction.

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Frequently asked questions

How much does a yard of concrete cost?

Ready-mix concrete delivered runs about $120–$180 per cubic yard in 2026, with most US markets near $150. Short-load fees (typically $80–$150) apply to orders under 5 cubic yards. Bagged concrete from a home center costs more per yard but is the only practical option for jobs under about half a yard.

How thick should a concrete driveway be?

4 inches is standard for residential driveways with normal car traffic. Thicken to 5–6 inches if you'll regularly park a heavy truck, RV, or boat. The subgrade matters as much as thickness — compacted gravel base, proper drainage, and reinforcement (rebar or wire mesh) keep concrete from cracking far better than extra thickness alone.

Bags or ready-mix?

Ready-mix delivered makes sense above about 0.5 cubic yards (about 28 80-lb bags). For small footings, post holes, or repair work, bags are cheaper and more flexible. Mixing bags by hand is slow and tiring — for anything over 10 bags, rent a small mixer.

How long does concrete take to cure?

Concrete reaches roughly 70% of its strength in 7 days and 99% in 28 days. You can typically walk on it at 24 hours, drive a car on it at 7 days, and put it under full load (truck, RV) at 28 days. Curing in dry, hot, or freezing conditions requires extra care — keep the surface moist for the first week.

Can I pour concrete in cold weather?

Yes, but with precautions. Below about 40°F, fresh concrete cures more slowly and is at risk of freezing before it gains strength. Use a cold-weather admixture, warm water in the mix, and insulating blankets over the surface for 24–48 hours. Never pour onto frozen ground.

How thick should my concrete slab be?

Depends on use. Sidewalks and walkways: 4 inches. Residential patios (foot traffic only): 4 inches. Driveways for passenger vehicles: 4-5 inches. Driveways for trucks or heavy vehicles: 5-6 inches. Garage floors: 4-6 inches (some shops 6-8 inches). Pool decks: 4 inches. Concrete shed or workshop floor (light to moderate equipment): 4-5 inches. Industrial floor (heavy equipment): 6-8+ inches. Add 1 inch if you're in a cold climate (freeze-thaw cycles), or design the edge thicker (10-12 inches) with a 4-inch interior. Skimping below these minimums leads to cracking; going thicker than spec is mostly wasted concrete unless you have specific structural needs.

When should I use rebar versus wire mesh in concrete?

Rebar (steel reinforcing bar): used in load-bearing slabs, foundation footings, retaining walls, structural elements. Provides tensile strength concrete lacks. Standard residential rebar grid: #3 (3/8 inch) or #4 (1/2 inch) rebar at 16-24 inch centers, supported off the ground so it sits in the middle of the slab thickness. Wire mesh (welded wire fabric): used in lighter-duty slabs like sidewalks and patios. Cheaper and easier than rebar but provides less tensile reinforcement. Many residential patios use either wire mesh or fiber mesh additive (synthetic fibers mixed into wet concrete) for crack control. For driveways: rebar is the standard. For most patios under 200 sq ft: wire mesh or fiber additive is acceptable.

How long does concrete take to cure?

Initial set (concrete is hard enough to walk on): 24-48 hours depending on temperature. Light use (foot traffic, light furniture): 72 hours. Vehicle traffic on driveway: 7 days. Full design strength (3,000-4,000 PSI typical residential): 28 days. The 28-day cure is the engineering reference but concrete continues gaining strength for months. During the first 7 days, keep concrete moist (mist with water, cover with plastic) — drying too fast causes surface cracking and weakens the slab. Hot weather (80°F+) and dry conditions are the worst combinations for curing. Cold weather (below 40°F) slows the chemical reaction and may require insulating blankets or accelerator additives to set properly.

Should I hire a concrete contractor or do it myself?

DIY breakeven: projects under 200 sq ft and under $1,000 in materials are reasonable DIY. Above that, contractors are often cost-effective due to truck access, finishing skill, and quality of result. A poorly-finished concrete pour (uneven, bird-bathy, cracks, lippage at joints) is highly visible and bothers homeowners for years. Contractor cost for typical residential slab: $5-9/sq ft installed including materials, labor, and removal of existing surfaces. DIY materials only: $2-4/sq ft. Labor savings: $3-6/sq ft. Time investment: 8-16 hours per 200 sq ft for novice DIYer. Effective hourly: $40-100. For first-time concrete DIY, start with a small footing or a 4x4 stepping-stone pad before committing to a full patio.

What's the difference between concrete and cement?

Cement is the binding agent. Concrete is the finished product: cement + sand + gravel + water. People use the terms interchangeably but they aren't the same. A 'cement truck' is technically a concrete truck — the cement is one ingredient in the concrete it's delivering. Bagged 'concrete mix' (Quikrete, Sakrete, etc.) contains all the dry ingredients pre-mixed — just add water. Bagged 'cement' (Portland cement specifically) is just the binder; you'd add sand and gravel separately. For 99% of DIY projects, you want pre-mixed concrete bags, not bags of plain Portland cement.

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