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Concrete Calculator — Cubic Yards, Bags & Truck Cost (2026)

Drop your slab, footing, column, stairs, or wall dimensions — get cubic yards needed, premix bag count (60-lb + 80-lb), ready-mix truck cost, and the honest verdict on premix-vs-truck for your pour size.

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Reviewed by CalcBold Editorial · Sources: ACI 318-19 + Portland Cement Association + RSMeans 2026 unit costs + Quikrete/Sakrete bag-yield specsLast verified Methodology

Concrete Calculator

Different pour types use different volume formulas. Slab/footing/wall = rectangular; column = cylindrical; stairs = triangle-wedge per step.

Used for slab, footing, and wall pours. Ignored for column / stairs / custom.

Used for slab, footing, and wall pours. For walls this is the wall thickness in feet.

Slab thickness in inches. Typical: 4" for residential floors, 6" for driveways, 8-12" for footings.

Column diameter in feet. Typical deck posts: 10-12" (~0.83-1.0 ft) · structural piers: 18-24" (1.5-2.0 ft).

Column height in feet. Set to your full hole depth + above-grade height.

Per-step riser height (typical 7"; code max usually 7.75").

Per-step tread depth (typical 11"; code min usually 10").

Width of each step in feet.

How many steps in the run.

Skip the geometry math — enter cubic yards directly if you already know the volume.

Standard 5-10% to cover spillage + overbuild + form irregularities. 10%+ for complex shapes (stairs, curved walls).

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How much concrete do I need? — short answer first

For a typical 20' × 10' patio slab at 4" thick, you need about 2.5 cubic yards (with 5% waste factor) — roughly 150 sixty-pound premix bags ($825 retail) or one ready-mix truck delivery at the minimum-load price (~$700-1,000 with delivery fee). Above 3 cubic yards, the truck wins on cost AND labor; below 1 cubic yard, premix bags win on flexibility. The calculator above runs your specific dimensions through the same ACI 318-19 formulas a structural engineer uses, then surfaces the premix-vs-truck breakeven for your exact volume.

What This Calculator Does

Drop your pour type (slab, footing, wall, column, stairs, or custom cubic-yard entry) and dimensions — get cubic yards needed, premix bag count (both 60-lb and 80-lb sizes), ready-mix truck cost at 2026 RSMeans benchmarks, and the verdict on whether premix or truck wins for your specific volume. The waste factor slider lets you tune the safety margin from 0% (perfect placement) to 15% (complex shapes or hard-to-access pours).

The Math / Formulas Used

These come straight from ACI 318-19 (the US structural-concrete design code) and Quikrete + Sakrete manufacturer specs. The cubic-yard-to-cubic-foot constant (27) is geometry — there are 27 cubic feet in a cubic yard because a yard is 3 feet on each side.

Premix bag yield is published by the manufacturer: a 60-lb bag of Quikrete or Sakrete makes 0.45 cubic feet of finished concrete; an 80-lb bag makes 0.60 cubic feet. The calculator rounds the bag count UP — you can’t buy a partial bag, and running out mid-pour means a cold-joint failure that structurally weakens the slab.

Ready-mix truck pricing benchmarks come from RSMeans 2026 Construction Cost Data — the industry-standard US construction-cost reference. Your local quote will vary ±30% by region, with HCOL markets (Bay Area, NYC metro, Honolulu) running 30-50% above the benchmark and LCOL markets (rural Midwest, parts of the South) 20-30% below.

How to Use This Calculator

  1. Pick pour type. Slab (floor/patio/driveway), footing, wall, column (round), stairs, or custom (skip the geometry and enter cubic yards directly).
  2. Enter dimensions. Slab/footing/wall: length × width × thickness. Column: diameter × height. Stairs: riser × tread × width × step count.
  3. Set waste factor. 5% for simple rectangular pours. 10% for complex shapes (stairs, curved walls). 15% for first-time DIY or hard-to-access pours where form spillage is likely.
  4. Read the verdict. Cubic yards needed (the primary number), premix bag count for both sizes, ready-mix truck cost, and the premix-vs-truck recommendation.
  5. Order accordingly. Below ~2 cu yd, buy premix at Home Depot or Lowe’s. Above 3 cu yd, call 2-3 local ready-mix suppliers for quotes — the calculator’s truck cost is a benchmark, not a quote.

Three Worked Examples

Example 1 — 20' × 10' patio slab at 4" thick

Cubic yards: (20 × 10 × 4) / 324 = 2.47 cu yd raw. Add 5% waste = 2.59 cu yd. That’s 155 sixty-pound bags ($853 retail) OR 3 cu yd truck delivery at $435 + $250 fee = $685 total. Truck wins by $168 AND saves a full day of mixing labor. Recommendation: ready-mix truck.

Example 2 — 4 footings, 24" diameter × 48" deep each

Per footing: π × 1² × 4 / 27 = 0.465 cu yd. Four footings = 1.86 cu yd. Add 10% waste (complex shape) = 2.05 cu yd. Premix: 123 sixty-pound bags ($677). Truck: 3 cu yd delivery ($685 with short-load fee). Recommendation: premix DIY— save $8 and avoid the truck’s rigid pour window. With 2 helpers, mix-and-pour in 4-5 hours.

Example 3 — 4' high × 30' long retaining wall, 8" thick

Cubic yards: (30 × 0.67 × 8) / 324 = 0.50 cu yd — but wait, that’s for the wall’s slab equivalent. Treating the wall as 30' long × 0.67' thick × 4' tall (8" equivalent = 0.67') and converting: 30 × 0.67 × 4 / 27 = 2.98 cu yd. Add 10% waste for forming complexity = 3.27 cu yd. Premix: 196 sixty-pound bags ($1,078). Truck: 4 cu yd delivery ($830). Recommendation: truck delivery, with rebar at #4 (1/2") 12-18" on-center per ACI 318-19. Permit required in most jurisdictions for walls 3-4 ft+ tall.

Common Mistakes

  • Ordering exact volume with no waste factor. Form spillage, mix inconsistency, and overbuild always add 3-10% to the actual volume placed. Running out mid-pour means a cold-joint failure that weakens the structure — you can’t “top up” the next day. Always add at least 5%.
  • Confusing inches with feet on thickness. A 4" slab is 0.333' thick — not 4'. The calculator’s thickness input is in inches; if you accidentally enter it in feet, the volume will be 12× what you need (and 12× the cost). Double-check.
  • Skipping rebar on structural pours. Slabs ≤ 4" on grade often skip rebar (wire mesh is adequate); slabs ≥ 4" or any structural load (driveway, footing, retaining wall) need #4 (1/2") rebar at 12-18" spacing per ACI 318-19. Rebar adds ~$30-60/cu yd but prevents the cracking failure at year 20-30.
  • Pouring without checking weather. Hot weather (>85°F) accelerates set to 30-45 minutes; pour at dawn and cover with damp burlap. Cold weather (<50°F) extends cure dramatically; below freezing damages the cure permanently. Plan around 7-day forecast.
  • Ordering premix at 4+ cu yd volume. Above 3 cubic yards, the labor of mixing 200+ bags solo (or with one helper) over 4-6 hours is brutal. The ~$200-400 you save on materials gets eaten by exhaustion + risk of inconsistent batches. Above 3 cu yd, almost always call a ready-mix truck.
  • Skipping the permit on a structural pour. Pouring footings, retaining walls >3-4 ft tall, or a structural slab without a permit means tear-out + re-pour + fines if inspected later. Permits run $75-500. Always call your local building department before pouring anything structural.

Methodology & Sources

Volume formulas: ACI 318-19 Building Code Requirements for Structural Concrete (American Concrete Institute) — the authoritative US structural-concrete design standard. Premix bag yields: Quikrete Concrete Mix product specifications (60-lb = 0.45 cu ft, 80-lb = 0.60 cu ft) — manufacturer-published. Ready-mix truck cost benchmarks: RSMeans 2026 Construction Cost Data — the industry-standard US construction-cost reference, updated annually. Pour-window timing: Portland Cement Association Concrete Basics 2026— set time at 70°F ambient is ~1 hour from water-added. Regional adjustment: actual local prices vary ±30% by metro; always call 2-3 ready-mix suppliers for live quotes above 3 cubic yards.

How to Read the Verdict

  1. Below 1 cu yd — premix wins on flexibility. Solo mixing in a wheelbarrow over 30-90 minutes is realistic. Premix gives you control over pour timing and lets you mix-and-place at your own pace. Truck delivery is overkill at this volume.
  2. 1-3 cu yd — judgment call. Premix saves $100-400 vs truck but you pay in 4-6 hours of mixing labor. If you have 1-2 helpers and a rental mixer ($45-75/day from Home Depot), premix is workable. If solo or on a tight schedule, truck wins. The calculator’s recommendation line picks based on cost alone — factor in your labor reality.
  3. 3-8 cu yd — truck wins decisively. Premix labor at this scale (200-500 bags) is punishing; mixing inconsistency becomes a real cold-joint risk. Call 2-3 local ready-mix suppliers; expect short-load fees on 3-4 cu yd orders that drop above 4-5 cu yd.
  4. Above 8 cu yd — multiple trucks, hard scheduling. One truck typically holds 8-10 cu yd. Larger pours need staggered truck arrivals (every 30-45 minutes) and a clear pour plan to avoid cold joints between truck loads. Hire a contractor for structural pours at this scale.
  5. Any volume + structural role — permit + rebar non-negotiable. Footings, retaining walls, slabs supporting buildings, columns — these need a permit, inspection, and ACI 318-19-compliant rebar. Skipping these is a tear-out-and-re-pour risk if inspected.

Planning the full project? After the concrete, the lumber calc handles framing on top, the roofing calc plans the matching cover overhead, and the deck cost calc sizes the full project if you’re pouring footings under a deck. Fence post-holes use concrete too — run the fence calc to get post count, then multiply by ~1.5 cu ft per post.

Sources & Methodology

The formulas, thresholds, and benchmarks behind this calculator are anchored to the primary sources below. Where a study or agency document is the underlying authority, we link straight to it — not a summary or republished version.

  1. American Concrete Institute — ACI 318-19 Building Code Requirements for Structural Concrete· American Concrete Institute

    Authoritative US structural-concrete design standard. Source of the volumetric formulas (cu_yd = L × W × T_in / 324 for rectangular; π · r² · h / 27 for cylindrical) and the minimum-thickness + rebar-spacing guidance referenced in the calculator's verdict logic.

    Accessed

  2. Portland Cement Association — Concrete Basics 2026· Portland Cement Association

    Industry primer on residential + commercial concrete practice — mix design, slump targets, finishing techniques, and the 1-hour set window at 70°F ambient referenced in the calculator's pour-planning notes.

    Accessed

  3. RSMeans — 2026 Construction Cost Data· Gordian / RSMeans

    The industry-standard US construction-cost reference, updated annually. Source of the $145/cu yd ready-mix base price + $250 delivery fee benchmarks used in the calculator's truck-cost compare. City-cost indexes published per major metro for regional adjustment.

    Accessed

  4. Quikrete — Concrete Mix Coverage Calculator + Product Specifications· Quikrete Companies

    Manufacturer-published bag yield data — 60-lb premix bag = 0.45 cu ft, 80-lb bag = 0.60 cu ft. These are the bag-count conversion constants used in the calculator's premix math.

    Accessed

Frequently Asked Questions

The most common questions we get about this calculator — each answer is kept under 60 words so you can scan.

  • How accurate is the concrete calculator?
    Within ±3% on cubic yards when dimensions are accurate — it uses ACI 318-19 volumetric formulas directly (cu yd = L × W × T_in / 324 for rectangular, π·r²·h/27 for cylindrical). The bag count assumes 0.45 cu ft yield per 60-lb premix bag (manufacturer specs from Quikrete + Sakrete); your actual bag count can vary ±2 bags due to mix consistency. Truck-cost ranges use 2026 RSMeans averages ($145/cu yd base + $250 delivery) — your local quote will be ±30% based on region, short-load fees, and pump-truck requirements.
  • How many bags of concrete in a cubic yard?
    A cubic yard = 27 cubic feet. A 60-lb premix bag yields 0.45 cu ft, so 1 cu yd ≈ 60 bags. An 80-lb bag yields 0.60 cu ft, so 1 cu yd ≈ 45 bags. The calculator rounds UP to whole bags. Practical limit for DIY premix: ~2 cu yd solo or with one helper. Above that, ready-mix truck delivery is faster + cheaper per cu yd.
  • When does ready-mix truck beat premix bags?
    Roughly above 3 cubic yards — at that point, 60-lb premix bags cost ~$1,000+ (180+ bags), the labor of mixing batches over 4-6 hours becomes brutal, and a 4-cu-yd truck delivery typically runs $830-1,000 with min-load fees. Below 1 cu yd, premix wins on flexibility (you mix at your own pace). The 1-3 cu yd range is a judgment call: premix saves cash but truck saves an entire pour day.
  • What's the standard concrete thickness for a slab?
    4" for residential interior slabs (basement floors, garage floors light-duty). 6" for driveways + heavy-load garages. 8-12" for footings. Patio slabs typically 4". Pool decks 4-6". Always check local code — frost depth in northern climates often dictates footing depth (e.g., 42-48" below grade in zones with deep ground frost). ACI 318-19 chapter 5 has the structural design tables.
  • How long do I have to work with concrete after mixing?
    Roughly 1 hour from water-added at ~70°F ambient. Hotter weather shortens it (45 min at 90°F+); colder weather extends it (90 min at 50°F). Ready-mix trucks add retarders for longer transit; DIY premix sets faster. Plan your pour: forms ready, screed bar and floats laid out, helpers in position, finishing tools cleaned, before the first bag is mixed.
  • Do I need rebar in my concrete pour?
    For slabs <4": often not (welded wire mesh adequate). For slabs ≥4" or any structural load (driveway, retaining wall, footings supporting walls): yes, #4 (1/2") rebar grid at 12-18" spacing per ACI 318-19. Rebar adds ~$30-60/cu yd to material cost but prevents the cracking failure mode at the 20-30 year mark. Vapor barrier (6-mil poly under slab on grade) is also standard.
  • What waste factor should I use?
    5% for simple rectangular pours with experienced placement. 10% for complex shapes (curved walls, stair risers, irregular footings). 15% for first-time DIY or hard-to-access pours where form spillage is likely. Going under 5% risks running out mid-pour, which is brutal — a partial pour can't be 'topped up' the next day without a cold joint that weakens the structure.
  • Should I rent a concrete mixer or hand-mix?
    Hand-mix (wheelbarrow + hoe) is fine up to ~0.5 cu yd / ~30 bags — beyond that, the labor is punishing. A rental electric mixer ($45-75/day from Home Depot) is the right tool for 0.5-2 cu yd. For 2+ cu yd, ready-mix truck delivery is almost always cheaper per cu yd once you account for mixer rental + 4-8 hours of labor. The calculator's verdict line flags this breakeven.
  • What's the minimum truck order for ready-mix concrete?
    Typically 1 cu yd in 2026 — but most suppliers charge a 'short-load fee' on orders under 3-5 cu yd ($75-250 fee). Below 1 cu yd, no truck will deliver. Between 1-3 cu yd, you're paying premium per cu yd to cover the truck's idle time. Above 3-4 cu yd, you hit the bulk rate (~$145/cu yd 2026 average; calculator uses this benchmark).
  • Do I need a permit for a concrete pour?
    Slab on grade <120 sq ft + no structural role: usually no. Driveway replacement (same footprint + thickness): often no. Footings for new construction, retaining wall >3-4 ft tall, structural slab supporting a building: yes — permit + inspection required in most US jurisdictions. Call your local building department before pouring; permits run $75-500 typical, inspection fee separate. Pouring without a required permit can mean tear-out + re-pour at your cost.
  • How long until I can walk on / drive on the concrete?
    Walk on lightly after 24 hours (set). Heavy walking + light load after 3 days. Drive on after 7 days (passenger car). Full 28-day cure for design strength (heavy load, structural use). Curing temperature matters — cold weather (<50°F) extends all these timeframes; below freezing damages the cure. Cover with plastic + keep damp for the first 3-7 days for strongest finish.
  • Why does the calculator show a 60-lb AND 80-lb bag count?
    Both sizes are sold; you pick by personal preference. 60-lb bags are easier to lift (single-person friendly) but you make more trips to the mixer. 80-lb bags are heavier but you handle 25% fewer bags total. Cost per cubic foot is usually slightly better on 80-lb bags. Both yield identical finished concrete — the difference is only ergonomics + total trip count.