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Concrete Calculator

Calculate concrete volume, weight and cost for any slab, footing or wall. Supports cubic yards, bags and ready-mix. Enter dimensions, select units and add waste to get instant, supplier-ready numbers.

1. Measurements & Dimensions

2. Material Properties & Waste Allowance

3. Optional Material Cost

CONCRETE CALCULATOR ESTIMATE
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Enter dimensions above to calculate

Calculation Breakdown & StepsFormula: V = length × width × thickness × identical sections
  1. Enter values to see step-by-step substitution.

    Engineering Assumptions:

    • Rectangular sections of uniform thickness. Split irregular shapes into non-overlapping rectangles.
    • Thickness and reinforcement must come from project plans; volume alone does not establish load capacity.
    VISUAL GUIDE — CONCRETE CALCULATORconcrete · concrete-calculator

    4K VISUAL GUIDE — PHOTOREALISTIC PREMIUM

    Concrete Calculator photorealistic 4K — TOP VIEW Length 12ft × Width 8ft =96 ft², SECTION Depth 6in, modern house with concrete slab formwork, woman with tablet showing Visual Guide

    Photorealistic 4K — Your requested 2(3).png upscaled to 3840×2160 — Length 12ft × Width 8ft =96 ft² @6in • Section 6in

    HOW IT WORKS — 3 SIMPLE STEPS (ORIGINAL 4K)

    Understanding Your Concrete Calculator — 3 simple steps: 1 Measure & Input your project size, 2 Automatic calculation of volume needed, 3 Get precise quantities for ordering

    Your original — Measure → Automatic Volume → Order Bags/Truck — 4K upscaled, 846KB JPEG

    Concrete Calculator — V = length × width × thickness × identical sections · example 12×8 @6in = 48.0 ft³ (1.78 yd³) → 1.96 yd³ with 10% waste · concrete-calculator

    What Is This Calculator?

    The Concrete Calculator — Estimates concrete volume, weight and ready-mix versus bag count for US slabs, footings and walls.

    What Does It Calculate?

    • Concrete volume in cubic yards and cubic feet
    • Ready-mix loads vs 40/60/80-lb bags
    • Weight and cost with waste

    How to Use the Calculator

    1. Measure Concrete 20 ft x 10 ft x 4 in — use feet for length/width and inches for thickness where typical.
    2. Enter values and select units. The calculator converts to feet before calculating (inches /12, yards x3).
    3. Adjust waste % and optional price, then click Calculate. Results show with waste included.
    4. Use Reset to clear and try another size.

    Formula & Engineering Methodology

    V = length × width × thickness × identical sections

    • L — Length for Concrete in feet
    • W — Width for Concrete in feet
    • D — Depth for Concrete in feet

    All units convert to exact standard engineering dimensions (NIST SP 811) before calculation to ensure consistency between US Customary and Metric measurements.

    Worked Example

    Example: Concrete 20 ft x 10 ft x 4 in

    STEPVALUE
    Convert depth4 in /12 = 0.333 ft
    Cubic feet20 x 10 x 0.333 = 66.67 ft3
    Cubic yards66.67 /27 = 2.47 yd3
    With 10% waste2.72 yd3

    Construction Information

    Material: Concrete — 4000 psi typical for driveways, 3000 psi for patios. Ordered by cubic yard (27 ft³) or bags (0.60 ft³ per 80-lb). Keep slump 4 in for slabs.

    • Measure longest x widest; split L-shapes into two rectangles and add.
    • Compact subgrade — soft spots add thickness.
    • For structural sizing (beams, headers, rebar) verify with a professional per local code.

    Material Information

    Concrete — 4000 psi typical for driveways, 3000 psi for patios. Ordered by cubic yard (27 ft³) or bags (0.60 ft³ per 80-lb). Keep slump 4 in for slabs.

    Waste & Overages

    Add 5–10% for spillage and uneven subgrade — 10% is safe for hand-screeded forms.

    Practical Tips

    • Order ready-mix over ~1 yd³ (45 bags) — faster and cheaper
    • Keep subgrade compacted and forms braced
    • Add one extra bag per 10 as buffer

    Common Mistakes

    • Forgetting to convert inches to feet (4 in = 0.333 ft)
    • Ordering the theoretical minimum — second trip costs more than 10% waste

    Assumptions & Engineering References

    • Rectangular sections of uniform thickness. Split irregular shapes into non-overlapping rectangles.
    • Thickness and reinforcement must come from project plans; volume alone does not establish load capacity.

    This calculator provides an estimate based on your inputs. Actual requirements vary by site, material and installation. For code-regulated or load-bearing work, consult a qualified professional.

    Calculations run 100% in your browser — zero tracking of your dimensions or input data.

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    Frequently asked questions

    What does the Concrete Calculator calculate?

    The Concrete Calculator estimates concrete quantity for US jobs — Concrete volume in cubic yards and cubic feet, Ready-mix loads vs 40/60/80-lb bags, Weight and cost with waste. Enter dimensions, choose units, add waste and price to get instant results.

    How do I measure for concrete?

    Measure concrete 20 ft x 10 ft x 4 in on site. Use the unit selectors — the tool converts inches→feet (÷12) and yards→feet (×3) before math. For non-rectangular, split into rectangles and add.

    How much waste should I add?

    Add 5–10% for spillage and uneven subgrade — 10% is safe for hand-screeded forms.

    How accurate is this concrete estimate?

    Math is exact for your inputs. Actual needs vary by site, material and installation. Add 5–10% waste for rectangular, 10–15% for irregular.

    About Calculator Street

    Built by Vipul Otari for US homeowners & contractors. Calculator inputs are processed in your browser. Estimates depend on your measurements, product specifications and the assumptions shown on this page. Confirm order quantities with your supplier and structural requirements with your project designer. Page updated: 2026-09-11.

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