Concrete Wall Calculator
Estimate concrete for a poured wall from length, height, and thickness, with door and window openings excluded.
Content updated September 14, 2026
Rectangular-volume estimate for a solid poured wall only. Does not model rebar, formwork, footings, keyways, or waterproofing. Wall thickness and reinforcement are structural and code decisions — verify with a qualified professional.
Estimate the concrete volume for one or more equal poured walls — such as a foundation wall — from length, height, and thickness, with any door or window openings subtracted before the volume is calculated.
Openings are entered as area and converted to a volume using the wall thickness, then removed from the gross volume — the same opening-exclusion idea the paint and drywall calculators use for a flat surface, applied here to a volume instead.
The Concrete Wall formula
Gross volume = length × height × thickness × wall count · openings volume = openings area × thickness · net volume = gross volume − openings volume · order volume = net volume × (1 + allowance% ÷ 100)Length and height share one unit; thickness uses its own unit and is converted before multiplication · 1 yd³ = 27 ft³ exactly.
Worked example
A single 20 ft long, 8 ft high, 8 in thick wall with no openings has a gross and net volume of about 106.667 ft³. With a 10% allowance the order volume is about 117.333 ft³ (4.346 yd³); at 0.6 ft³ per bag that is 195.556 bags, rounding up to 196.
Assumptions, rounding, and limitations
Assumptions
- Each wall is a uniform rectangular prism of constant thickness.
- All walls entered are equal in length, height, and thickness; different sizes must be calculated separately and added together.
- Openings are entered as a single combined area and are assumed to pass fully through the wall thickness.
- The entered contingency percentage is applied to net (post-opening) volume.
Rounding: Volume math retains floating-point precision. Displayed volumes show up to three decimal places; the purchase-oriented bag result always rounds the exact quotient upward to a whole bag.
Limitations
- Does not model reinforcement, formwork, footings, keyways, waterproofing, or a tapered (battered) profile.
- Does not determine wall thickness or reinforcement — those are structural and local-code decisions.
- The result is a planning estimate and should be checked against approved drawings and field measurements.
Sources
- CIP 31 — Ordering Ready Mixed Concrete — National Ready Mixed Concrete Association
- NIST Guide to the SI, Appendix B: Conversion Factors — National Institute of Standards and Technology
Gross volume, then openings removed
Gross volume is length × height × thickness for one wall, multiplied by the number of equal walls. Each opening's area is multiplied by the wall thickness to get the volume of concrete it displaces, and the total openings volume is subtracted from gross volume before the contingency allowance is applied.
NRMCA's 4%–10% contingency guidance for ready-mix orders applies here too; the default allowance is 10% but stays editable for a project-specific decision.
What this does and does not model
This is a solid, uniform-thickness wall only. It does not model reinforcement, formwork, footings, keyways, waterproofing, or a battered (tapered) profile — for a tapered retaining wall, use the retaining wall calculator instead.
Frequently asked questions
▶How do I calculate concrete for a wall?
Multiply length × height × thickness for gross volume, subtract the volume displaced by any door or window openings (opening area × thickness), then apply your contingency allowance.
▶How do I account for a door or window opening?
Enter the total area of all openings; the calculator converts that area to a volume using the wall thickness and subtracts it from the gross volume automatically.
▶Can I calculate several equal walls at once?
Yes — enter the number of equal walls and the total volume scales accordingly. Walls of different lengths or heights need to be calculated separately and added together.
▶Does this work for a tapered retaining wall?
No — this assumes uniform thickness top to bottom. A tapered (battered) wall needs the retaining wall calculator, which uses a trapezoidal cross-section instead.
▶Does this tell me what wall thickness I need?
No. Wall thickness and reinforcement are structural and local-code decisions that depend on the load and retained height — verify with approved plans or a qualified professional.
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Open calculator →Disclaimer: Concrete Wall Calculator results are estimates for general information and education only, and are not financial, tax, legal or medical advice. Verify important decisions with a qualified professional.