Concrete volume · Quantities for a poured wall
Concrete wall calculator
Use this concrete wall calculator to find the concrete for a poured wall. Enter its length, height and thickness, subtract the area of any doors and windows, and add an extra allowance of your own to see cubic yards, cubic metres and bags.
Concrete wall estimate
Measurement system: Imperial. Planning estimate based on the measurements shown below.
Build your estimate
Enter your measurements, then review every step.
Add up the area of every door and window cut-out: width × height for each. Leave at 0 for a solid wall.
Your choice. The 10% is only the starting entry; forms, an uneven base and spillage decide what you need.
Yields are QUIKRETE's approximate figures. Use the yield printed on your own bag for any other product.
Subtract the area of every door and window. Diagram not to scale.
Calculation and assumptions
Volume of a wall
Worked examples
A 20 ft × 8 ft wall, 8 in thick, with a door and a window (30 ft² of openings)
Concrete for the wall with 10% extra: 3.53 yd³
- Gross wall area: 20 × 8 = 160 ft²
- Net wall area: 160 − 30 openings = 130 ft²
- Volume of one wall: 130 ft² × (8 in ÷ 12) = 86.6667 ft³
- In cubic yards: 86.6667 ft³ ÷ 27 = 3.2099 yd³
- With 10% extra: 3.2099 × (1 + 0.1) = 3.5309 yd³ (2.6995 m³)
- 80 lb bags: 95.3333 ft³ ÷ 0.6 ft³ per bag = 158.89, rounded up to 159 bags
A solid 12 ft × 6 ft wall, 6 in thick, no openings
Concrete for the wall with 10% extra: 1.47 yd³
- Gross wall area: 12 × 6 = 72 ft²
- Volume of one wall: 72 ft² × (6 in ÷ 12) = 36 ft³
- In cubic yards: 36 ft³ ÷ 27 = 1.3333 yd³
- With 10% extra: 1.3333 × (1 + 0.1) = 1.4667 yd³ (1.1213 m³)
- 80 lb bags: 39.6 ft³ ÷ 0.6 ft³ per bag = 66, rounded up to 66 bags
A 6 m × 2.4 m wall, 20 cm thick, with 2 m² of openings, metric
Concrete for the wall with 10% extra: 2.73 m³
- Gross wall area: 6 × 2.4 = 14.4 m²
- Net wall area: 14.4 − 2 openings = 12.4 m²
- Volume of one wall: 12.4 m² × (20 cm ÷ 100) = 2.48 m³
- In cubic yards: 2.48 m³ ÷ 0.7646 = 3.2437 yd³
- With 10% extra: 3.2437 × (1 + 0.1) = 3.5681 yd³ (2.728 m³)
- 80 lb bags: 96.3384 ft³ ÷ 0.6 ft³ per bag = 160.56, rounded up to 161 bags
| Wall height | 6 in thick | 8 in thick | 10 in thick | 12 in thick |
|---|---|---|---|---|
| 4 ft high | 0.741 | 0.988 | 1.235 | 1.481 |
| 6 ft high | 1.111 | 1.481 | 1.852 | 2.222 |
| 8 ft high | 1.481 | 1.975 | 2.469 | 2.963 |
What the estimate assumes
- The wall is a straight, solid rectangle of one thickness. For a tapered or stepped wall, work out each part and add them, or enter the average thickness for a rough figure.
- Openings are subtracted at the wall's full thickness. Extra concrete around a frame, a lintel or a corner is not modelled.
- Reinforcement does not reduce the concrete volume here, and its quantity is not calculated.
- The wall is counted on its own. Footings, slabs and any backfill are separate quantities.
- This is a quantity estimate, not a design. It does not choose a wall thickness, height, reinforcement, drainage or mix, and it does not check a retaining wall for loads or code. Those come from your plans and a qualified professional.
All example quantities are geometry and arithmetic illustrations. Confirm measurements, product details and ordering rules with your plans and supplier.
Common questions
Concrete wall questions
How do I calculate how much concrete I need for a wall?
Multiply the wall's length by its height to get its area, then multiply by its thickness in the same unit. For feet and inches, divide the thickness in inches by 12. That gives cubic feet, which you divide by 27 for cubic yards. Subtract door and window openings from the area first, and add an allowance you choose.
Do I subtract windows and doors?
Yes. Enter the total area of all openings (width × height for each, added together) and the calculator subtracts it from the wall area before multiplying by the thickness. Extra concrete around the openings is not included, so keep your allowance in mind.
How many bags of concrete do I need for a wall?
Divide the total volume, including your extra, by the yield of the bag and round up. Choose a bag size above to see the count, using QUIKRETE's approximate yields. A wall takes far more bags than most people expect, so compare bags with ready-mix delivered by the cubic yard using your own supplier quotes.
Can I use this for a retaining wall?
It gives the concrete volume of a wall of uniform thickness, which is the quantity part of a retaining wall. It does not design one. The wall's thickness, reinforcement, drainage and footing come from your plans or an engineer, and the footing is a separate quantity.
What if the wall changes thickness?
Split it into parts that each have one thickness, calculate each, and add the volumes. For a wall that tapers steadily, the average thickness gives a reasonable estimate.
How much extra should I add?
That is your decision from the site: forms that bow, an uneven base and spillage all use concrete that the geometry does not show. The calculator starts at 10% as an example and shows the allowance separately from the net volume.
Can I enter metric dimensions?
Yes. Switch to metric to enter length and height in metres, thickness in centimetres and openings in square metres. The result is shown in cubic metres and cubic yards.
Sources
- QUIKRETE Concrete Mix No. 1101 datasheet: Read directly on October 19, 2026. States approximate yields of 0.30, 0.375, 0.45, 0.60 and 0.675 ft³ for the 40, 50, 60, 80 and 90 lb bags.
- NIST: SI Units – Length: Basis for the exact inch-to-centimetre conversion (1 in = 25.4 mm) used in the metric results.