Concrete, form area and rebar length for a poured wall.
Empty uses 10%.
Fresh concrete pushes on forms like a heavy liquid. Have forms designed for the pour height and rate. A form failure can kill. This calculator gives quantities only and does not design the wall.
Example Result
Your result will appear here
The calculated result will appear here after you press Calculate.
Enter the length, height and thickness of a poured wall, then any openings. The calculator gives the concrete to order, the area of formwork for both faces, the weight, and a simple rebar length. These are quantities only. This calculator does not design the wall.
Enter the total wall length and height.
Enter the thickness in millimetres or inches.
Add the total opening area, and the rebar spacing if you want a length.
Press Calculate for concrete, forms, weight and rebar length.
By O.E. — Partner, chairman of the board and CEO of a metal products manufacturer for 21 years; the company exports to 45 countries.
Drafted with AI assistance; calculations checked against primary sources and tested with the site's own code. About FlowUtil
Last reviewed
Net volume = (length × height − openings) × thickness
Order volume = net volume × (1 + waste)
Keep the units the same. In US work, convert thickness to feet first, so 8 in is 0.667 ft. Then divide cubic feet by 27 to get cubic yards.
Forms for wall ends and the sides of openings are extra. Order concrete in the supplier's steps, and round up. Running short mid-pour is worse than a small return. For footings or slabs on the same job, use the concrete volume calculator.
Fresh concrete pushes on forms like a heavy liquid, so the pressure at the bottom can reach the full depth of concrete:
| Wall height | Full liquid pressure |
|---|---|
| 4 ft (1.2 m) | 600 lb/ft² (29 kPa) |
| 8 ft (2.4 m) | 1,200 lb/ft² (58 kPa) |
| 10 ft (3 m) | 1,500 lb/ft² (72 kPa) |
Slow placing in warm weather can reduce it, because the lower concrete starts to stiffen. Fast pours, retarders, cold weather and self-consolidating concrete push it back toward the full figure. The formwork designer uses ACI 347 to set the pour rate.
Fresh concrete pushes on forms like a heavy liquid. Have forms designed for the pour height and rate. A form failure can kill. OSHA 29 CFR 1926.703 covers formwork on US construction sites. Other countries have their own rules.
The rebar figure counts one layer of bars each way at the spacing you enter. For the 12 × 2.4 m wall at 300 mm:
At 12 mm bar, that is about 202 kg. A wall with two layers needs twice as much. Laps, dowels into the footing, and corner bars are not included. Bar size, spacing and cover come from the design. The rebar size chart gives bar weights.
Wall thickness, reinforcement and footing are structural decisions. A basement wall holds back soil, so the same rules apply as for a retaining wall. Follow your local code or an engineer's drawings.
Costs go into the material cost calculator, and trench work is in the excavation calculator.
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