← Home & Construction Calculators
Estimate concrete volume, bags, ready-mix, two-sided formwork and approximate reinforcement length for cast-in-place walls while subtracting doors and openings.
Wall formulas
The calculator converts length, height and thickness to feet. Opening area is entered in square feet for each wall.
Worked example
A 30 ft × 8 ft wall, 8 inches thick, with 20 ft² of openings contains 146.67 ft³ before allowance. With 10% allowance, order about 5.975 yd³.
Visual guide
Use the clear concrete dimensions inside forms. Calculate pilasters, buttresses, footings and thickened sections separately.
Planning checklist
- Verify wall centerline, elevation, thickness and openings.
- Coordinate sleeves, blockouts, embeds and waterstops.
- Check bar size, spacing, laps and concrete cover.
- Engineer form ties, walers, bracing and pour rate.
- Plan placement lifts, vibration and access.
- Confirm curing and form-removal requirements.
The rebar result estimates a two-direction grid with 10% added. It does not calculate bar weight, laps by code, corners, dowels or multiple curtains.
Frequently asked questions
How are doors and windows handled?
Add their combined face area and enter it as openings per wall.
Does formwork include both wall faces?
Yes. The estimate uses twice the net face area.
Can I calculate repeated walls?
Yes. Enter one wall geometry and the number of identical walls.
Does this design reinforcement?
No. Spacing is used only for a preliminary linear-foot estimate.
Common mistakes
- Subtracting opening volume instead of face area.
- Using outside form dimensions.
- Forgetting pilasters and thickened sections.
- Ignoring a second reinforcement curtain.