Concrete Wall Calculator
Walls are tall, thin volumes with holes in them. Enter the run, the height and the thickness — this concrete wall calculator deducts the openings and answers in yards, bags and cost.
Concrete needed
4.00 yd³
108.0 ft³
Estimated cost
$660
at $165 per yd³
Approx. weight
14,364 lb
≈ 7.2 tons
Bagged mix
180
80-lb bags
240
60-lb bags
360
40-lb bags
Before you order: add about 10% for uneven subgrade and spillage — that's 4.40 yd³ or 199 × 80-lb bags.
Formula
Gross volume minus openings, both scaled by the wall thickness:
volume (ft³) = [length × height − openings (ft²)] × [thickness (in) ÷ 12] cubic yards = volume (ft³) ÷ 27
Why openings scale by thickness: a door doesn't run the full wall depth for free — the form stops there, so every square foot of opening removes one thickness-foot of concrete.
Example
- Wall 30 ft × 8 ft, 6 in. thick, with 24 ft² of door and window openings.
- Gross: 30 × 8 × 0.5 = 120 ft³; openings: 24 × 0.5 = 12 ft³.
- Net: 108 ft³ = 4.00 yd³ — order about 4.5 yd³ with the 10% allowance.
- Bags: 108 ÷ 0.60 = 180 × 80-lb — this pour wants a truck.
Frequently Asked Questions
How much concrete does a wall take?
Multiply length × height × thickness, then subtract the openings. A 30 ft wall, 8 ft tall, 6 inches thick with 24 ft² of openings nets 108 ft³ — exactly 4 cubic yards, or 180 of the 80-lb bags.
How thick should a poured concrete wall be?
Garden and retaining walls commonly pour 6–8 inches; structural basement walls 8–10 inches with reinforcement per an engineer's spec. Thickness is where the volume lives — doubling it doubles the order.
Do I subtract door and window openings?
Yes. Every opening is formed solid-to-void, and its volume is real concrete you don't need: a 3 × 7 ft door in a 6-inch wall is 10.5 ft³ — a third of a yard. Enter total opening area above and the calculator deducts it.
Is pouring a wall a DIY job?
Small landscape walls (under about 2 yards) are within reach with bagged mix and careful formwork. Tall or structural walls need engineered forms that resist enormous liquid pressure — usually hired out, with this estimate used to sanity-check the quote.