Reviewed October 2026 · Prices checked October 2026 · How we calculate

Concrete Wall Calculator: How Much Concrete for a Wall?

Enter the wall's length, height and thickness, and any openings. You get the concrete in cubic yards and bags, and whether ready-mix is cheaper.

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98bags

80 lb bags of concrete mix for a 20 × 4 ft wall

36 kg each, 7,840 lb to lift in all

98 × 80 lb bags of concrete mix$490–$784
58.67 cu ft (2.17 cu yd) with 10% extra ÷ 0.60 cu ft per bag = 97.8, rounded up.
Typical price (estimate, checked Oct 2026): $5.00–$8.00 per 80 lb bag
Your price ($ per 80 lb bag)
98 bags × $5.00–$8.00 = $490–$784Estimate

Project total (estimate where no price is entered)$490–$784

Checked Oct 2026

Bags or ready-mix? It depends on your prices: $490–$784 in bags vs $353.50–$506.75 for 2.25 cu yd of ready-mix with a short-load fee, with ready-mix usually ahead. Type your quotes below. Volume: 58.67 cu ft (2.17 cu yd).

Ready-mix, 2.25 cu yd$292.50–$393.75
Ordered in quarter yards, at least 1 yd.
Typical price (estimate, checked Oct 2026): $130.00–$175.00 per cu yd
Your price ($ per cu yd)
2.25 cu yd × $130.00–$175.00 = $292.50–$393.75Estimate
Short-load fee$61–$113
Charged by most plants on small orders.
Typical price (estimate, checked Oct 2026): $61.00–$113.00 per order
Your price ($ per order)
1 order × $61.00–$113.00 = $61–$113Estimate

Show the math

(20 × 4 ft) × 8 in ÷ 12 = 53.33 cu ft53.33 cu ft × 1.10 (10% extra) = 58.67 cu ft58.67 cu ft ÷ 0.60 cu ft per bag = 97.8 → 98 bags ($6.50 each, typical)

Your prices are saved on this device only.

How it works

The formula

volume = (length × height − openings) × thickness
bags = volume × (1 + waste) ÷ yield per bag, rounded up

Assumptions

A solid, straight wall between forms. Forms bulge a little under the weight of wet concrete; 5 to 10% extra covers that and spillage.
The footing under the wall is separate: size it with the footing calculator.
Walls that hold back soil, or are part of a house foundation, need reinforcement and an engineer or your local code. This sizes the concrete only.
Bag yields: 0.60 cu ft for 80 lb (QUIKRETE Concrete Mix). Anything past a yard or two is usually ready-mix.

Worked example

A 20 ft long, 4 ft high, 8 in thick garden wall

20 × 4 × 8/12 = 53.33 cu ft (1.98 cu yd)
With 10%: 58.7 cu ft ÷ 0.60 → 98 bags, or 2.25 cu yd of ready-mix ordered in quarter yards

Concrete by wall size

Concrete for walls, 10% extra
Wall	Cu yd	80 lb bags
10 × 3 ft, 6 in	0.61	28
20 × 4 ft, 8 in	2.17	98
30 × 4 ft, 8 in	3.26	147
40 × 8 ft, 8 in	8.69	392

Questions people ask

How much concrete for a 20 ft wall?

At 4 ft high and 8 in thick, 53.3 cu ft, or 1.98 cu yd; with 10% extra, 98 bags of 80 lb mix. At that size ready-mix is usually easier.

How thick should a concrete wall be?

Garden and landscape walls are often 6 to 8 in thick; foundation walls 8 in or more. Thickness, reinforcement and the footing for anything that holds back soil or carries a house come from your local code or an engineer.

Poured concrete or block?

Block needs no forms and goes up a course at a time; poured walls need forms but go up in one day with ready-mix. Compare the block count with the block calculator.