Concrete Wall Calculator
Find out exactly how much concrete you need for a wall — cubic yards, bags, water, weight and cost, with openings deducted automatically.
Your wall
Use this if you’re pouring several matching sections.
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Per-wall breakdown
50 × 80 lb bags per wall
Mixing time
5 h
One person, 50 bags
Bagged vs ready-mix
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The short answer
Multiply the wall’s length by its height by its thickness (all in feet) to get cubic feet, subtract any door or window openings, then add 5–10% waste. Divide by 27 for cubic yards, or by a bag’s yield (0.60 cu ft for an 80 lb bag) for a bag count. A typical 10 ft × 6 ft wall at 8 inches thick needs roughly 1.5 cubic yards, or about 67 × 80 lb bags.
Concrete needed by wall thickness
Figures below are for a 10 ft long, 6 ft high wall section with no openings deducted and no waste added.
| Thickness | Concrete | Cubic yards | 80 lb bags | 60 lb bags | 40 lb bags |
|---|---|---|---|---|---|
| 4 in | 20.0 cu ft | 0.74 | 34 | 45 | 67 |
| 6 in | 30.0 cu ft | 1.11 | 50 | 67 | 100 |
| 8 in | 40.0 cu ft | 1.48 | 67 | 89 | 134 |
| 10 in | 50.0 cu ft | 1.85 | 84 | 112 | 167 |
| 12 in | 60.0 cu ft | 2.22 | 100 | 134 | 200 |
Once a single wall section clears about 1 cubic yard, ready-mix delivery is usually worth pricing against bags — the calculator above flags this for your exact numbers.
How to calculate concrete for a wall
A wall’s volume is simply its face area times its thickness, with any openings subtracted.
- Find the gross volume. Length × height × thickness, all converted to feet.
- Subtract openings. For each door or window, multiply its width × height × wall thickness, then subtract.
- Multiply by the number of wall sections. This gives the total concrete needed.
- Add waste. 5–10% covers form leakage, spillage and slightly over-poured sections.
- Convert to your order unit. Divide by 27 for cubic yards, or by a bag’s yield and round up per wall for bagged concrete.
Worked example
A 10 ft long, 6 ft high wall, 8 inches thick, with one 3 ft × 6.7 ft door opening, using 80 lb bags:
- Gross volume10 × 6 × 0.667 = 40.0 cu ft
- Door opening volume3 × 6.7 × 0.667 = 13.4 cu ft
- Net volume40.0 − 13.4 = 26.6 cu ft
- Plus 10% waste29.3 cu ft
- Divide by bag yield29.3 ÷ 0.60 = 48.8
- Round up49 × 80 lb bags
That’s about 1.1 cubic yards — close enough to a ready-mix minimum that it’s worth getting a delivery quote before committing to bags.
Bagged concrete vs ready-mix truck
| Bagged concrete | Ready-mix truck | |
|---|---|---|
| Best for | Small walls, under ~1 cu yd | Larger walls, 1 cu yd and up |
| Labor | Mixed by hand or mixer, one bag at a time | Delivered ready to pour |
| Consistency | Varies batch to batch | Consistent, engineered mix |
| Minimum order | None — buy what you need | Often 1 cu yd, short-load fees below ~3–4 yd |
| Typical cost per yard | Usually higher per yard | Usually lower per yard at volume |
For a single small garden wall, bags are simpler and there’s no minimum order. For anything approaching or exceeding a cubic yard, get a ready-mix quote — pouring an entire wall from one truck is faster and more consistent than mixing dozens of bags by hand.
Pouring a wall: a quick checklist
- Build the formsBoth faces of the wall need rigid formwork, braced so it won’t bulge under the weight of wet concrete.
- Place reinforcementVertical and horizontal rebar per your local code, supported so it stays centered in the pour, not resting on the base.
- Pour in liftsFill in stages rather than all at once, consolidating with a vibrator or rod to remove air pockets between lifts.
- Screed and finish the topLevel the top of the wall and finish it before the surface starts to set.
- Cure before stripping formsLeave forms in place at least 24–48 hours, longer in cold weather.
- Protect while curingKeep the surface damp or covered for several days to reach full strength around 28 days.
Common mistakes
- Forgetting to subtract openingsDoors and windows displace real volume. Skip this and every wall section is over-ordered.
- Rounding the total instead of per wallRound bags up per individual wall section, then add them — rounding only the grand total can leave one section short.
- Underestimating form pressureWet concrete is heavy. Undersized bracing lets forms bulge or blow out mid-pour.
- Skipping rebarUnreinforced walls crack more readily and may not meet local code for load-bearing or retaining use.
- Pouring the whole wall in one liftLarge uninterrupted pours trap air and can cause honeycombing; placing in lifts with consolidation gives a denser wall.
- Stripping forms too earlyRemoving forms before the concrete has enough strength risks bulging, cracking, or a damaged face finish.
What this calculator assumes
Adjust your result if your project differs from these.
- Bag yields of 0.60, 0.45, 0.375 and 0.30 cu ft for 80, 60, 50 and 40 lb bags
- Wall treated as a flat rectangular volume (length × height × thickness)
- Openings treated as simple rectangles subtracted at the same thickness as the wall
- Standard concrete mix, not fast-setting or high-strength products
- Water of roughly 3 quarts per 80 lb bag
- Mixing at about 6 minutes per 80 lb bag, per person
- Ready-mix vs bagged guidance uses a 1 cubic yard rule of thumb, not a supplier quote
- Prices are whatever you enter; they are not live market rates
Common questions
How much concrete do I need for a wall?
Multiply the wall’s length by its height by its thickness (in feet) to get cubic feet, subtract any door or window openings, then add 5 to 10 percent waste. Divide by 27 for cubic yards, or by a bag’s yield for bag count.
How thick should a concrete wall be?
Garden or landscaping walls are often 4 to 6 inches thick. Load-bearing foundation and retaining walls are typically 8 to 12 inches, depending on height and local code.
Can I use bagged concrete for a wall, or do I need ready-mix?
Bagged concrete works for small walls, generally under about 1 cubic yard. Beyond that, a ready-mix truck is usually faster, more consistent and often cheaper per yard.
How much does a cubic yard of concrete cost?
Ready-mix pricing varies by region and supplier, commonly in the range of 130 to 180 dollars per cubic yard, plus any delivery or short-load fees.
Do I need rebar in a concrete wall?
Most load-bearing or retaining walls need vertical and horizontal reinforcement per local code. Low garden walls under about 2 feet are sometimes poured unreinforced, but checking local code is recommended.
How long does a concrete wall take to cure?
Forms can often come off after 24 to 48 hours. The wall reaches most of its working strength by about 7 days and full strength at roughly 28 days.
Can I pour a concrete wall without forms?
No. Poured concrete walls need formwork on both faces to hold the shape while the concrete is fluid; only fully dry-stacked block systems avoid forms.
How many 80 lb bags make a cubic yard?
About 45 bags of 80 lb concrete mix make one cubic yard, since each bag yields roughly 0.60 cubic feet and a cubic yard is 27 cubic feet.
What’s the minimum order for ready-mix concrete?
Many suppliers set a one cubic yard minimum, and often charge a short-load fee below around 3 to 4 cubic yards. Check with your local supplier.
How much water does a bag of concrete need?
About 3 quarts (2.8 L) per 80 lb bag, 2.25 quarts for a 60 lb bag, and 1.5 quarts for a 40 lb bag. Add gradually to a firm, workable consistency.
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Concrete Wall Estimate
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materialcalculate.com/concrete-wall-calculator/
Project
| Wall dimensions | — |
| Thickness | — |
| Openings deducted | — |
| Number of wall sections | — |
| Waste allowance | — |
Per wall
| Concrete per wall | — |
| 80 lb bags per wall | — |
Total shopping list
| Total cubic yards | — |
| 80 lb bags | — |
| 60 lb bags | — |
| 40 lb bags | — |
| Water needed | — |
| Dry weight to move | — |
| Estimated cost | — |
Notes
Estimate generated by materialcalculate.com. Assumes rectangular wall volume with standard concrete mix and yields of 0.60, 0.45, 0.375 and 0.30 cu ft for 80, 60, 50 and 40 lb bags. Confirm quantities with your supplier before buying.