Concrete Wall Calculator

1. Enter the wall length and height in feet and the thickness in inches.
2. Enter the total openings area in square feet to subtract doors and windows, if any.
3. Set the number of walls for identical walls, and a 5 to 10 percent waste allowance.
4. Pick a bag size for a bag count, then read the cubic yards to order.

Here is what each result line means:

A concrete wall calculator turns the length, height and thickness of a poured wall into the amount of concrete to order. It is for cast-in-place walls: foundation walls, basement walls, stem walls and retaining-wall stems formed and poured on site.

A wall is a thin, tall slab stood on edge, so the volume is its face area times its thickness, less any openings. The tool converts feet and inches to cubic yards and bags and adds a waste allowance for form deflection and footing over-pour. To get the mix right use the concrete mix calculator, and size the mix water with the water cement ratio calculator.

A wall is a rectangular panel, so its volume is length times height times thickness. Openings such as doors and windows are hollow, so their face area is subtracted before multiplying by the thickness.

1. Multiply length by height for the gross face area, then subtract the openings area.
2. Convert the thickness from inches to feet by dividing by 12, and multiply by the net area for cubic feet.
3. Multiply by the number of walls, then add the waste allowance.
4. Divide by 27 for cubic yards, multiply by 0.0283168 for cubic meters, and divide cubic feet by the bag yield for a bag count.

For the footing the wall bears on, size it with the cement calculator for the binder in the mix.

Suppose you are pouring a foundation wall 20 feet long and 8 feet tall at 8 inches thick, with no openings and 10 percent waste.

Calculation: the face area is 20 x 8 = 160 sq ft and the thickness is 8 / 12 = 0.667 ft. Volume = 160 x 0.667 = 106.7 cu ft, or 106.7 / 27 = 3.95 cu yd. Adding 10 percent waste gives 117.3 cu ft, about 4.35 cu yd and roughly 196 eighty-pound bags.

The lesson: at well over four cubic yards and nearly 200 bags, a wall this size is a clear ready-mix order, not a bag job.

Foundation and Basement Walls

Residential poured foundation walls are commonly 8 to 10 inches thick, and the thickness rises with the height retained and the loads. The required figure comes from your plans or code.

Stem Walls

A short stem wall between the footing and the frame is often 8 inches, tuned to the load path.

Retaining Walls

Retaining-wall stems are designed for the soil they hold back and are usually thicker at the base, often with a tapered or stepped section that you work out in parts.

These are common figures, not a specification. Thickness, reinforcement and the design of a retaining or load-bearing wall come from an engineer or your local code.

Thickness

Thickness multiplies the whole face, so it moves the volume more than any other input. Confirm it before ordering, because an extra inch over a large wall is a lot of concrete.

Openings

Doors and windows remove concrete. On a wall with many openings, subtracting them avoids over-ordering, though small openings are sometimes ignored for a margin.

Footing Over-pour

Concrete slumps into an uneven footing joint and the base of the forms, so real walls use a little more than the face geometry. A waste allowance covers it.

Number of Walls

Repeating identical walls multiplies any per-wall error, so confirm one wall first, then set the count.

A poured concrete wall and a concrete block wall are sized differently, and this tool covers the poured case.

For a block wall, count the units and mortar instead; for the delivered price of a poured wall, the concrete cost calculator in the related tools prices it by the yard.

Ordering Concrete for a Wall Pour

Size the wall in cubic yards and add waste before you call the supplier, so you can pour the whole wall in one continuous lift.

Deducting Openings

For a wall with doors or windows, subtract their area so you do not pay for concrete that never gets placed.

Planning the Pour and Access

The weight and net area help you plan the forms, the lift height and how much bracing and labour the pour needs.

1. Mixing Up Thickness Units

Enter length and height in feet and thickness in inches, as the fields are labelled. Entering thickness in feet shrinks the result twelvefold.

2. Forgetting to Subtract Large Openings

A garage door or picture window is a big share of a wall. Leaving it in over-orders; subtract its area.

3. Over-subtracting Small Openings

Deducting every small penetration can leave you short, since the forms still hold some concrete there. Keep a waste margin.

4. Ignoring Footing Over-pour

Concrete settles into the footing joint and form base. A waste allowance covers the extra; skipping it risks running short at the top.

5. Treating the Estimate as a Design

Volume is not strength. Thickness, reinforcement and the design of a retaining or load-bearing wall come from an engineer or code, not from this tool.

The arithmetic is exact; the usefulness depends on the dimensions, thickness, openings and waste you enter.

Multiply the length by the height for the face area, subtract any openings, then multiply by the thickness in feet and divide by 27 for cubic yards. A 20 by 8 foot wall 8 inches thick is 160 x 0.667 = 106.7 cubic feet, about 3.95 cubic yards before waste.

It depends on the size and thickness. A 20 by 8 foot wall at 8 inches is about 3.95 cubic yards, or 4.35 with a 10 percent allowance, roughly 196 eighty-pound bags. Enter your own length, height and thickness above for the exact figure.

Residential poured foundation walls are commonly 8 to 10 inches, rising with height and load, but the required thickness comes from your plans, code or engineer. This tool turns whatever thickness you enter into concrete volume.

Add up the face area of the openings in square feet and enter the total. The tool subtracts it from the wall face before working out the volume, so you do not order concrete for space that stays hollow.

A 20 by 8 foot wall at 8 inches is roughly 196 eighty-pound bags with waste, which is far too many to mix by hand, so a wall this size is a ready-mix order. The tool gives the bag count for your wall and bag size, rounded up.

Yes, 5 to 10 percent. Formed walls lose concrete to form deflection, the footing joint and spillage, and a cold joint partway up a wall is a weak point, so a margin keeps the pour continuous.

No. It sizes a solid poured wall. A block wall is estimated by counting concrete masonry units and mortar, not by volume, so use a block count for that case.

For a straight stem of constant thickness, yes. A tapered, stepped or battered retaining wall varies in section, so break it into parts and add them, and have the design confirmed by an engineer.

No. The calculation runs entirely in your browser and nothing you enter is stored or sent anywhere.

• QUIKRETE Concrete Mix 1101 data sheet (QUIKRETE; bag yields 0.60, 0.45 and 0.30 cu ft).
• National Ready Mixed Concrete Association (NRMCA; ready-mixed concrete and ordering).
• American Cement Association (American Cement Association; concrete and foundation walls).