About

Concrete walls are fundamental to construction, serving as basement foundations, retaining walls for landscaping, or structural barriers. Unlike simple slabs, wall calculations often require a two-part approach: the vertical wall itself and the horizontal footing (or footer) that distributes the load to the soil. These two components are frequently poured at different times, sometimes requiring different concrete mixes.

This calculator separates these volumes to assist in precise ordering. It allows for the input of wall dimensions and optional footer dimensions, summing them for a total project requirement. It is an essential tool for avoiding the common error of neglecting the footing volume in initial estimates.

Formulas

The volume is calculated geometrically for both the wall and the footing. The calculator treats them as rectangular prisms.

V_wall = L × W_wall × H_wall

V_footing = L × W_foot × H_foot

Reference Data

Wall Type	Typical Thickness	Rebar Config	Concrete Strength
Basement Foundation	8 - 10 inches	#4 Grid @ 12" OC	3000 - 4000 psi
Retaining Wall (Low)	8 inches	#4 Vert @ 16" OC	3000 psi
Retaining Wall (High)	10 - 12 inches	#5 Vert @ 12" OC	4000 psi
Garden Wall	6 inches	#3 Grid @ 18" OC	2500 psi
Stem Wall	6 - 8 inches	#4 Horiz (2 bars)	3000 psi
Blast/Safe Room	12+ inches	Double Grid #5	5000+ psi

Frequently Asked Questions

No. In this calculator, the Wall Height is the vertical measurement of the wall starting *from the top of the footer*. If your plan specifies a total height from the bottom of the footing, subtract the footing height to get the correct Wall Height input.

A general rule of thumb for residential foundations is that the footing width should be twice the width of the wall it supports (e.g., an 8-inch wall gets a 16-inch footer). Always check local building codes.

Rebar takes up volume, but it is negligible in the context of concrete ordering (less than 1%). Do not subtract volume for rebar. In fact, standard practice is to ignore the rebar volume to ensure you have enough concrete to fully encapsulate it.

Footers are often poured first and allowed to cure (harden) before forms are built for the walls. This creates a 'cold joint'. You might order the concrete for the footer on Tuesday and the wall concrete on Friday, so knowing the separate volumes is crucial.

OC stands for 'On Center'. It means the measurement is taken from the center of one rebar to the center of the next, rather than the gap between them.