A Block Wall Starts Below Grade
The block is the visible half; the footing under it is the half that decides whether the wall stays straight. The standalone Concrete Block Calculator sizes everything above grade — block, mortar, grout, and reinforcement. What it does not size is the strip footing, and that is usually the first thing you pour and the first thing you have to order. This list adds it, from the Concrete Calculator — the same math, not a lookalike.
A Worked Example: 20 ft Wall, 8 ft High
A 20-foot wall eight feet high in standard 8-inch CMU, cores grouted at 32 inches on center, joint reinforcement every other course, on a 16 × 8 in strip footing:
- 0.72 cu yd of footing concrete — about 33 × 80 lb bags
- 44 linear feet of continuous footing rebar
- 199 blocks — 15 per course across 12 courses, with 10% waste
- 16 bags of Type S/N mortar mix
- 31 bags of core-fill grout for 8 grouted cores
- 80 linear feet of vertical rebar, footing lap included
- 132 linear feet of horizontal joint reinforcement
Note that the footing concrete and the core-fill grout are almost the same volume here. People budget for one and forget the other.
Core Fill Spacing Is the Biggest Lever
Nothing else on this page moves the order as much. At 32 in o.c. the example wall has 8 grouted cores and needs about 31 bags of grout. Solid-grouting every core at 8 in takes it to 31 cores and roughly 119 bags — close to four times the grout, and a different delivery decision entirely.
That spacing is not a preference. It comes from your local code or an engineered design, and it depends on wall height, soil, and wind or seismic loading. Find the number before you price the job, because discovering it after you have ordered is an expensive correction.
Two Kinds of Rebar, Both Needed
Footing bars run horizontally and continuously along the footing — two continuous bars is the usual residential detail, and that is what this list quotes. Vertical bars stand up through the grouted cores and lap down into the footing to tie the wall to it.
The vertical figure here already carries its own footing lap allowance, so the two lines are added, not overlapped. Do not subtract one from the other thinking you have double-counted — they are different steel doing different jobs, and a wall short of either one is not the wall the design assumed.
What Sets the Footing Size
Twice the block width, and at least as deep as the block is wide, is a common residential starting point — 16 × 8 inches under standard 8-inch CMU. Three things override it: frost depth, since the footing must bear below the frost line or it will heave; soil bearing capacity, since weak soil needs a wider footing to spread the same load; and the load above, since a foundation wall carrying a house is a different problem from a freestanding garden wall.
The size selector here offers planning defaults, not code minimums. Your building department has the real numbers, and the footing is the one line on this list you cannot retrofit.
Permits and Engineering
Whether you need a permit depends on what the wall does. A foundation wall is structural by definition. A freestanding wall becomes a permit and engineering question as height and wind exposure increase. Any wall retaining soil is an engineered problem regardless of material — if that is what you are building, use the retaining wall materials list instead, since a retaining wall needs drainage this list does not include.
Rebar spacing, footing dimensions, and the grout schedule all come out of that design. This calculator gives you defaults to plan and budget against; it does not replace the design.
What This List Does Not Include
Sand and cement if you are mixing mortar from scratch rather than buying pre-blended bags, anchor bolts or straps at the top of the wall, bond beam block and its steel where the design calls for one, waterproofing or damp-proofing on below-grade faces, and drainage of any kind. Bulk block is delivered by the pallet with a freight charge, so price delivery alongside the material.
The grout and rebar figures assume a standard two-core 8-inch block. Deeper block holds more grout per core, so treat those two lines as planning estimates if you are building in 10 or 12-inch units.
Export Your List
Use the buttons above the article to copy the list, download a PDF, or email it to yourself. When supplier links are configured, the “Send this list to Home Depot” section opens a live, in-stock search for every line item — one click per material.
Related
- Concrete Block Calculator — the wall on its own
- Concrete Calculator — footings and slabs
- Brick & Block Wall Installation — laying technique
- Retaining Wall Materials List — if the wall holds back soil
- All project materials lists
Written by Daniel McCarney — AceCalc