Core Fill Grout Calculator
Calculate cubic yards of core fill grout needed to fill all cells of a CMU block wall based on its area, plus total cost.
How this calculator works
Fully grouting every cell of a standard 8-inch CMU wall consumes roughly 1 cubic yard of grout per 107 sq ft of wall face. This calculator divides your wall’s area by that coverage rate to get the cubic yards to order.
Formula: Cubic yards = Wall area (sq ft) ÷ 107 sq ft per yd³.
Worked example
A wall 20 ft long x 8 ft high (160 sq ft), fully grouted:
- Area: 20 × 8 = 160 sq ft
- Cubic yards: 160 ÷ 107 ≈ 1.4953 → 1.50 yd³
- At $160/yd³, that’s $239.25.
Coverage reference
| Wall area | Cubic yards (full-cell, ~107 sq ft/yd³) |
|---|---|
| 10 x 4 ft | 0.37 yd³ |
| 20 x 8 ft | 1.50 yd³ |
| 40 x 16 ft | 5.98 yd³ |
How to measure your wall for grouting
Measure the wall’s total length and height in feet to get the face area, the same measurement you’d use for a block count. This calculator assumes full-cell grouting — if your engineering spec calls for partial grouting (rebar cells only, at a set spacing), scale the result down by the ratio of grouted cells to total cells rather than using the full-area figure directly.
Frequently asked questions
How much grout do I need to fill all the cells of a block wall?
Fully grouting every cell of a standard 8 in CMU wall takes roughly 1 cubic yard of grout per 107 sq ft of wall face. Enter your wall's area in square feet and this calculator converts it to the cubic yards you need to order.
Do I need to grout every cell, or just some?
It depends on your engineering spec — many reinforced walls only need grout in cells containing vertical rebar (partial grouting), often every 24, 32, or 48 inches on center, rather than every cell. This calculator assumes full-cell grouting; for partial grouting, scale down proportionally based on your actual grouted cell spacing versus the full 8-inch cell spacing.
Why is core fill grout priced and measured differently from mortar?
Mortar sets the block courses and fills the thin joints between units, sold by the 80-lb bag. Core fill grout is a more flowable mix pumped or poured into the hollow cores of already-laid block to add structural strength and encase rebar, typically ordered by the cubic yard from a ready-mix supplier or grout pump service rather than bagged.
Does core fill grout need vibration or consolidation like poured concrete?
Yes, for tall pours — grout poured in lifts taller than about 4-5 feet needs to be consolidated (rodded or vibrated) to eliminate air pockets and voids around rebar, similar to concrete. Very tall walls are often grouted in multiple lower lifts rather than one continuous pour to keep grout pressure from blowing out the block face.
Is this the same material as the core fill for a concrete block foundation wall?
Conceptually yes — core fill grout works the same way whether it's a foundation wall, retaining wall, or structural block wall above grade, encasing vertical rebar inside the block cells. Foundation and retaining walls are more likely to require full-cell grouting throughout, given their higher structural and lateral-load demands.
Estimates only. Verify quantities with your supplier before purchasing.