How it works
The calculator finds the wall area, multiplies it by the grout rate for your block width and grout spacing, and divides by the yield of one bag.
Wall area = Length × Height − Σ (Width × Height × Count of openings), or Blocks × 8/9 sq ft
Grout = Wall area × Rate ÷ 100 × (1 + Extra ÷ 100)
Bags = ⌈ Grout ÷ Yield per bag ⌉
The rate is the volume of grout in cubic feet per 100 sq ft of wall from CMHA TEK 4-2A Table 3 – for example 36.1 for an 8 in wall with every cell grouted, or 6.1 with a grouted cell every 48 in. ⌈ ⌉ means rounding up to the next whole bag.
Units are converted internally, so you can enter the wall in feet or meters. This tool estimates material quantity only; which cells are grouted and reinforced comes from your plans, local code or a qualified professional.
Worked example
Inputs
- Measure by
- Known wall area
- Wall area
- 100 sq ft
- Block (wall) width
- 8 in (203 mm)
- Grouted cells
- Every cell (solid grouted)
- Yield per bag
- 0.68 cu ft
- Extra allowance
- 0 %
Result
- Grout volume
- 36.1 cu ft (1.34 cu yd)
- Bags of grout
- 54
- Wall area
- 100 sq ft
Common mistakes
- Counting every core when only reinforced cells are grouted. A wall grouted every 48 in uses about a sixth of the grout of a solid-grouted wall.
- Forgetting bond beams and lintels. Horizontal courses filled with grout are extra; TEK 4-2A gives separate figures for them.
- Using mortar instead of grout. Grout is a fluid mix made to flow into the cores around the steel; check the bag says it meets ASTM C476.
- Deciding which cells to grout from a calculator. Reinforcement and grouting are part of the wall design from your plans, local code or a qualified professional.
Assumptions and limits
- Grout per wall area is taken from CMHA TEK 4-2A Table 3 (cu ft per 100 sq ft by wall width and grout spacing), which assumes two-core hollow units and includes 3 % waste.
- A block count is turned into wall area at 8/9 sq ft per standard 8 × 16 in face (TEK 4-2A).
- The table is for US nominal block widths; metric blocks of a similar width are approximated by the nearest size.
- Bags are rounded up after any extra allowance. This is a material quantity only, not a structural design.
Frequently asked questions
How much grout does it take to fill an 8 inch block wall?
TEK 4-2A gives 36.1 cu ft per 100 sq ft of 8 in wall with every cell grouted, including 3 % waste. That is about 0.32 cu ft per standard block (36.1 ÷ 112.5).
How many blocks does one bag of grout fill?
QUIKRETE says an 80 lb bag of Core-Fill Grout fills the cores of about 3 standard 8 × 8 × 16 in blocks. With the TEK 4-2A rate and a 0.68 cu ft bag, 100 sq ft of solid-grouted 8 in wall takes 54 bags.
What if only some cells are grouted?
Choose the spacing of the grouted cells. At 48 in on an 8 in wall, TEK 4-2A gives 6.1 cu ft per 100 sq ft instead of 36.1.
Should I order bagged grout or ready-mix?
For a large or solid-grouted wall, the bag count can get high; compare it with a ready-mix or pumped grout quote for the cubic yards shown here.
Sources
- TEK 04-02A – Cost Estimating Guide for Concrete Masonry, Table 3 (PDF) — Concrete Masonry & Hardscapes Association (formerly NCMA). Table 3 "Grout Volume Estimation for Hollow Single Wythe Concrete Masonry Walls", cu ft per 100 sq ft for 6–14 in walls at grout spacing 8–120 in (8 in, every cell: 25.6 / 36.1 / 47.0 / 58.9 / 74.5); "Assumes two-core hollow concrete masonry units and 3% waste"; preblended grout 80 lb bag ≈ 0.66 cu ft.
- TEK 04-02A – Cost Estimating Guide for Concrete Masonry — Concrete Masonry & Hardscapes Association (formerly NCMA). Nominal 8 × 16 in face = 8/9 sq ft per unit; 112.5 units per 100 sq ft before waste, 119 with a 5 % allowance.
- QUIKRETE Core-Fill Grout – Fine (No. 1585-08) Product Data Sheet — The QUIKRETE Companies. "Each 80 lb (36.2 kg) bag … will yield approximately 0.68 ft3 (19 L)" and fills "approximately 3 standard 8 in x 8 in x 16 in" block cores (default 0.68 cu ft).
- QUIKRETE Core-Fill Grout – Coarse (No. 1585-07) Product Data Sheet — The QUIKRETE Companies. "Each 80 lb (36.2 kg) bag … will yield approximately 0.65 ft3 (18.4 L)".
- NIST Handbook 44, Appendix C – General Tables of Units of Measurement — National Institute of Standards and Technology. Exact unit definitions: 1 in = 2.54 cm, 1 yd³ = 27 ft³, 1 US gal = 231 in³, 1 lb = 0.45359237 kg.
Method reviewed November 6, 2026