Block Wall Calculator — ft to blocks, mortar, cost
How to use this calculator
Enter wall length and height in feet, inches, and fractions. Select a block size, set mortar joint thickness and waste allowance. Results update instantly with block count, mortar bags, wall area, and weight.
Openings — subtract doors and windows by entering count and average size.
Grout — choose fill pattern: every course, every other, or bond beam only.
Vertical rebar — set bar size and cell spacing.
Horizontal rebar — bond beam blocks at course spacing intervals.
Cost — per block, per mortar bag, per rebar bar.
Labor — rate per ft², per block, or flat price.
Saved Calculations
| Time | Size | Blocks | Mortar | Area ft2 | Material $ | Labor | Total |
|---|
How to Calculate CMU Blocks for a Wall
This block wall calculator estimates the number of concrete masonry units (CMUs), mortar bags, grout volume, and rebar for walls of any size. Enter wall length and height in feet, inches, and fractions with 1/8" precision. Choose from four standard block sizes: 8x8x16" (most common), 8x8x8" half, 12x8x16" for wider walls, and 6x8x16" for partitions. Subtract door and window openings, and set waste allowance from 5% to 25%.
Formulas Used
Wall area (ft2) = length x height - openings. Blocks per ft2 = 1.125 for 8x16 nominal (actual 15-5/8 x 7-5/8 with 3/8" joint). Mortar: approximately 8.5 bags (80 lb) per 100 standard blocks. Grout: 0.009 ft3 per cell per course for 8" block. Rebar lap splice = 40 bar diameters per ACI 530/TMS 402.
Reinforcement per ACI 530 / TMS 402
Vertical rebar (#3 to #6) placed in grouted cells at 8" to 48" on center. Horizontal rebar (#3 to #5) in bond beam blocks at 8" to 48" course spacing. Standard 20-foot bars with 40-diameter lap splices where needed.
Export & Save
Save calculations to the built-in history table and export results as formatted text, CSV spreadsheet, A4 portrait JPG image, or a single-page PDF with diagram and data. All estimates are for planning purposes -- consult a licensed structural engineer for load-bearing applications.
