Concrete Block Calculator. Concrete block calculations require wall dimensions. Formula: Blocks equals Wall Area divided by Block Face Area. Standard block 8×8×16 inches covers 128 sq inches or 0.89 sq ft. Example 8 ft high by 20 ft long wall: 160 sq ft divided by 0.89 equals 180 blocks. Add 5-10 percent waste equals 189 blocks, order 190. Block types and sizes: Standard hollow 8×8×16 most common, lightweight. Half block 8×8×8 for ends. Solid block heavy, foundations. Corner block L-shape. Bond beam blocks with cutout for rebar. Pilaster blocks thicker for columns. Caps solid flat for wall tops. Prices: Standard block 1.50-3.00 each. Solid blocks 3-5 each. Specialty blocks 4-8 each. Mortar calculation: Bags equals Blocks divided by 8. Example 180 blocks: 180 divided by 8 equals 22.5, order 23 bags of type N or S mortar. One 80-pound bag lays approximately 8 standard blocks with 3/8 inch joints. Reinforcement critical: Vertical rebar every 4 feet, plus each corner and opening. Horizontal rebar every 4 courses (32 inches). Grout-filled cells provide reinforcement. Building codes specify requirements based on height and seismic zone. Footing for block walls: Foundation 12 inches wide minimum, twice wall thickness. Depth below frost line 36-48 inches depending on region. Rebar in footing ties to vertical wall rebar. Compacted gravel base 4-6 inches. Level footing critical for plumb wall. Costs: Block materials 8-15 per sq ft. Mortar and grout 2-4 per sq ft. Rebar and reinforcement 1-2 per sq ft. Labor 10-25 per sq ft. Total 20-45 per sq ft installed depending on height and reinforcement. Example basement foundation: 8 ft high, 120 ft perimeter. Area: 960 sq ft. Blocks: 1,079 at 2 equals 2,158. Mortar: 135 bags at 10 equals 1,350. Rebar and grout: 1,500. Labor: 15,000. Total: 20,000 or 21 per sq ft. Laying blocks: First course mortared to footing, level critical. Stack subsequent courses in running bond offset 8 inches. Apply mortar to block ends and bed. Tool joints concave for weather seal. Check plumb and level constantly. Fill cores with grout around rebar. Cap top course protects from water. Common mistakes: Calculating only wall face not accounting for openings for windows and doors, subtract these accurately. Wrong block size, nominal 8 inch is actually 7-5/8 inches, affects calculations. Not planning for half blocks at ends, order extras. Forgetting reinforcement doubles back for materials. First course not level compounds errors upward. Joints too thin or too thick, 3/8 inch mortar joint standard. Pro tips: Snap chalk lines on footing marks first course placement. Use line string between corner blocks keeps courses straight. Fill vertical joints completely prevents water infiltration and strengthens wall. Tool all joints while mortar still workable. Clean block faces with dry brush removes mortar smears easier than after hardening. Check every block with level before setting next, corrections difficult later. Block vs poured concrete: Block walls faster to build, modular, easier for openings. Poured concrete stronger, monolithic, better for high walls. Block economical for most foundation and retaining walls. Poured better where high strength needed. Both require skilled labor and formwork or masonry expertise. Insulating blocks: Insulated concrete forms (ICF) hollow blocks filled with concrete, foam insulation built in. Superior energy efficiency. Cost 25-35 per sq ft installed more than standard block. Popular for energy-efficient homes. Standard block walls often furred out and insulated interior. Surface finishes: Exposed block can be painted or stuccoed. Parging (coating with mortar) smooth finish. Stucco traditional cement plaster. Paint block filler seals porous surface first then paint. Interior often drywalled over furring strips. Each finish adds cost. Retaining walls: Design critical, soil pressure requires engineering over 4 feet high. Footing steps down slope. Backfill with gravel for drainage. Weep holes at base every 6-8 feet prevents water buildup. Geogrid reinforcement for tall walls. Cap blocks prevent water entry. Permit required most areas over 4 feet. FAQ: How many blocks for wall? Measure length times height in feet, multiply by 1.125 equals number of standard 8×8×16 blocks. 100 sq ft needs 113 blocks. How much mortar? One 80-pound bag lays 8 blocks, divide block count by 8 for bags needed. Can I build block wall DIY? Possible for small non-structural walls under 4 feet. Foundations and tall walls hire professional mason. What reinforcement needed? Depends on wall height and use, typically vertical rebar every 4 feet minimum, horizontal every 4 courses. Check local building codes. Block or poured concrete? Block faster and easier for moderate height. Poured concrete stronger for tall basement walls and heavy loads.