CalcQuarry
Construction Materials Quick Guide
CalcQuarry Construction Materials Quick Guide A compact reference for estimating gravel, paver base, concrete blocks, mortar and post hole concrete. Each section gives the standard formula, a worked example and a link to the matching free calculator on calcquarry.com. Always confirm product yields, densities and code requirements with your supplier and local building authority. Figures marked 'typical' are common rules of thumb, not guarantees.
Contents 1
Cubic yard conversions
2
Gravel: cubic yards and tons
3
Paver base depth and volume
4
Concrete blocks for a wall
5
Mortar for brick and block
6
Concrete for fence post holes
1. Cubic yard conversions Bulk materials such as gravel, soil, mulch and ready-mix concrete are sold by the cubic yard. One cubic yard is a cube 3 ft on each side. 1 cu yd = 3 ft × 3 ft × 3 ft = 27 cu ft 1 cu yd ≈ 0.7646 m³ ; 1 m³ ≈ 1.308 cu yd Cubic yards = length (ft) × width (ft) × depth (ft) ÷ 27 Depth in inches ÷ 12 = depth in feet Example: a 12 ft × 10 ft area, 4 in deep → 12 × 10 × (4 ÷ 12) = 40 cu ft → 40 ÷ 27 ≈ 1.48 cu yd. For circles use π × r² × depth; for triangles use ½ × base × height × depth. Calculator: Cubic Yard Calculator
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CalcQuarry
Construction Materials Quick Guide
2. Gravel: cubic yards and tons Find the volume as in section 1, then convert to weight if your supplier sells by the ton. Tons = cubic yards × density (tons per cu yd) Density depends on stone type, size, moisture and compaction. Many gravels fall roughly in the range of about 1.4–1.5 tons per cubic yard (typical), but ask your supplier for the figure for the exact product. Example: a 30 ft × 3 ft path, 3 in deep → 30 × 3 × 0.25 = 22.5 cu ft ÷ 27 ≈ 0.83 cu yd. At 1.4 tons/cu yd → 0.83 × 1.4 ≈ 1.17 tons. Ordering a little extra (often 5–10%) covers uneven ground and settling. Calculator: Gravel Calculator
3. Paver base depth and volume A paver installation usually has a compacted aggregate base topped with a thin bedding sand layer. Base depth depends on use and soil. Common guidance (typical) is around 4–6 in of compacted base for patios and walkways, and deeper, often 8–12 in, for driveways or poor, clay soils, plus about 1 in of bedding sand. Follow your paver manufacturer and local practice. Base volume (cu yd) = area (sq ft) × base depth (in) ÷ 12 ÷ 27 Loose aggregate compacts, so suppliers and installers often add a compaction allowance; use the factor your supplier recommends. Example: a 200 sq ft patio with 4 in base → 200 × 4 ÷ 12 = 66.7 cu ft ÷ 27 ≈ 2.47 cu yd of base. Bedding sand at 1 in → 200 ÷ 12 = 16.7 cu ft ÷ 27 ≈ 0.62 cu yd. Calculator: Paver Base Calculator
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Construction Materials Quick Guide
4. Concrete blocks for a wall Use the nominal block face, which includes one mortar joint. Blocks = (wall area − openings) ÷ face area of one block Block (nominal)
Face area
Blocks per unit area
8 × 8 × 16 in (US)
0.889 sq ft
1.125 per sq ft
450 × 225 mm (440 × 215 + 10 mm joint)
0.10125 m²
≈ 9.88 per m²
Example: wall 20 ft × 4 ft = 80 sq ft → 80 ÷ 0.889 = 90 blocks. Check by courses: 48 in ÷ 8 in = 6 courses; 240 in ÷ 16 in = 15 blocks per course; 6 × 15 = 90. Add about 5–10% for breakage and cuts → ≈ 95 blocks. Calculator: Concrete Block Calculator
5. Mortar for brick and block Wet mortar = wall volume − (units × actual unit volume) Dry materials = wet volume × 1.27 to 1.33 The dry volume factor accounts for water and sand filling voids. Split the dry volume by mix ratio: for 1:4 cement:sand, cement = 1/5 and sand = 4/5; for 1:6, cement = 1/7 and sand = 6/7. Add a waste allowance for droppings (commonly 10–25%). Example: one US modular brick is 7■ × 2¼ × 3■ in actual (62.2 cu in) and 8 × 2■ × 4 in nominal (85.3 cu in). Mortar per brick ≈ 85.3 − 62.2 = 23.1 cu in. For 500 bricks → 11,550 cu in ÷ 1,728 ≈ 6.7 cu ft wet, before waste. For bagged pre-mix, divide by the yield printed on the bag. Calculator: Mortar Calculator
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Construction Materials Quick Guide
6. Concrete for fence post holes Hole volume = π × r² × depth Square post volume = width² × depth in hole Concrete = hole volume − post volume Example: 10 in diameter hole, 24 in deep, 4×4 post (actual 3.5 × 3.5 in): Hole = 3.1416 × (0.4167 ft)² × 2 ft ≈ 1.091 cu ft. Post = (0.2917 ft)² × 2 ft ≈ 0.170 cu ft. Concrete ≈ 0.921 cu ft per hole. Bags per hole = concrete ÷ bag yield (round up) Use the yield printed on the bag. Commonly listed yields (typical) are about 0.30 cu ft for 40 lb, 0.45 cu ft for 60 lb and 0.60 cu ft for 80 lb bags. In the example: 0.921 ÷ 0.60 ≈ 1.54 → 2 × 80 lb bags per hole. Multiply by post count and add ~10% for irregular holes. Hole depth should respect your local frost line and code. Calculator: Post Hole Concrete Calculator
Quick reference Need
Formula
Cubic yards
L × W × D(ft) ÷ 27
Tons
cu yd × density
Blocks
net wall area ÷ block face
Dry mortar
wet volume × 1.27–1.33
Post concrete
πr²d − post volume
All calculators are free at calcquarry.com.
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