Calculation Methodology

BuildCost.online utilizes standard engineering geometry formulas, industry-accepted material density tables, and empirical contractor labor benchmarks to generate accurate preliminary project estimates.

1. Volume & Area Geometry

Calculators determine total surface area and volume using standard mathematical formulas:

• Rectangular Area: Length (ft) × Width (ft) = Area (sq ft)
• Cubic Volume: Length (ft) × Width (ft) × Depth (ft) = Volume (cubic feet)
• Cubic Yards Conversion: Cubic Feet ÷ 27 = Cubic Yards

2. Material Density Benchmarks

Bulk materials are converted into weight (tons) or bag counts using industry standard densities:

• Crushed Gravel: Approximately 1.4 tons per cubic yard (2,800 lbs/yd³)
• Topsoil: Approximately 1.1 to 1.3 tons per cubic yard
• Mulch: 1 cubic yard = 13.5 bags (2 cu ft bags) or 9 bags (3 cu ft bags)
• Premix Concrete: 1 cubic yard = 45 bags (80lb premix) or 60 bags (60lb premix)

3. Waste Margin & Upward Rounding

To prevent material shortages on job sites:

• A configurable waste allowance (typically 5% to 15%) is added to account for cutting loss, edge fitting, and board end trim.
• Physical purchasing units (boards, bags, posts, pavers) are rounded up to the nearest whole integer (`ceil()`).