Excavation Calculator
Calculate excavation volume, truck loads, and soil removal for foundations, trenches, and grading. Accounts for soil bulking factor.
Formula
Volume = Length × Width × Depth
Calculate bank (in-place) volume, then apply bulking factor for loose volume to determine truck loads needed.
Worked Examples
Example 1: Foundation Excavation
Problem:Dig foundation pit 30×20×4 ft. Calculate removal volume.
Solution:Bank volume: 30 × 20 × 4 = 2,400 cu ft 2,400 ÷ 27 = 88.9 cubic yards Loose volume (25% bulking): 88.9 × 1.25 = 111 loose yards Truck loads (10-yard trucks): 111 ÷ 10 = 11.1 Need 12 truckloads
Result:89 bank yards = 111 loose yards (12 trucks)
Example 2: Trench Excavation
Problem:Utility trench 100 ft long, 2 ft wide, 3 ft deep.
Solution:Bank volume: 100 × 2 × 3 = 600 cu ft 600 ÷ 27 = 22.2 cubic yards Loose (30% bulking for clay): 22.2 × 1.30 = 28.9 loose yards Trucks: 28.9 ÷ 10 = 3 loads
Result:22 bank yards = 29 loose (3 trucks)
Example 3: Pool Excavation
Problem:Pool 15×30 ft, varying depth 4-8 ft (average 6 ft).
Solution:Using average depth: 15 × 30 × 6 = 2,700 cu ft 2,700 ÷ 27 = 100 cubic yards Loose (25% bulking): 100 × 1.25 = 125 yards Trucks: 13 loads
Result:100 bank yards = 125 loose (13 trucks)
Frequently Asked Questions
What is bank volume vs loose volume?
Bank volume: soil in its natural, undisturbed state (in-ground). Loose volume: same soil after excavation (expanded by air pockets). Soil 'bulks' 20-40% when excavated. Critical for truck capacity - you need more truck space than the hole volume suggests.
How much does excavated soil weigh?
Depends on soil type and moisture. Dry soil: 70-80 lbs/cu ft. Moist soil: 90-110 lbs/cu ft. Wet soil/clay: 100-130 lbs/cu ft. A cubic yard (27 cu ft) weighs roughly 1-1.5 tons. This affects truck capacity and disposal costs.
What is the bulking factor?
Percentage soil expands when excavated. Sand: 10-15%. Loam/topsoil: 20-30%. Clay: 30-40%. Rock: 40-60%. Affects hauling - a 10-yard bank measurement becomes 12-15 yards loose. Essential for calculating truck loads needed for removal.
How do I calculate sloped excavation?
For safety, excavations need sloped sides. Slope ratios like 1:1 or 1.5:1 (horizontal:vertical). This expands top dimensions. Calculate using average width: (top width + bottom width) / 2, or use trapezoidal formulas. Slope requirements depend on soil type and depth.
What size excavator do I need?
Small mini excavator (1-2 tons): Trenches, small foundations, landscaping. Medium (5-8 tons): Residential foundations, pools. Large (15-25 tons): Commercial work, basements. Also consider reach (digging depth/radius). Rental cost increases with size.
How many dump truck loads?
Standard dump truck: 10-14 cubic yards capacity. Calculate loose volume and divide by truck capacity. Example: 50 loose yards ÷ 10 = 5 truckloads. Consider haul distance and site access for scheduling. Some areas have smaller 6-yard trucks for tight access.
Do I need permits for excavation?
Permits often required for: excavation over 4-5 feet deep, near property lines, in flood zones, or disturbing more than 1 acre. Call 811 (USA) for utility location before any digging. Violations can cause utility strikes, fines, or project shutdown.
Can I backfill with excavated soil?
Often yes, but depends on soil type and use. Good soil (not organic matter or clay) can backfill foundations after compacting. Poor soil should be replaced with select fill or crushed stone. Topsoil saved for landscaping. Excess soil may need disposal.
How deep can I excavate safely?
OSHA requires protection for excavations 5+ feet deep: sloping, benching, or shoring/trench box. Depths 4-5 feet need competent person evaluation. Never enter deep, unsupported excavation - collapses kill workers every year. Hire professional for deep excavation.
What does excavation cost?
Excavation: $50-200 per cubic yard depending on soil, access, disposal. Machine rental: $200-1,000/day based on size. Operator: $50-100/hr if not included. Disposal: $30-100/yard at landfill. Total project varies widely - get multiple quotes for significant work.
Background & Theory
Excavation removes soil for foundations, utilities, grading, and construction. Accurate volume calculation is essential for planning equipment, labor, and disposal.
Volume Formulas:
Rectangular:
Volume = Length × Width × Depth
Trapezoidal (sloped sides):
Volume = Length × ((Top Width + Bottom Width)/2) × Depth
Bulking Factor:
Loose Volume = Bank Volume × (1 + Bulking %)
Typical Bulking:
- Sand: 10-15%
- Loam: 20-30%
- Clay: 30-40%
- Rock: 40-60%
Truck Capacity:
Standard dump truck: 10-14 cubic yards
Small truck: 6-8 cubic yards
Safety Requirements:
- Call 811 before digging
- Slope walls 1:1 or support
- Never enter deep unsupported excavation