Decorative & Hardscape · Contractor Estimation Tool

Lava Rock Landscaping Calculator

Calculate lightweight red or black volcanic scoria lava rock in cubic yards, pounds, tons, and 0.5 cu ft bags.

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How the Lava Rock Landscaping Calculator Works

Ultra-lightweight porous volcanic stone in red or black hues. Weighs roughly half as much as standard gravel per cubic yard. Our Lava Rock Landscaping Calculator computes exact geometric volume in cubic feet and cubic yards, then converts volume into US short tons (2,000 lbs) using the typical bulk density of Volcanic Lava Rock (3/4" – 1-1/2" Scoria) (1,350 lb/yd³ or 0.68 tons/yd³).

Mathematical Formula for Lava Rock:
1. Area (sq ft) = Length (ft) × Width (ft)
2. Volume (cu ft) = Area (sq ft) × [Depth (inches) ÷ 12]
3. Volume (cu yd) = Volume (cu ft) ÷ 27
4. Recommended Volume = Base Volume × (1 + 10% Ordering Adjustment)
5. Estimated Tons = Recommended Cubic Yards × 0.68 tons/yd³

Step-by-Step Worked Example

Example Project: 25 ft × 6 ft Area at 3 Inches Depth (+10% Adjustment)

Surface Area: 25 ft × 6 ft = 150 sq ft.
Base Volume: 150 sq ft × (3 ÷ 12) = 37.5 cu ft (1.39 cubic yards).
With +10% Ordering Adjustment: 1.39 yd³ × 1.10 = 1.53 cubic yards.
Weight in US Short Tons: 1.53 yd³ × 0.68 tons/yd³ = 1.03 tons (2,063 lbs).

Primary Applications & Contractor Best Practices

Low-maintenance xeriscape planter beds: Engineered for reliable coverage, drainage stability, and long-term performance.
Gas fire pit burner media and surrounds: Engineered for reliable coverage, drainage stability, and long-term performance.
Lightweight rooftop and raised planters: Engineered for reliable coverage, drainage stability, and long-term performance.
Moisture-retaining shrub borders: Engineered for reliable coverage, drainage stability, and long-term performance.

Coverage & Tonnage Quick Reference Table (Volcanic Lava Rock (3/4" – 1-1/2" Scoria))

Estimated cubic yards and US short tons (including +10% ordering adjustment) across common project square footages:

Project Area	2" Depth	3" Depth	4" Depth	6" Depth
100 sq ft	0.46 t (0.68 yd³)	0.69 t (1.02 yd³)	0.92 t (1.36 yd³)	1.38 t (2.04 yd³)
250 sq ft	1.15 t (1.70 yd³)	1.72 t (2.55 yd³)	2.29 t (3.40 yd³)	3.44 t (5.09 yd³)
500 sq ft	2.29 t (3.40 yd³)	3.44 t (5.09 yd³)	4.58 t (6.79 yd³)	6.88 t (10.19 yd³)
1,000 sq ft	4.58 t (6.79 yd³)	6.88 t (10.19 yd³)	9.17 t (13.58 yd³)	13.75 t (20.37 yd³)
1,500 sq ft	6.88 t (10.19 yd³)	10.31 t (15.28 yd³)	13.75 t (20.37 yd³)	20.63 t (30.56 yd³)

Frequently Asked Questions

Multiply your project length (25 ft) by width (6 ft) to get area (150 sq ft). Multiply by depth in feet (3 in ÷ 12 = 0.25 ft) to get 37.5 cubic feet, then divide by 27 to get 1.39 base cubic yards. Adding a 10% ordering adjustment gives 1.53 yd³, which equals 1.03 US short tons at 1350 lb/yd³.

One cubic yard (27 cubic feet) of Volcanic Lava Rock (3/4" – 1-1/2" Scoria) weighs approximately 1,350 pounds, or 0.68 US short tons (50 lbs per cubic foot). Typical regional quarry densities range between 1,150 and 1,550 lb/yd³.

For most lava rock installations, a typical compacted depth is 3 inches (our default preset uses 3 inches). Always excavate soft organic topsoil and install woven or non-woven geotextile fabric before spreading aggregate.

At 0.68 tons per cubic yard, 1 US short ton equals 1.48 cubic yards (40.0 cu ft). That covers approximately 240 sq ft at 2" deep, 160 sq ft at 3" deep, and 120 sq ft at 4" deep.