Landscape Rock Calculator

Landscape Aggregate Metrology & Quarry Density Constants

Bulk rock and gravel materials are sold by volume (cubic yards) and weight (tons):

• **

• Quarry Density Table (Tons per Cubic Yard)**:

• Pea Gravel: 2,700 lbs/cu yd = 1.35 tons/cu yd

• Medium River Rock / Egg Rock (1"-3"): 2,600 lbs/cu yd = 1.30 tons/cu yd

• Crushed Granite / Decomposed Granite (DG): 2,800 lbs/cu yd = 1.40 tons/cu yd

• Crushed Limestone / Trap Rock (#57): 2,700 lbs/cu yd = 1.35 tons/cu yd

• Lava Rock / Volcanic Scoria (Lightweight): 1,400 lbs/cu yd = 0.70 tons/cu yd

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• Volume & Tonnage Formulas**:

Net Volume (cu ft) = Area (sq ft) × (Depth (in)12)

Gross Volume (cu yd) = (Net Volume (cu ft)27) ×

Total Tons = Gross Volume (cu yd) × Density

Bags (0.5 cu ft) = Gross Volume (cu ft) / 0.50

• **

• Standard Project Benchmarks (@ 10% Compaction)**:

• 200 sq ft Path (2" Pea Gravel): 1.36 cu yd | 1.83 Tons | 74 Bags (0.5 cu ft)

• 300 sq ft Bed (3" River Rock): 3.06 cu yd | 3.97 Tons | 165 Bags (0.5 cu ft)

• 400 sq ft Patio (4" Crushed Granite): 5.43 cu yd | 7.60 Tons | 294 Bags (0.5 cu ft)

How to Use This Calculator

Enter your Landscape Bed Length (e.g. 30 in ft), Landscape Bed Width (e.g. 10 in ft), Layer Depth / Thickness — choose from 2" Depth (Minimum Decorative Cover for Small Pea Gravel), 3" Depth (Standard Recommended for 1" to 3" River Rock), 4" Depth (Heavy Groundcover / Driveway / Weed Suppression), Rock Material & Density Type — choose from River Rock / Egg Rock (1"-3" - 1.30 tons / cu yd), Pea Gravel (3/8" - 1.35 tons / cu yd), Crushed Granite / Decomposed Granite (1.40 tons / cu yd), Settling & Compaction Allowance — choose from 0% (Exact Volume), 5% (Hard Ground / Bordered Edging), 10% (Recommended - Soil Settling & Uneven Grade), and Landscape Project Benchmark — choose from Custom Landscape Area, 30 × 10 ft Front Yard Bed (300 sq ft, 3" River Rock) → 3.06 cu yd / 3.97 Tons (121 Bags @ 0.5 cu ft), 50 × 4 ft Garden Pathway (200 sq ft, 2" Pea Gravel) → 1.36 cu yd / 1.83 Tons. Measure twice before entering dimensions — small measurement errors scale up significantly in material estimates.

The Formula

Formula Reference: Landscape Rock Calculator

Input variables:

gardenLengthFt — Landscape Bed Length

gardenWidthFt — Landscape Bed Width

rockLayerDepthInches — Layer Depth / Thickness

rockTypeDensitySelect — Rock Material & Density Type

compactionWasteSelect — Settling & Compaction Allowance

Computed outputs:

rockTonsRequired — Total Rock Weight Needed

volumeCubicYards — Bulk Volume (Cubic Yards)

halfCuFtBagsCount — Retail Bags (0.5 cu ft each)

fiftyLbBagsCount — 50 lb Bags (if sold by weight)

totalSquareFootage — Bed Surface Area

Mathematical relationships extracted from calculation logic:

area = length * width

tonsPerCuYd = 1.30; // River Rock (1"-3")

netCuFt = area * (depth / 12.0)

wasteMult = 1.0 + (wastePercent / 100.0)

grossCuFt = netCuFt * wasteMult

grossCuYd = grossCuFt / 27.0

totalTons = grossCuYd * tonsPerCuYd

bagsHalfCuFt = Math.ceil(grossCuFt / 0.50)

bagsFiftyLb = Math.ceil((totalTons * 2000.0) / 50.0)

weedFabricSqFt = Math.ceil(area * 1.10)

Reference constants:

tonsPerCuYd = 1.30

Standard: IRC / NAHB residential construction estimating standards

Worked Example

A homeowner landscaping a 30 × 10 ft garden bed with 3" of decorative river rock calculates that 3.06 cu yd (3.97 tons) is needed, choosing a bulk quarry delivery to save over 300 compared to purchasing 165 individual 0.5 cu ft bags.

Understanding Your Result

Construction estimates are starting points — site conditions, material specifications, and local code requirements will affect final quantities and costs. Always obtain at least three contractor bids for major projects. Local building departments can confirm permit requirements and inspection milestones. Add waste factors appropriate to the material type and complexity: 10% for simple rectangular shapes, 15–20% for complex geometries or custom cuts.