Data Source and Methodology
Authoritative source: Engineering ToolBox — Densities of common materials (2024). Direct link: engineeringtoolbox.com/density-materials.
All geometric calculations follow standard area and volume formulas. Bulk density defaults are derived from the ranges reported at the source above and are representative for typical construction gravels.
Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.
The Formula Explained
Total area A is the sum of each shape’s area A_i:
LaTeX: A = \sum_i A_i
Areas by shape:
LaTeX: A_{\text{rect}} = L \times W
LaTeX: A_{\text{circle}} = \pi \left(\frac{D}{2}\right)^2
LaTeX: A_{\text{annulus}} = \frac{\pi}{4}\left(D_o^2 - D_i^2\right)
LaTeX: A_{\text{triangle}} = \frac{1}{2} \times \text{base} \times \text{height}
Volume V is area times compacted depth d:
LaTeX: V = A \times d
Waste factor w (%) is applied multiplicatively:
LaTeX: V_{\text{adj}} = V \times \left(1 + \frac{w}{100}\right)
Weight W uses bulk density ρ:
LaTeX: W = V_{\text{adj}} \times \rho
Unit conversions:
LaTeX: 1~\text{yd}^3 = 27~\text{ft}^3,\;\; 1~\text{ft}^3 = 0.0283168466~\text{m}^3
LaTeX: 1~\text{short ton} = 2000~\text{lb},\;\; 1~\text{tonne} = 1000~\text{kg}
Glossary of Variables
Units: Imperial (ft, in, lb, ton) or Metric (m, cm, kg, tonne).
L, W: Length and Width for rectangles.
D: Diameter for circles; Dₒ and Dᵢ for outer and inner diameters in annuli.
base, height: For triangles.
d: Compacted depth or thickness layer.
ρ (density): Bulk density of gravel, mass per unit volume.
w: Waste factor (%), extra volume for contingencies.
Area: Total surface covered by gravel.
Volume: Gravel volume needed before/after waste factor.
Weight: Estimated total mass based on density.
Bags: Approximate count of 50‑lb or 25‑kg bags.
How It Works: A Step-by-Step Example
Suppose you are resurfacing a 30 ft by 10 ft driveway with 4 inches of compacted crushed stone (compacted). Choose Imperial, add a Rectangle area with L=30 ft and W=10 ft. Depth d=4 in = 0.333 ft. Area A = 30 × 10 = 300 ft². Volume V = 300 × 0.333 = 99.9 ft³ = 3.70 yd³. With w = 5%: V_adj = 3.70 × 1.05 = 3.89 yd³. Using ρ ≈ 100 lb/ft³, weight W = 99.9 ft³ × 100 lb/ft³ × 1.05 ≈ 10,490 lb = 5.25 US tons. Bag estimate: 10,490 ÷ 50 ≈ 210 bags of 50 lb, or ≈ 190 bags of 25 kg.
Frequently Asked Questions (FAQ)
How accurate are the results?
Geometric calculations are exact, but density and installation methods vary. Use site-specific density and include adequate waste to improve accuracy.
Should I enter loose or compacted depth?
Enter the compacted thickness you want as the finished layer. If you measure loose depth, increase it to account for compaction.
Why do my tons differ from the supplier’s quote?
Suppliers may use different densities for their specific aggregates. Ask them for the assumed bulk density and adjust the calculator accordingly.
Can I change units after entering values?
Yes. Switching units updates labels and conversions. Always review inputs after switching to ensure they reflect your intent.
What about layered systems (base + top course)?
Calculate each layer separately with its own depth and density, then sum the results for total ordering quantities.
Do I need edge restraints or geotextile?
These items are outside volume calculations but impact performance. Follow local codes and manufacturer guidance.