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Calcimator

Blast Pattern Design Calculator

Calculate burden, spacing, hole depth, and powder factor for bench blasting operations.

Inputs

in
ft
lb/ft³

Results

Burden

13.5 ft

≈ 2 adult heights

Spacing16.3 ft
Hole Depth44.1 ft
Subdrill4.1 ft
Stemming9.5 ft
Charge Length34.6 ft
Tons per Hole726 t
Powder Factor0.68 lb/t
Explosive (lbs)496.79
How to Use This Calculator
  1. Enter hole diameter (mm) from your drill specifications.
  2. Set bench height (m) and rock density (t/m³) for your ore body.
  3. Select rock type: Soft, Medium, or Hard Rock — affects burden factor and spacing ratio.
  4. Review Burden (m), Spacing (m), and Stemming (m) for the blast pattern layout.
  5. Use Explosive charge per hole (kg) and Powder factor (kg/t) for explosive purchasing and regulatory reporting.

How the result changes with Hole Diameter

Hole DiameterBurden
3.36.9 ft
6.5513.6 ft
1020.8 ft
1429.2 ft

What each input means

Hole Diameter
Blast hole diameter in inches
Bench Height
Height of the bench face
Rock Density
In-situ rock density
Rock Type
General rock hardness classification

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Hole Diameter = 6.5, Bench Height = 40, Rock Density = 165, Rock Type = 1 = 4 input(s) provided
  2. Calculate Burden
    Burden
    13.5 = 13.5
  3. Calculate Spacing
    Spacing
    16.3 = 16.3
  4. Calculate Hole Depth
    Hole Depth
    44.1 = 44.1

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