Blasting Powder Factor Calculator

Work out blasting powder factor instantly with clear inputs, formula shown and shareable results.

About Blasting Powder Factor Calculator

Powder factor is explosive mass per unit of rock broken, usually kilograms per tonne. Typical values are 0.15-0.30 kg/t for soft rock and 0.4-0.8 kg/t for hard competent rock. It is the primary control on fragmentation, and under-charging shifts cost downstream into crushing and grinding energy.

Formulas

Powder factor

PF (kg/t) = explosive mass / (rock volume x rock density)

Volume basis

PF (kg/m3) = explosive mass / rock volume

Worked example

With the default values below, Blasting Powder Factor Calculator returns Powder Factor of 0.26415. Change any input above and every figure here is recalculated in your browser.

Inputs used

Explosive Chargedminimum 0 kg: 4,200 kg
Rock Volume Blastedminimum 0 m3: 6,000 m3
Rock Densityminimum 0.01 t/m3: 2.65 t/m3
Explosive Costminimum 0 per kg: 85 per kg

Results

Powder Factor: 0.26415
Powder Factor Per Cubic Metre: 0.70000
Rock Blasted: 15,900.0
Explosive Cost Per Tonne: $22.453

Step by step

1Values used
2Powder factor
3Volume basis
4Powder Factor= 0.26415
5Powder Factor Per Cubic Metre= 0.70000
6Rock Blasted= 15,900.0
7Explosive Cost Per Tonne= 22.453

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 5 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Explosives storage, transport and use are strictly regulated and must be carried out by licensed shotfirers under an approved blast design, with vibration and flyrock controls.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Explosives storage, transport and use are strictly regulated and must be carried out by licensed shotfirers under an approved blast design, with vibration and flyrock controls.

Frequently Asked Questions

Is a low powder factor good?

Not necessarily. Explosive energy is the cheapest way to break rock; skimping produces coarse muck that costs far more to crush and grind. Optimise total mine-to-mill cost, not blasting cost alone.

What else does powder factor affect?

Fragmentation, muckpile diggability, wall damage, flyrock, ground vibration and airblast. Raising it to improve fragmentation must be balanced against vibration limits near sensitive structures.