What is a typical powder factor for hard rock mining?

Hard rock blasting typically requires 0.2–0.5 kg of explosive per tonne of rock. Soft rock or coal may need as little as 0.05–0.15 kg/t, while highly competent granite or basalt can require 0.4–0.6 kg/t or more.

What is the difference between kg/t and kg/m³ powder factor?

Powder factor expressed in kg/t (per tonne) accounts for rock density variation and is preferred for ore planning. Powder factor in kg/m³ (per cubic meter) is common in quarrying and civil excavation where volume is the billing unit. To convert: kg/m³ = kg/t × rock density (t/m³).

How does powder factor affect fragmentation?

A higher powder factor generally produces finer fragmentation, which can improve downstream crusher efficiency but increases explosive cost. A lower powder factor may leave oversize boulders that require secondary breakage. The optimum balances fragmentation targets with cost.

Why does my powder factor differ from the design value?

Actual powder factor can deviate from design due to misfires (unfired holes reduce total explosive mass), hole collapse reducing charge length, or inaccurate blast volume measurement. Always reconcile actual explosive loaded against the surveyed muck volume.

Can I use this tool for underground blasting?

Yes. Enter the total explosive mass per blast round and the tonnage or volume broken. Underground development blasts typically run 0.3–1.2 kg/t due to the confined geometry; stope blasts tend to be lower (0.15–0.4 kg/t) because the free face allows better energy utilization.

Blast Powder Factor Calculator

Name: Blast Powder Factor Calculator
Availability: InStock
Author: Nham Vu

Calculate the powder factor for blast design — kilograms of explosive per tonne or cubic meter of rock blasted.

Blast Parameters

Total Explosive Loaded (kg)

Rock Quantity Mode

Total Rock Mass (tonnes)

Rock Density (t/m³) — for cross-unit conversion

Granite ≈ 2.6–2.7 | Limestone ≈ 2.3–2.7 | Basalt ≈ 2.8–3.1

Results

Enter blast parameters and click Calculate.

Typical Powder Factor Ranges (kg/t)

Rock / Application	Typical Range (kg/t)	Notes
Coal / soft sedimentary	0.05 – 0.15	Low density, naturally fractured
Limestone / sandstone	0.12 – 0.30	Medium-strength sedimentary
Granite / basalt	0.25 – 0.55	Hard, massive igneous
Quartzite / taconite	0.40 – 0.70	Very hard, abrasive
Underground development	0.30 – 1.20	Confined geometry, single free face

Summary

Calculate the powder factor for blast design — kilograms of explosive per tonne or cubic meter of rock blasted.

How it works

Enter the total mass of explosive loaded in the blast (kg).
Choose whether to calculate per tonne of rock or per cubic meter.
For the per-tonne mode, enter the total rock mass (tonnes); for per-volume mode, enter the total blast volume (m³).
Optionally enter rock density to convert between tonne-based and volume-based results automatically.
The tool computes powder factor and displays equivalent values in both kg/t and kg/m³.

Use cases

Estimate explosive consumption for a production blast pattern in an open-pit mine.
Compare powder factors across blast rounds to identify fragmentation issues.
Benchmark blast efficiency against industry standards for a given rock type.
Convert between kg/t and kg/m³ powder factor when switching reporting units.
Validate drill-and-blast designs against target fragmentation requirements.
Calculate total explosive cost per tonne of ore or waste material.

Frequently Asked Questions

Last updated: 2026-07-01 · Reviewed by Nham Vu