Pre‑Split Blasting Calculator

About the Pre‑Split Blasting Calculator

Pre‑split blasting creates a clean tensile fracture plane that protects final pit walls and cut slopes from overbreak. This calculator helps drill‑and‑blast teams size their explosive columns and hole spacing correctly by applying the standard split‑factor formula

Where;

Mh = Mass of Explosives per metre in the hole (kg/m)

S = Hole Spacing (m)

P = Split Factor (kg/m2)

Enter your hole diameter, spacing, split factor or powder factor, and the calculator returns:

Charge mass per hole and per metre
Total explosive mass for the pre‑split line
Recommended decoupling ratio and uncharged length

The output lets you check designs against the rules of thumb from Chiappetta, Tose, Dyno Nobel and Konya, adjust for rock type, and hit stability and cost targets first time. For a deeper dive into best practice, see our detailed article on pre‑split design and optimisation, or contact our engineers for site‑specific support.

Common Pre-Split Challenges & Solutions

Damaged Crest
For crest damage after pe-splitting, look for excessive heave post-blast, look for overmining of pre-split line during bench-prep and/or production loading, review the stemming design used, review split factor and cartridge diameter for excessive energy, and finally, review actual charge height (height of final cartridge)

Toes on Face

For Toes on the face after pre-splitting, review charging methodology to ensure cartridges are placed at the toe of the hole, review drilling compliance to ensure correct drilling practices, review number of cartridges used at the toe of the hole, and finally, review the buffer row design and quality of execution.

Excessive Backbreak

For excessive Back Break after pre-splitting, review the split factor used, review the cartridge size used, review the hole diameter and spacing used, review the buffer stand-off, buffer design and timing design, and finally, review the design and quality of the execution of trim blasts.

Excessive Airblast

For excessive Airblast induced by Pre-splitting, review the split factor used, review the cartridge size used, review the hole diameter used, review the stemming design used, review the total number of holes blasted instantaneously. In sensitive areas pre-split holes should be batched to fire in groups of 5 holes or 10 holes at a time depending on the severity of sensitivity of the environment where blasting is taking place. Alternative solutions like Line Drilling can also be pursued if pre-split blasting is continuing to pose Airblast risk.

If your challenge is not in the list above, reach out to our Engineers for assistance.