Fragmentation P80 Estimator (Kuz-Ram)
Estimates blast fragment sizes P80 and X50 using the Kuz-Ram model and rock factor.
Enter Values
Minimum 0
Minimum 0
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter the rock factor A, volume per hole, charge per hole and explosive RWS.
- Press Calculate.
- Read the mean fragment size and estimated P80.
How it works
Uses the Kuz-Ram model: the Kuznetsov equation gives the mean fragment size (X50); the P80 is estimated with a Rosin-Rammler uniformity index.
Worked example
Typical bench blast. Returns an estimated mean and P80 fragment size in centimetres.
Frequently asked questions
How reliable is Kuz-Ram?
It's a well-known estimate, not a guarantee — actual fragmentation depends on rock structure, timing and accuracy. Use it for comparison and planning.
Related tools
- Powder Factor Calculator (kg per BCM)
- Blast Timing Delay Calculator
- Blast Pattern Designer
- Bench Height Checker
- Blast Area Calculator
- Blast Hole Count Checker
Explore more in Mining, Quarry, Earthworks, Drill & Blast.
Cite this tool
Zerdly. (2026). Fragmentation P80 Estimator (Kuz-Ram). Retrieved from https://www.zerdly.com/tools/fragmentation-p80-estimator-kuz-ram/
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.