Fragmentation P80 Estimator (Kuz-Ram)
A free, browser-based calculator. Runs entirely in your browser — no sign up, nothing stored.
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Enter Values
Enter your values and press Calculate to see results.
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
Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.