ToolsRock MechanicsRock Strength Testing

Sonic UCS Estimator

Estimate rock UCS from P-wave velocity using three correlations. Enter velocity directly or from path length and transit time. Includes UPV quality grading per BS EN 12504-4.

Last updated 19 May 2026

About this tool

Estimate rock UCS from ultrasonic P-wave velocity measurements. Enter velocity directly or calculate it from path length and transit time. Three published correlations give a range of strength estimates.

Also grades the rock quality from velocity per BS EN 12504-4 (Excellent to Very Poor). Useful for rapid non-destructive assessment of rock material quality in the field or lab.

Standards: BS EN 12504-4 (UPV testing), ISRM Suggested Methods.

How to use this tool

1. Enter velocity directly — in m/s, or enter path length (mm) and transit time (µs) to calculate it.

2. Read the quality grade and UCS estimates — three correlations give a range to inform judgement.

Technical information

Sharma & Singh (2008): UCS = 0.0642 × Vp - 117.99 (Vp in m/s)

Kahraman (2001): UCS = 9.95 × Vp^1.21 (Vp in km/s)

Tugrul & Zarif (1999): UCS = 35.54 × Vp - 55 (Vp in km/s)

Quality grades: >4.5 km/s Excellent, 3.5–4.5 Good, 3.0–3.5 Doubtful, 2.0–3.0 Poor, <2.0 Very Poor.

Limitations

P-wave velocity is affected by porosity, saturation, microcracks, anisotropy, and temperature. Correlations have significant scatter.

The Sharma correlation can give negative UCS for low velocities (<1800 m/s). The tool clamps these to zero.

Revision history

19 May 2026: Initial release

Disclaimer

This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.

Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.

All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.

By using this tool, you accept full responsibility for how you interpret and apply the information provided.

Spotted an error? Let us know.

Enter velocity directly OR path length + transit time.

P-wave velocity (m/s)

Path length (mm)

Transit time (µs)

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