In-Situ Testing & Geophysics
SPT N-Value Correction Calculator
Automatically correct raw Standard Penetration Test (SPT) blow counts to standard (N1)60 values used for design by applying overburden, energy, and sampler corrections.
SPT N-Value Correction Calculator
Automatically correct raw Standard Penetration Test (SPT) blow counts to standard (N1)60 values used for design by applying overburden, energy, and sampler corrections.
Inputs
Test Parameters
Correction Factors
Auto~80%, Safety~60%, Donut~45%
Length above ground level
Results
Results
Theory and formulae
Correction Formulations
About this calculator
This free spt correction calculator runs entirely in your browser: what you enter is never uploaded. Use the calculation steps and the theory section to check the working, and print a calculation sheet with the inputs, results and formulae for your records.
Methods and references: ASTM D1586, Liao and Whitman 1986.
Topics: spt, n-value, correction, n60, n160, in-situ, penetration.
Engineering notice: Results are for preliminary estimation, screening and education. All inputs and outputs must be independently verified by a qualified professional engineer before use in any design or construction decision. Read the full disclaimer
Disclaimer
This calculation sheet was generated with Geotechnical Toolbox for preliminary estimation, screening, educational and verification purposes only. Geotechnical engineering involves site-specific ground conditions and uncertainty. All inputs, methods, results and figures must be independently checked and approved by a qualified Professional Engineer (P.Eng. / PE) before being relied on for design, construction or any safety-critical decision. Results reflect the values entered at the time of printing. The author and site accept no liability for errors, omissions or damages arising from their use.
Open this calculator online: geotechnica.ca/tools/spt-correction
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