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Gradistat v91 is a version of Gradistat, a software package used for grain-size distribution analysis and sedimentology. It provides tools for importing sediment data (phi or millimeter units), computing descriptive statistics (mean, median, mode, standard deviation, skewness, kurtosis), performing graphical outputs (histograms, cumulative curves, probability plots), and applying standard grain-size sorting models (Folk & Ward, graphical methods). v91 denotes a release with incremental feature updates and bug fixes over previous builds.
Because the original v 9.1 is no longer supported, the geoscience community has created "forks" and improvements:
If you need a pure free experience but want modern stability, the Gradistat 9.1 macro can still be copied to a new .xlsm file – an advanced but doable project. gradistat v 91 free
Gradistat v 9.1 is free, but it has limitations: no 64-bit Excel support, no automatic batch processing, and it can be unstable on modern Windows 11 with newer Excel. Here is how it stacks up:
| Feature | Gradistat 9.1 Free | Gradistat (commercial successor) | GSlope | R package ‘G2Sd’ | | --- | --- | --- | --- | --- | | Price | Free | Paid (~$100-200) | Free | Free | | GUI | Excel-based | Standalone | Standalone | Command-line | | Batch processing | No | Yes | Yes | Yes | | Hydrometer support | Yes | Yes | No | Limited | | Modern OS support | Partial (Windows only) | Full | Full | Cross-platform | | Learning curve | Low | Low | Medium | High | Gradistat v91 is a version of Gradistat, a
Verdict: Gradistat 9.1 remains best for students, quick analyses, and legacy data compatibility. For large-scale research (>100 samples), consider a modern tool.
GradiStat v9.1 Free is a no-frills, deterministic tool designed for one thing: univariate gradient analysis (specifically, calculating the statistical optimum and tolerance of species along an environmental gradient). If you are a paleontologist or ecologist needing to replicate a 1990s transfer function, this is gold. If you expect graphs, intuitive data handling, or any support for multivariate analysis, look elsewhere. If you need a pure free experience but
1. Laser Focus on Univariate Optima The core algorithm (often based on Gaussian logit regression) is surprisingly robust. For calculating where a species really peaks along a single gradient (e.g., pH, depth, temperature), v9.1 outperforms many bloated modern suites. It handles skewed distributions better than simple weighted averaging.
2. Truly Free & Portable No license. No online activation. The entire program often runs off a USB stick. For fieldwork or working on ancient lab computers, this is a lifesaver.
3. Deterministic & Transparent Unlike black-box machine learning, GradiStat shows you the iteration steps. You can literally see the log-likelihood converging. For teaching gradient analysis concepts, this transparency is invaluable.
You can input data in multiple formats: