If you've ever spent hours manually calculating grain size parameters, you know how laborious the process can be. Whether you are working with traditional sieve data or modern laser granulometry, having a reliable automated tool is essential. Enter GRADISTAT, the industry-standard software developed by Simon Blott and Kenneth Pye. What is GRADISTAT?
GRADISTAT is an integrated package for Microsoft Excel that automates the calculation of grain size statistics from unconsolidated sediments. While older versions like v8.0 were designed for Excel 2010, researchers have frequently utilized updated iterations for modern workflows. Key Features and Capabilities
The program is designed for speed, capable of processing approximately 50 samples per hour. Its core functionality includes:
Statistical Methods: It calculates mean, mode, sorting, skewness, and kurtosis using both the Method of Moments and the Folk and Ward graphical methods.
Versatile Units: Statistics are provided in metric units (arithmetically/geometrically) and phi units (logarithmically).
Physical Descriptions: Beyond numbers, it assigns descriptive sediment textures based on the Folk (1954) classification and the Wentworth (1922) size scale.
Graphical Output: The software automatically generates frequency plots and ternary diagrams to visualize sediment composition. Why Researchers Choose GRADISTAT
While other specialized packages exist, GRADISTAT remains popular due to its:
Integration: Running entirely within Excel allows for seamless data transfer and familiar formatting.
Robustness: Folk and Ward measures in metric units provide a highly stable basis for comparing compositionally variable sediments.
Flexibility: It accepts both standard and non-standard size data from various measuring techniques like X-ray sedigraphs and Coulter counters. How to Get Started
You can find the software and full instructions through the Kenneth Pye Associates Ltd (KPAL) software portal. The "original" versions are often hosted on academic repositories and the Earth Surface Processes and Landforms (ESPL) website.
For those looking for even more modern functionality, a fully revised version known as GRADISTAT-PRO is currently in development to offer greater functionality for modern research environments. GRADISTAT software - Kenneth Pye Associates Ltd
Here are some of the good features of Gradistat v9.1 (free version) , which is widely used for grain size analysis and sedimentology:
Comprehensive Statistical Parameters
Calculates Folk & Ward (1957) graphical measures: mean, sorting, skewness, and kurtosis, plus moment measures (after Friedman, 1962).
Multiple Graphical Outputs
Generates cumulative curves, histograms, and frequency plots directly from entered grain size data.
Flexible Data Input
Accepts phi or mm intervals, and allows up to 100 size classes. Data can be entered manually or imported from spreadsheets.
Graphical & Method Comparison
Compares results from different statistical methods (e.g., inclusive graphical vs. moment) within the same interface.
No Installation Required (Portable)
The free version runs as a standalone executable – no complex setup, registry changes, or dependencies.
User-Friendly for Students & Researchers
Simple step-by-step workflow: input % weights per sieve/class → choose method → click “Calculate” → view statistics and plots. gradistat v 91 free
Educational Utility
Widely used in university sedimentology labs because the free version clearly shows intermediate calculations, helping learners understand grain size statistics.
Lightweight & Fast
Very small file size (a few MB), runs instantly even on older Windows systems (compatible with Windows 95 up to Windows 10 via compatibility settings).
⚠️ Note: The original free version (v9.1) is no longer officially supported by the author (S.J. Blott), but the classic freeware is still available from archive sources. For modern OS, you may need to run it in compatibility mode.
Analysis of GRADISTAT v. 9.1: A Standard in Sedimentological Computing
GRADISTAT is a widely utilized grain size distribution and statistics software package specifically designed for the analysis of unconsolidated sediments. Originally developed by Dr. Simon J. Blott and published in 2001 alongside Kenneth Pye, the program has become a cornerstone tool for researchers in geomorphology and sedimentology due to its accessibility and comprehensive analytical capabilities. 1. Software Overview and Architecture
Unlike standalone specialized software, GRADISTAT is built as a Microsoft Excel macro, which allows for a high degree of versatility and ease of use within a familiar spreadsheet environment. It is designed to handle data from various measuring techniques, including: Sieve Analysis: Manual weighing of sediment fractions. Laser Granulometry: Modern light diffraction methods.
Other Methods: Including X-ray sedigraph and Coulter counters.
The program enables the rapid processing of samples—averaging approximately 50 samples per hour—calculating complex statistics that would otherwise be laborious to perform manually. 2. Key Statistical Capabilities
GRADISTAT provides a robust suite of statistical measures calculated through multiple methodologies:
Methods of Calculation: It supports both the Method of Moments (arithmetic and geometric) and the Folk and Ward (1957) graphical methods.
Output Parameters: The software calculates essential descriptors such as mean, mode, sorting (standard deviation), skewness, and kurtosis.
Scaling: Results are provided in both metric units (micrometers) and logarithmic phi units.
Classification: It automatically assigns descriptive terms based on calculated statistics, such as sediment names following the Folk (1954) classification system. 3. Visual and Graphical Output
A primary advantage of GRADISTAT is its ability to generate professional-grade graphical outputs directly within Excel. Users can produce: GRADISTAT software - Kenneth Pye Associates Ltd
A common point of confusion: Is Gradistat v 9.1 really free? And where can you download it safely today?
Official Status: The original website (www.kpal.co.uk) no longer hosts the software. The developers have retired or moved on. However, the software was released as freeware for academic and non-commercial use. No one currently holds exclusive distribution rights, but the original license remains in force.
Safe Download Sources (as of 2025-2026):
sedipt, geostats). Look for a .xls (not .xlsx) file, as macros require the old format.edu "gradistat 9.1".xls file as a supplementary resource.⚠️ Important Warning: Never download Gradistat from untrusted "crack" or "serial key" websites. The software is free – anyone charging for it is scamming you. Always scan downloaded .exe or .xls files for malware (though the original is a simple macro workbook).
If you want, I can draft a short methods paragraph formatted for a manuscript stating exactly how to report analyses done with Gradistat v91 (including example phrasing and citation). If you've ever spent hours manually calculating grain
Gradistat Version 9.1 is a powerful, Excel-based software program designed for the rapid analysis of grain size statistics. It has become an industry standard for geologists, hydrologists, and environmental scientists who need to process sediment data efficiently.
If you are looking for a reliable way to calculate particle size distributions without the complexity of high-end specialized software, this tool is the perfect solution. What is Gradistat v 9.1?
Developed originally by Simon Blott, Gradistat was created to automate the tedious calculations involved in sedimentology. It functions as an Add-In for Microsoft Excel, making it highly accessible for students and professionals alike. The program accepts data from various methods, including: Sieve analysis Laser diffraction (such as Malvern or Beckman Coulter) Pipette and hydrometer methods Key Features and Capabilities
Gradistat v 9.1 provides a comprehensive suite of statistical outputs based on both the Folk and Ward method and the Method of Moments. When you process your data, the software automatically generates:
Statistical Parameters: Mean, mode, sorting (standard deviation), skewness, and kurtosis.
Textural Classification: Descriptive terms based on the Folk and Ward scale (e.g., "Very Fine Sand").
Physical Descriptions: Classification into groups like "Sandy Mud" or "Slightly Gravelly Sand" using the modified Udden-Wentworth scale.
Visual Data: Automatic generation of cumulative frequency curves and histograms. Why Use Version 9.1?
While earlier versions of Gradistat were revolutionary, Version 9.1 includes several refinements that improve compatibility with modern versions of Microsoft Excel.
Improved Macro Stability: Optimized code reduces crashes when handling large datasets.
Broader Classification: Enhanced logic for defining sediment types in complex mixtures.
Export Options: Easier ways to move your graphs and tables directly into reports or thesis documents. How to Get Gradistat v 9.1 Free
The best part about Gradistat is that it is typically distributed as "freeware" for academic and non-commercial use. Researchers and students can usually find the official download through university repositories or the author's academic affiliations. Installation Steps:
Download the File: Usually provided as a .zip containing an .xla or .xlsm file.
Enable Macros: Since Gradistat runs on VBA, you must "Enable Content" when opening the file in Excel.
Input Data: Paste your sieve weights or percentage data into the designated input sheet.
Calculate: Click the "Calculate" button to populate the results sheets automatically. System Requirements To run Gradistat v 9.1 smoothly, you simply need:
A PC or Mac capable of running Microsoft Excel (2010 or newer recommended).
Basic knowledge of grain size intervals (microns or phi units). Macros enabled in your Excel security settings. the features remain powerful and relevant:
📍 Key Takeaway: Gradistat v 9.1 remains the most cost-effective and user-friendly tool for sedimentological analysis. It bridges the gap between manual spreadsheets and expensive proprietary software.
If you'd like to find a direct download link or need help troubleshooting a specific error message in Excel: Tell me your Excel version (e.g., Office 365, Excel 2019) Specify your operating system (Windows or Mac)
I can then provide specific instructions to get the software running on your machine.
GRADISTAT is a widely used software package designed for the rapid analysis of grain size statistics from unconsolidated sediments. Originally developed by Simon J. Blott and Kenneth Pye, it operates as an integrated macro within Microsoft Excel, making it highly accessible for researchers in geomorphology and sedimentology.
While users often search for "GRADISTAT v 9.1," it is important to note that official versions listed by the developers typically include Version 4.0, 8.0, and a newer "GRADISTAT-PRO" currently under development. References to "v 9.1" may stem from the software's historical compatibility with older Excel versions (like Excel 2000, also known as version 9.0) or confusion with other statistical packages like STATISTICA 9.1. Key Features of GRADISTAT
GRADISTAT automates the calculation of essential sedimentological statistics, allowing researchers to process approximately 50 samples per hour.
Statistical Methods: It calculates mean, mode, sorting (standard deviation), skewness, and kurtosis using both the Method of Moments and the Folk and Ward (1957) graphical methods.
Versatile Input: The program accepts data from various measuring techniques, including traditional sieving, laser granulometry, X-ray sedigraphs, or Coulter counters.
Multi-Scale Output: Statistics are provided in both metric units (micrometers) and logarithmic phi units.
Graphical Tools: GRADISTAT generates a range of visual outputs, including frequency histograms, cumulative distribution curves, and ternary (triangular) plots. How to Download GRADISTAT for Free
GRADISTAT is generally available as a free download for academic and research purposes through official and institutional channels:
Kenneth Pye Associates Ltd (KPAL): The official KPAL website provides downloads for original versions and Version 8.0 (compatible with Excel 2000–2010).
Academic Repositories: You can often find the software and its documentation on platforms like Zenodo or linked through the original research paper published in Earth Surface Processes and Landforms.
Modern Alternatives: For those using R, the G2Sd package is a free, open-source evolution of the GRADISTAT v. 4.0 macro, designed for modern statistical environments. Why Use GRADISTAT?
Before this software, calculating complex statistics for large datasets was a laborious manual process. GRADISTAT simplifies this by providing robust, standardized descriptive terms (e.g., "very well sorted" or "fine skewed") based on recognized sedimentological scales. This standardization is crucial for mitigating coastal erosion, managing floods, and conducting environmental impact studies. GRADISTAT software - Kenneth Pye Associates Ltd
Disclaimer: GradiStat v9.1 is an older, freeware software package (often distributed via academic archives). This review reflects its functionality as a classic tool, not a modern cloud-based application.
You can input data in multiple formats:
The software computes up to 14 statistical parameters using three different methods:
Even though it is "old" software, the features remain powerful and relevant: