How to Measure Particle Size in ImageJ (SEM/TEM) | Step-by-Step Feret Diameter Guide
Learn the correct, automated method to measure particle size in ImageJ from SEM or TEM images. In this step-by-step tutorial, Dr. Ranjana Varma from InSciLabTech demonstrates scale calibration, thresholding, Feret’s diameter measurement, and histogram generation for publication-ready size distribution analysis.
This updated workflow replaces manual measurement with a faster, objective, and statistically reliable method using ImageJ (Fiji).
🔬 What You’ll Learn
00:00 – Introduction
01:13 – Opening your SEM/TEM image in ImageJ
01:40 – Setting the scale using the scale bar (pixel to micrometer conversion)
02:31 – Converting to 8-bit grayscale for particle analysis
02:55 – Selecting Region of Interest (ROI)
03:14 – Proper thresholding to isolate particles
04:04 – Setting measurements (Area & Feret’s Diameter)
05:04 – Analyze Particles settings (removing noise & edge particles)
05:45 – Exporting results as CSV
05:56 – Creating a histogram in Origin (µm to nm conversion included)
08:26 – Exporting publication-ready graphs
🔎 Frequently Asked Questions
How do I measure particle size in ImageJ?
Set the scale using the image scale bar, convert to 8-bit, apply threshold, use Analyze Particles, and measure Feret’s diameter or area.
What is Feret’s diameter in ImageJ?
Feret’s diameter is the maximum distance between two parallel tangents of a particle. It is ideal for irregularly shaped particles.
How many particles should I measure for reliable statistics?
For meaningful size distribution analysis, measuring at least 100–200 particles is recommended.
Can this method be used for grain size analysis?
Yes. The same workflow applies to grain size measurement, nanoparticle analysis, and porosity studies from SEM or microscopy images.
🧪 Why Use Feret’s Diameter?
For non-spherical or elongated particles, Feret’s diameter provides a more realistic particle size compared to assuming circular geometry. For perfectly spherical particles, equivalent circular diameter can also be calculated using area measurements.
💻 Software Used
-ImageJ (Fiji distribution – free)
-Origin (for histogram plotting; Excel or other software can also be used)
📌 Related Tutorials
How to Plot Histogram in Origin
XRD, SEM, TEM, XPS Explained
Research Software Tutorials for Materials Science
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