Dropometer
US$4,990 base kit, checked 23 October 2026
Contact angle goniometer comparison
DIY ImageJ vs Dropometer
ImageJ can measure a contact angle from a drop image for free, using a plugin such as DropSnake, LB-ADSA or the Contact Angle plugin. What it cannot give you is the camera, light, stage and dosing around that image. This page compares a DIY ImageJ setup with the Dropometer, an integrated kit, on cost, accuracy, time and what each can measure.
VS
DIY ImageJ setup
Free software; camera and rig from about US$20 to US$1,000 (OpenDrop authors), checked 23 October 2026
Written by
Abhimanyu Bhandankar
Holds an MBA from Schulich School of Business and a BE in IT. He joined Droplet Lab in July 2019 and now leads sales and marketing.
CEO at Droplet Lab
Read More
Technical Review by
Gurdeep Singh Saini
Holds a BASc in Mechanical Engineering from Ryerson University (now Toronto Metropolitan University) and an MASc from York University. He develops the automatic edge and baseline detection behind the Dropometer's analysis.
COO at Droplet Lab
Read More
The short answer
For a few static contact angles a year, a DIY setup with a free ImageJ plugin is the cheaper and sensible choice. For routine measurement, several operators, or surface tension and surface energy as well, the Dropometer (US$4,990) is the better buy: one kit, automatic edge and baseline detection, and 0.35° accuracy checked against a KRÜSS DSA100E in peer review.
When DIY ImageJ is the better choice
- Budget is the hard limit. ImageJ and the contact angle plugins cost nothing to download.
- You teach the method. DropSnake and LB-ADSA show the drop profile, baseline and fit, so students see how the analysis works.
- You measure rarely. A few static angles on flat, clean samples do not justify an instrument.
- You want to cite the algorithm. Both EPFL plugins are described in peer reviewed papers by Stalder and colleagues.
When the Dropometer is the better choice
- Several people measure. Automatic edge and baseline detection gives the same reading from the same image, whoever runs it.
- You need a stated accuracy. 0.35° for contact angle, checked against a KRÜSS DSA100E in two peer reviewed papers.
- You need more than static angle. Advancing and receding angles, pendant drop surface tension up to 75 mN/m and surface free energy in one app; sliding angle with the optional US$700 tilt stage.
- You measure off the bench. It runs on battery for up to 8 hours and analyses offline on the included phone.
- You want support. 5 year warranty and 5 years of software updates.
When not to buy a Dropometer
- You measure a handful of static angles a year and already own a camera and light: the free plugins will do.
- You teach drop shape analysis and want students to see every fitting step: ImageJ shows the method openly.
- You need contact angles below 10° or above 175°: that is outside the Dropometer's stated range.
- You need audit trails or electronic signatures: the Dropometer does not support them today.
Executive summary
ImageJ is image analysis software. A contact angle plugin fits the drop profile in a picture you supply, so the result depends on how that picture was taken. The Dropometer is a measurement system: phone camera, LED backlight, stage, syringe and analysis app sold as one kit, so the capture geometry is the same every time. New to the method? Our contact angle measurement guide covers the basics.
Where they overlap
Both measure static contact angle on a sessile drop from a side view image of the droplet.
Both fit the drop profile with established models: polynomial and Young–Laplace on the Dropometer; snakes, ellipse, sphere approximation or LB-ADSA in ImageJ.
Both can estimate surface tension from drop shape: LB-ADSA in ImageJ for sessile drops, the pendant drop method on the Dropometer.
Where they differ and why it matters
What you are buying
ImageJ is free analysis software for images you take yourself. The Dropometer is a US$4,990 kit that takes the image, doses the drop and analyses it.
Who sets up the image
In a DIY setup you choose the camera, lens, lighting, levelling and focus every time. The Dropometer fixes the camera to stage geometry and the backlight, so each image is taken the same way.
How the angle is found
Most ImageJ plugins need you to mark points, set the baseline or start the fit by hand. The Dropometer detects the drop edge and baseline automatically, then fits Young–Laplace or polynomial models.
What else you can measure
ImageJ covers static angle and, with LB-ADSA, a surface tension estimate. The Dropometer adds dynamic angles, pendant drop surface tension, surface free energy and, with the tilt stage, sliding angle.
A deeper look at the criteria that decide it
How the ImageJ route works
Download ImageJ or Fiji, then add a contact angle plugin: copy the plugin files into the plugins folder (DropSnake and LB-ADSA ship together as Drop_Analysis) and restart. Open a drop image, set the scale, place points on the drop profile and the baseline, and the plugin calculates the contact angle into a results table. The Contact Angle plugin by Marco Brugnara uses sphere or ellipse approximation and was last updated in 2006; its sphere model suits drops up to about 3 to 5 µL. DropSnake fits a snake to the drop edge; LB-ADSA fits the Laplace equation and also returns surface tension. The EPFL page recommends ImageJ 1.46, because the Drop_Analysis plugins have problems above version 1.47.
The real cost of free software
The plugin costs nothing; the measurement setup does not. You need a camera with a macro or zoom lens, an even backlight, a level stage and a way to place a drop of known volume. The OpenDrop authors put the camera alone at about US$20 to US$1,000 depending on the application. Then comes the time to build, align and check the rig against a known surface.
Operator to operator agreement
In a manual workflow each person picks the lighting, focus, baseline and fit points. Those choices move the result, which is why two people can read different angles from similar drops. The Dropometer's automatic edge and baseline detection gives the same reading from the same image. For multi person labs that matters more than the price. See our contact angle measurement guide for the main sources of scatter.
Where ImageJ is genuinely better
The ImageJ methods are published, so you can see exactly how each plugin fits the drop and cite it. That is valuable in teaching and in method development. It has no vendor lock in, runs on any computer, and LB-ADSA handles both contact angle and surface tension from the same image. If you are learning, start there; our lowest budget buying guide lists other low cost options.
Specification and capability matrix
| Criterion | DIY ImageJ setup | Dropometer |
|---|---|---|
| What it is | Free analysis software plus a camera rig you build | Integrated kit: phone camera, LED backlight, stage, syringe and app |
| Price (checked 23 October 2026) | Software free; camera about US$20 to US$1,000 (OpenDrop authors) | US$4,990 base kit, phone and lifetime licence included |
| Static contact angle | Contact Angle plugin, DropSnake, LB-ADSA | Young–Laplace and polynomial fits |
| Edge and baseline | Manual or semi automatic; you mark points or start the fit | Automatic edge and baseline detection |
| Stated accuracy | Not stated for a DIY setup; depends on your optics | 0.35° vs a KRÜSS DSA100E (peer reviewed); 0.01° resolution |
| Contact angle range | Depends on the plugin and image | 10° to 175° |
| Advancing and receding angles | From video, frame by frame, by hand | In the app |
| Sliding angle | Needs a tilt stage you build | Optional tilt stage, US$700 (0° to 60°) |
| Surface tension | LB-ADSA estimate from a sessile drop | Pendant drop, up to 75 mN/m |
| Surface free energy | Calculate yourself from several liquids | Equation of State, Fowkes and van Oss Chaudhury Good in the app; OWRK in our free calculator |
| Dosing | Your own syringe | Manual Hamilton syringe; optional auto dropper, US$2,000 |
| Platform | Any computer running ImageJ (EPFL plugins recommend version 1.46) | Included Android phone, or your own iPhone on iOS 15 or later; analysis offline |
| Power and portability | Depends on your rig; usually one bench | 5 V, battery up to 8 h; 1 kg |
| Data export | ImageJ results table | TIFF images, CSV results |
| Audit trail and electronic signatures | No | No |
| Support and warranty | Community forums | 5 year warranty (phone and syringe excluded), 5 years of software updates |
Checked 23 October 2026. ImageJ plugin details come from the EPFL Biomedical Imaging Group pages, imagej.net and the papers in the references. Dropometer figures come from the Dropometer specification. A DIY setup has no stated accuracy, so we do not invent one.
How we built this comparison
We read the documentation and papers behind each ImageJ plugin and compared them with the Dropometer's published specification. We did not run a timed side by side study for this page, so it gives no time per sample or repeatability figures for either route.
Disclosure: Droplet Lab makes the Dropometer, so read this page knowing that. Every competitor figure links to the maker's own page or datasheet, and where a figure is not published we say so. The verdict would change for a lab that runs fewer than a few dozen static angles a year and already owns a good camera: there, the free route wins on cost.
Expert perspective
A DIY ImageJ setup usually means placing a drop, taking one photo and reading one number. That is the habit the quote below warns about.
Why a single photo is not enough
"Place a drop and just read it and you get an apparent angle, a value somewhere between advancing and receding that isn't much use. Zisman settled that in the fifties."
What this means for a DIY setup: record a short video while you add and then withdraw liquid, and read the advancing and receding angles frame by frame. The Dropometer measures both in the app.
Recommendations by scenario
A few static angles a year, camera already on hand
Pick: DIY ImageJ. A free plugin and careful technique are enough. See the occasional and lowest budget guide.
Teaching drop shape analysis
Pick: ImageJ for method classes; the US$999 education unit when each group needs a working instrument. See the teaching lab guide.
Routine measurement or several operators
Pick: Dropometer. Automatic edge and baseline detection keeps readings consistent between people. See the industrial QA guide.
Contact angle plus surface tension or surface energy
Pick: Dropometer. One kit covers all three, with a published accuracy figure, inside US$5,000. See the under US$5,000 guide.
Measuring on site or away from a bench
Pick: Dropometer. It runs on battery and analyses offline. See the field and on site guide.
Bottom line
Use ImageJ when budget is the hard limit and the job is a few static angles or a class on drop shape analysis. The plugins are free for research use and described in peer reviewed papers. Choose the Dropometer when the same number has to come out whoever measures, when you also need surface tension or surface energy, or when you measure away from one bench. If you are unsure, book a 15 minute demo and bring a sample you already measure in ImageJ.
Frequently asked questions
Can I measure contact angle in ImageJ for free?
Yes. ImageJ and Fiji are free, the Contact Angle plugin is free, and DropSnake and LB-ADSA are free for research use. You supply a sharp side view image of the drop and mark or confirm the drop profile and baseline; the plugin calculates the angle.
Which ImageJ contact angle plugin should I use?
For a quick static angle on a symmetric drop, the Contact Angle plugin is simplest. DropSnake suits drops that are not symmetric. LB-ADSA fits the Laplace equation and also estimates surface tension, but works best on symmetric drops with a clear profile.
Is ImageJ accurate enough for research?
It can be, with careful technique. The DropSnake paper reports a standard deviation of about 0.2° on synthetic test drops. Real images add error from your camera, lighting, levelling and baseline choice, which no plugin controls, so report your setup with your numbers.
Can ImageJ measure surface tension?
LB-ADSA estimates surface tension from a sessile drop image. For routine surface tension most labs use the pendant drop method, which the Dropometer runs up to 75 mN/m.
What does the Dropometer add over ImageJ?
The camera, backlight, stage and syringe in one kit, automatic edge and baseline detection, dynamic angles, pendant drop surface tension and surface free energy in one app, and a 0.35° accuracy figure validated against a KRÜSS DSA100E. Sliding angle needs the optional tilt stage.
Other instrument comparisons
How the Dropometer compares with other contact angle goniometers and surface screening tools.
Dropometer vs Ossila Contact Angle Goniometer
Entry benchtop, about US$3,000
Dropometer vs KRÜSS DSA100 and DSA25
Premium benchtop, quote only
Dropometer vs DataPhysics OCA series
Premium benchtop, quote only
Dropometer vs Biolin Scientific Attension Theta
Premium optical tensiometer, quote only
Dropometer vs ramé-hart goniometers
Benchtop range with published prices
Dropometer vs Brighton Science Surface Analyst
Handheld water contact angle for production
Dropometer vs dyne pens and test inks
Pass or fail surface energy screening
All contact angle goniometer buying guides
Best instrument by budget and use case
Validated measurement approach
Where the Dropometer's accuracy figure comes from.
Benchmarked against a KRÜSS DSA100E
Dropometer contact angle and pendant drop surface tension were compared with a KRÜSS DSA100E in two peer reviewed papers: Review of Scientific Instruments (2018) and Colloids and Surfaces A (2017).
Used in 52 customer publications
Customers have cited the Dropometer in 52 peer reviewed papers, theses and conference papers, listed with links.
References
1.
Stalder et al. (2010). Low-bond axisymmetric drop shape analysis for surface tension and contact angle measurements of sessile drops. Colloids and Surfaces A 364, 72 to 81
The LB-ADSA method behind the ImageJ plugin.
3.
EPFL Biomedical Imaging Group: Drop shape analysis (DropSnake and LB-ADSA)
Plugin download and documentation, checked 23 October 2026.
4.
imagej.net: Contact Angle plugin (Marco Brugnara)
Sphere and ellipse approximation plugin, checked 23 October 2026.
5.
Huang et al. (2021). OpenDrop: Open-source software for pendant drop tensiometry and contact angle measurements. Journal of Open Source Software 6(58), 2604
Free alternative to ImageJ; source of the camera cost range.
6.
Chen, Muros-Cobos and Amirfazli (2018). Contact angle measurement with a smartphone. Review of Scientific Instruments 89, 035117
Peer reviewed validation of the Dropometer's contact angle method against a KRÜSS DSA100E.
7.
Droplet Lab: Dropometer technical specification
Dropometer price, ranges, accuracy, add-ons and export formats, checked 23 October 2026.