Free Online Stereonet Plotter
Paste strikes and dips from your field notebook and get an equal-area or equal-angle stereonet with great circles, poles and density contours — free, in the browser, with nothing uploaded.
What a stereonet shows
A stereonet is a two-dimensional projection of the lower hemisphere of a sphere, and it exists to solve one problem: orientations in three dimensions are hard to compare in a list. A plane becomes a great circle, or more compactly a single point — its pole, the normal to the plane. A lineation becomes a point. Once everything is a point, patterns that were invisible in a spreadsheet become obvious.
Two projections are in common use and they are not interchangeable. The equal-area (Schmidt) net preserves area, so the density of points is a true density — it is the only correct choice if you intend to contour your data or talk about a preferred orientation. The equal-angle (Wulff) net preserves angles, which makes it the traditional choice for angular constructions and crystallographic work.
Data
Paste straight from Excel or Google Sheets — include the header row and the columns are matched by name, in any order.
| # | Type(opt) | Strike (RHR)° | Dip° | Trend°(opt) | Plunge°(opt) | Set(opt) | Label(opt) | |
|---|---|---|---|---|---|---|---|---|
| 1 | ||||||||
| 2 | ||||||||
| 3 | ||||||||
| 4 |
0 rows of data
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Who uses one
Structural geologists mapping foliations, bedding and fold geometry. Engineering geologists and mining geotechnicians running kinematic analyses of rock slopes, where planar sliding, wedge failure and toppling each produce a recognisable arrangement of poles relative to the slope face and the friction cone. Also mineral exploration teams correlating vein orientations, and anyone with a borehole televiewer dataset.
How to read it
North is at the top and azimuths run clockwise. Strike is measured with the right-hand rule, dip from 0° (horizontal) to 90° (vertical). A shallowly dipping plane plots as a great circle hugging the outer primitive circle; a steep plane plots as a great circle passing close to the centre. A vertical plane is a straight line through the centre.
Poles are usually the more useful view. A tight cluster of poles means one consistent set of planes, and the mean pole gives you the mean orientation. Poles spread along a girdle mean the planes have been folded — and the pole to that girdle is the fold axis, the π-axis construction. Two or three distinct clusters mean two or three joint sets, which is exactly what a rock-mass characterisation needs.
Common questions
- Equal-area or equal-angle — which should I use?
- Equal-area (Schmidt) for anything statistical: density contouring, mean orientations, comparing how tight two clusters are. Equal-angle (Wulff) if you are doing angular constructions or matching a published crystallographic figure.
- Do you accept dip direction instead of strike?
- Yes. Dip direction is simply strike plus 90° under the right-hand rule, and the plotter accepts either convention.
- I take readings on my phone in the field. How do I get them onto my laptop?
- With “Send to device”, and without a cloud folder in between. Type or paste the readings on whichever device is with you, and you get a QR code and a plain link; scan the code with the other device and the whole table opens there, ready to plot. The orientations travel inside the link itself — in the part after the “#”, which browsers never transmit to any server — so nothing is uploaded at either end. Making a link is a Pro feature; opening one is free for whoever you send it to. Around forty readings fit comfortably in a scannable code, and past that the link still works.