Turn an STL into a PNG
A picture of your model with nothing behind it. The background is transparent, so it drops onto a white page, a dark slide or a coloured listing without a grey rectangle around it. You frame the shot in the 3D view and the picture is exactly what you see.
Drag a 3D file here, or.
This page is set up for STL files. Other formats we can read work here too.
The file is read on your own computer. It is never uploaded.
Your file is read by your own browser and never sent to a server. There is no upload, no account and no copy of your model anywhere but on your computer.
Transparency is the reason to choose PNG
This is the whole difference between this page and the JPG one. A PNG records, for every pixel, how opaque it is — so the area around the model is genuinely empty rather than white.
Put that on a dark slide and the model sits on the dark. Put it on a coloured product page and it sits on the colour. A JPEG of the same model would bring a white box with it, and cutting that box out afterwards is fiddly work that the format has just saved you.
PNG is also lossless, so the edges of the model stay crisp instead of picking up the soft halo that JPEG compression puts around a hard edge against a flat background. On a render, which is all hard edges against flat backgrounds, that is visible.
The view you leave is the picture you get
The picture is the 3D viewport, exactly as it stands: same angle, same zoom, same pixel size. Drag to rotate, scroll to zoom, and switch off the grid with the button in the corner of the viewport — a grid in a cut-out picture defeats the point of cutting it out.
The image comes out at the size the viewport is on your screen, so widening the browser window before taking it gives a larger picture. There is no resolution box because there is nothing to choose: the render is the viewport.
What it is for
Listings, documentation, slides, README files, thumbnails, and anything where a part has to be shown to somebody who has no CAD software. A three-quarter view reads better than a straight-on one because it shows depth.
It is not for anything anybody needs to measure or print. The picture holds no dimensions and no geometry, and no tool can recover them from it — the shape was never recorded. Send the STL for that; it is usually the smaller file.
What survives, and what does not
Kept in the PNG file
- Exactly the view you framed, at the size of the 3D viewport
- A transparent background, so the model drops onto anything
- Crisp edges, because PNG is lossless
Lost on the way
- All three dimensions — a picture is flat, and there is no way back
- Any scale or measurement
How to convert STL to PNG
Drop the .stl file in
The model appears in the 3D view.
Switch the grid off
The button is in the corner of the viewport. A grid behind a cut-out model is the one thing that spoils the effect.
Turn the model to the angle you want
Drag to rotate, scroll to zoom. Three-quarters from slightly above usually shows a part best.
Widen the browser window if you want a larger picture
The image is taken at the size of the 3D view on screen.
Press the button and save the PNG
Open it on a coloured background to check the transparency is doing what you want.
STL and PNG compared
| Property | STL.stl | PNG.png |
|---|---|---|
| File contents | Binary or plain text. Binary is an 80-byte header, a triangle count, then 50 bytes per triangle. | Binary, losslessly compressed with DEFLATE, in labelled chunks. |
| Geometry | Triangles only. Curves are approximated when the file is made, and cannot be recovered. | None. It is a grid of pixels. |
| Units | None. The file stores bare numbers, and every reader has to guess what they mean. | Optional pixels-per-metre in a pHYs chunk, usually absent. |
| Colour and texture | None. There is no place in the format for a colour, a material or a texture. | Up to 16 bits per channel, with full alpha transparency. |
| Separate objects | One body. Several parts written into one STL become one undivided lump of triangles. | One image. |
| Published by | 3D Systems, 1987, for the first stereolithography machines. | The PNG Development Group, 1996, to replace GIF. Now ISO 15948. |
| Written by | Every CAD program and every slicer, as the common denominator. | Every image editor, every screenshot tool, every browser. |
Questions
- Is the background really transparent?
- Yes. The render is taken with nothing behind the model and the transparency is written into the PNG. Viewers that cannot show transparency will usually put white or a checkerboard behind it, which is their choice rather than part of the file.
- How do I get a bigger image?
- Make the browser window wider before you take it. The picture is the 3D viewport at its screen size, so the viewport is the resolution control.
- Should I use PNG or JPG?
- PNG when the picture is going on top of something — a slide, a coloured page, a listing with a background. JPG when it is going somewhere white anyway and you want a smaller file.
- Can a PNG be turned back into a model?
- Not into a model of the object. A picture records brightness rather than distance. Brightness can be treated as height, which gives a relief — the image to STL tool does that, and it is right for a plaque and wrong for recovering a part.
Where to go next
The other direction
Other things to do with a STL file
Other ways to get a PNG file
Related guides and tools
- Gridfinity generatorBins and baseplates, any size, built in the browser
- Turn text into an STLType a word and print it, without drawing anything
- Turn an image into an STLA photo or a logo, turned into something you can print
- Lithophane generatorA photo printed as thickness, lit from behind
- Repair an STL that will not sliceClose the holes and separate the bad edges so a slicer accepts it
- STL to G-codeGuide
- How to convert an STL file to G-codeGuide