Upload a JPG, PNG, SVG or HEIC, set the threshold and height, and download an STL your slicer can open on any desktop or phone.
Convert an image to STLAn image to STL converter online does one job: it reads the pixels of a picture and writes a triangle mesh you can slice and print. No account, no installer, no command line. You upload a file, the browser builds the surface, and you download an STL. The run happens in the tab. That matters when the file is a client logo, a signature, or a photo of a part you are trying to reproduce.
People land here for three reasons. A designer has a flat logo, silhouette or line drawing and wants a keyring, a coaster or a stamp. A tinkerer has photographed an old bracket and needs a printable replacement, even if the geometry is only approximate. A teacher or hobbyist has a map outline, a stencil or a shape from a datasheet and wants it as plastic. All three want the same thing: a mesh with real proportions, generated without installing CAD they do not own or do not have the rights to install.
The conversion is a short pipeline, and each stage is worth understanding before you upload.
The converter looks at brightness, not colour. Every pixel is sorted into foreground or background against a threshold you control, then the boundary between the two is walked and closed into one or more paths. Invert the decision if your subject is light on a dark background.
Each closed path is given a physical width and extruded to the height you set in millimetres. Curves and diagonals are broken into straight segments, which is why a resolution setting exists at all. Internal loops become holes; separate loops become separate islands inside the same mesh.
STL describes only the outer surface: a list of triangles, each with three vertices and a normal. No colour, no texture and no unit label are stored in the file. Your slicer decides what the numbers mean, and most assume millimetres.
A print that fits first time comes from decisions made before the upload and checks made after it.
Line art, logos, silhouettes and stencils convert cleanly; mid-tone photographs do not, because there is no unambiguous edge. Working at 1000 pixels or more on the long edge keeps curves smooth. JPG, PNG, GIF, BMP, TIFF, WebP, SVG and HEIC are all accepted, up to 20MB.
Move the cutoff until the preview shows a solid shape with the detail you want and no floating specks. Invert it if your subject is lighter than the background. Remove stray islands now, because every one becomes a separate solid you have to delete later in the slicer.
Type the real width in millimetres and the height you want the relief to rise. A 2 mm relief reads well on a coaster, while a 20 mm extrusion is a stand-alone object. Keep the aspect ratio locked unless you deliberately want the shape stretched.
More triangles smooth the curves and inflate the file; fewer triangles print just as well and slice faster. A 0.4 mm nozzle cannot reproduce detail finer than about 0.4 mm, so resolution beyond that is wasted. Walls thinner than roughly 0.8 mm will not survive a single perimeter.
STL carries no units, so check the imported size before you slice. Look at the preview for non-manifold edges, inverted normals and shells that float in mid-air. Fix or re-export before you spend filament.
The first limit is bandwidth, not processing power. Uploads are capped at 20MB, and a 20MB TIFF pulled over hotel wifi or phone data takes real time to arrive. On a locked-down work laptop the browser is often the only tool you are allowed to run, which is exactly why doing the work there helps: the same URL gives the same result on Windows, macOS, Linux, iOS and Android. Treat a flaky connection as the main variable, and resize oversized photos first.
The second limit is geometry. A single photograph carries no depth information, so what you get is a 2.5D result: a silhouette or tonal relief extruded to the height you set, not a scan of the object. Colour and texture live in the image file, not the STL, and nothing downstream can recover them. Holes appear only where the trace finds a genuinely closed loop. A photo of a bracket with a hard shadow on one side will trace the shadow too.
The third limit is what the printer can hold. Features thinner than your nozzle diameter, usually 0.4 mm, simply will not come out, and sharp internal corners round off. Big flat plates are fine but consume triangles for nothing. Because STL is unitless, the same file can read as 20 mm across in one slicer and 20 inches in another if the import setting differs. Check the bounding box after import.
This is the converter described above: upload your file, set the threshold, size and height, then download the STL. It runs in the tab, so the result is identical whatever device you are holding.
No. The converter runs in the browser tab, so there is nothing to download and no sign-in for a basic conversion. That is the point of the online route: it behaves the same on a managed work laptop, a Chromebook, a Linux desktop, an iPhone or an Android tablet.
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