Image to STL Converter — Free Online, No Signup
Drop a photo, picture or logo and get a 3D printable STL. Free mode runs 100% in your browser (heightmap relief or silhouette extrude); AI mode generates a full 3D model from a single image.
Photo to STL in Free mode: reliefs, lithophanes and logos
Free mode turns a picture into STL with two geometry tools. Heightmap mode maps brightness to height — bright areas rise, dark areas sink — the classic way to make a photo relief or a lithophane-style panel. Extrude mode thresholds the image into a silhouette and raises it into a solid block, which is exactly what logos, icons and clip-art need.
Everything happens on your device. The image is read into a pixel grid, converted to a closed solid with a flat base, and exported as binary STL — the file never touches a server, and the result drops straight into Bambu Studio, PrusaSlicer or Cura.
Lithophanes are the most popular use: a panel that looks like a plain gray rectangle until you hold it against a light, when the photo appears in shades of thickness. The recipe is heightmap mode with invert on (dark pixels become thick, light pixels thin), a thin base and white filament. Print it vertically with a 0.2 mm layer height and 100% infill, back it with an LED or a window, and an ordinary portrait turns into a striking lamp cover or night light.
Extrude mode follows a different logic — it ignores shading entirely. The image is thresholded into black or white, the chosen regions become a flat-topped solid, and everything else is cut away to the base. That is exactly how you turn a logo, a monogram or clip-art into a printable keychain, stamp, cookie-cutter-style plate or wall sign. Clean edges matter more than resolution here, which is why vector-style graphics and bold silhouettes convert best.
When a picture to STL converter isn't enough: AI mode
A heightmap is a relief — one surface with depth, meant to be viewed from the front. If you need a real, full 3D model you can rotate and print from any angle, that's what AI mode does: upload one image and a generative model reconstructs the whole object, delivered as GLB and convertible to STL right in your browser.
AI generation runs on paid GPU models, so it costs 20 credits per model (new accounts get one free). We won't pretend the two modes are the same: for a photo relief or a logo plate, use Free mode; for a printable 3D version of a product shot, use AI.
Whichever mode you use, the input image decides the result. Resolution matters less than contrast: a sharp 1000-pixel photo with clear light and shadow beats a 12-megapixel shot that is flat and hazy. For heightmap, crop tightly around the subject and raise the contrast before converting; for extrude, remove the background first so the threshold has an easy job; for AI, use one front-lit subject filling most of the frame. A minute spent preparing the image saves ten minutes of tweaking sliders later.
Common image to STL problems and how to fix them
The most common disappointment is a muddy, flat-looking relief. The cause is almost always a low-contrast source: heightmap mode maps brightness to height, so if your photo lives entirely in mid-gray, the relief lives in a narrow height band and shows nothing. Fix it before converting — raise contrast, deepen shadows, or use a photo editor's levels tool — then try again. Pushing the relief strength slider up helps, but it cannot invent shading that was never there.
Extrude mode has its own classic failure: ragged edges and broken islands. A logo saved as a heavily compressed JPEG carries noise around its outline, and the threshold turns that noise into speckles and bridges. Use a PNG or the cleanest source you have, nudge the threshold slider until the silhouette is solid, and add a little smoothing. If tiny details vanish, they were thinner than your nozzle — thicken the source art or enlarge the output size.
Finally, size. A dense heightmap can produce millions of triangles, and while the browser handles it, your slicer may crawl. Two knobs control this: output size (smaller millimeter dimensions mean fewer meaningful triangles for the printer anyway) and smoothing, which collapses fine pixel noise. A lithophane 100 mm wide needs far less mesh density than the raw image suggests — an FDM printer physically cannot reproduce relief finer than its nozzle diameter, so a leaner STL prints identically.
If AI mode's result is close but not right, the fix is usually the input, not the retry: crop tighter, brighten the subject, or pick a photo with a cleaner background before generating again. And remember the AI delivers a GLB first — you can download that file directly for rendering or game use, while the STL conversion happens in your browser at no extra cost.
Image to STL FAQ
Is this image to STL converter really free?
Yes. Free mode (heightmap and extrude) is unlimited, needs no account, adds no watermark, and runs entirely in your browser — we can afford that because your device does the work, not our servers. Only AI mode costs credits: it generates a full 3D model on paid GPU infrastructure, which has a real per-run cost. New accounts get 20 credits free, enough for one AI generation to try it.
What's the difference between Free mode and AI mode?
Free mode creates a 2.5D relief: a surface whose height comes from your image's brightness (heightmap), or an extruded silhouette of your graphic (extrude) — flat-backed, viewed from the front. AI mode reconstructs a complete 3D object with a back, sides and volume, printable from any angle. Rule of thumb: photo reliefs, lithophanes and logo plates → Free; full figurines, products and objects → AI.
Which images convert best?
Heightmap works best with photos that have clear shading and contrast — portraits with directional light, landscapes, textures. Extrude works best with high-contrast graphics on a plain background: logos, icons, silhouettes, clip-art. AI mode prefers a single, well-lit subject that fills the frame against a simple background. In all three cases contrast beats resolution: a crisp 1000-pixel image outperforms a huge, hazy one.
Is my photo uploaded anywhere?
In Free mode, never — the image is decoded and converted on your device and nothing leaves the browser. AI mode does upload the image so the GPU model can process it; it's used only for your generation.
Is the STL file ready for my slicer?
Yes. Both modes export binary STL with proper facet normals and a closed, watertight solid (flat base included), accepted by Bambu Studio, PrusaSlicer, Cura and OrcaSlicer. Set your target size in millimeters before downloading so the STL arrives at print scale — no resizing needed in the slicer. For lithophanes, remember to print the panel vertically for the cleanest result.
How do I turn a photo into a lithophane?
Drop the photo in, choose heightmap mode and enable invert, so dark areas print thick and light areas thin — thickness differences are what form the image when backlit. Keep the base thin, download the STL, and print it in white PLA standing upright with 100% infill. Hold it against a lamp or a window and the photo appears. Portraits and pet photos with soft, directional lighting make the best lithophanes.
Does image resolution matter for the STL?
Less than you'd think. Heightmap mode samples the image into a grid, and beyond roughly 1000–1500 pixels on the long edge, extra resolution only inflates the STL without adding printable detail — your nozzle diameter, typically 0.4 mm, is the real limit. What does matter is contrast and clean separation of light and shadow. A crisp, well-lit 1200-pixel photo will beat a blurry 24-megapixel one every time.