Detect and fix surface orientation issues. One-click recalculate or flip, eliminate black faces for accurate preview and printing.
or click to browse, paste supported
This tool is designed to fix surface orientation issues in 3D models. If black areas appear in the preview or some faces display abnormally, it is usually caused by incorrect surface orientation. Simply upload the model, and the tool automatically detects abnormal orientation and offers two repair methods: recalculate or flip all. After repair, the model renders correctly and is suitable for 3D printing, gaming, AR, and more. Supports STL, OBJ, GLB, and other formats. Normals are recalculated locally in the browser; files are not uploaded to any server.
About this tool
Black faces are usually caused by inconsistent surface orientation, where some faces point inward instead of outward. This tool can automatically detect and fix them, making all surfaces face the correct direction.
No. The repair only adjusts surface orientation, without changing the model's geometry, size, or details. The output remains identical to the original model.
After repair, the model's surface orientation is correct. It will no longer show black faces during preview and slicing in 3D printing software, resulting in better print quality.
Yes. The tool processes all parts of the entire model, automatically detecting and fixing the surface orientation of each part without requiring manual splitting.
Recalculate rebuilds vertex normals from current face directions; use it when normals are missing or corrupted but faces still point outward. Flip All reverses the winding of every triangle; use it when the whole model is inside out. Try Recalculate first; if black areas persist, apply Flip All.
No. After repair every face points outward, so single-sided rendering works correctly in viewers and slicers. Any double-sided material setting from the source file is preserved when exporting.
General questions
Yes, Any3D's core features are free to use forever. We provide format conversion, model optimization, and online preview at no cost, with no registration required.
No. Files you select are processed only in your browser on this device, so they never leave your device and are never sent to our servers. We don't store any user files; after processing, related data in browser memory is released.
No installation required. Any3D is entirely browser-based; just open the webpage to use all features. It works on Windows, Mac, Linux, and other major operating systems.
There is no cap on file size or polygon count. How large a model you can open depends on your device's memory and graphics card, and very heavy models may make the page lag or crash. Some tools do limit how many files go in at once, such as 50 models per batch or single images up to 50 MB in texture compression. See Limits for the full list.
