Check an STL model's width, depth and height before comparing its size in a slicer. Choose a file from your device or use the free bird example. The checker reads your local file in this browser; it does not upload it.
Binary and ASCII STL, up to 160,000 triangles. This calculates dimensions and a preview scale; it does not rewrite your model.
Use the units stated by the model's creator. The checker does not infer them from the coordinates or filename. Width, depth and height follow the file's X, Y and Z axes.
Width x depth x height
Lowest Z coordinate at this scale: . Your slicer can reposition or rotate the model, so check the final placement there.
The projections fit the available space and may sample triangles in larger files. They do not use a shared ruler. Use the numeric dimensions above to compare physical sizes.
Check the scale before printing
- Read the model creator's intended units and dimensions, then choose the actual STL rather than a preview picture.
- Choose millimetres or inches here. Compare the dimensions with the creator's instructions.
- Try a preview percentage or enter a target X width. Apply the same percentage to all axes in your slicer if you want a proportional resize.
- Compare the slicer's final dimensions, orientation and placement. Review its print preview and make a small test before committing to a larger run.
For the built-in example, 100% with millimetres selected gives 30 x 30 x 2.8 mm. Choosing inches for the same coordinates gives 762 x 762 x 71.12 mm. To make its width 25 mm with millimetres selected, use about 83.333% scale.
What this check covers
It measures the minimum and maximum vertex coordinates and shows their difference. It does not repair a mesh, check every STL rule, detect self-intersections, certify a watertight model, calculate supports or predict material strength. A readable file and plausible dimensions do not prove a successful physical print.
The Library of Congress description of binary STL explains its triangle and coordinate structure. An STL projection does not establish that your printer, material or slicer settings are suitable.
Try the free Quiet Wader token
The built-in model is an original AI-assisted raised bird token from GlebNatureStudio. Its digital geometry was checked, but no physical printing or engine testing has been performed. It is a decorative model.
Get the free STL, OBJ and GLB sample with its licence. You can also read the sample licence.
The optional full collection contains eight different bird tokens in STL, OBJ and GLB, with original source code and instructions. The 30 mm models are AI-assisted decorative geometry. They have not been physically print-tested.
See the eight-token collection - $3.95 USDDigital files, not physical prints. Paid studio checkout currently requires a United States billing address. The example and this checker are free; no purchase or account is required.
Common questions
Does the scale control change my STL file?
No. It previews the resulting dimensions. Apply the percentage in your slicer or modelling app and save a separate file there if needed.
Why does the height change after I rotate it in a slicer?
These dimensions follow the file's original X, Y and Z axes. A rotated model can have a different axis-aligned bounding box. Compare the final size in the application that will prepare the print.
Can this confirm that a model is ready to print?
No. It is a size and projection check. A slicer review, geometry validation and physical testing remain separate steps.
GlebNatureStudio. Tool, guide and example geometry created with material AI assistance. Independent resource; no affiliation with a printer or slicer manufacturer.