FREE TO USE · YOUR FILE STAYS ON YOUR DEVICE
STL Model Size Checker
Use the model size checker to measure STL bounds, calculate a target scale and download a dimension report. Files stay in your browser.
Drop your STL here
ASCII or binary STL · maximum 25 MB · up to 400,000 triangles
Your model stays on your device. No account needed.Use the model size checker in three steps
- Select an STL and its export unit. The model size checker accepts ASCII or binary STL, up to 25 MB and 400,000 triangles. Millimeters are an assumption, not detected metadata.
- Choose the calculation. Enter a scale percentage, or select one target axis and a desired length in millimeters. Calculate uniform scale to preserve proportions.
- Keep the result. Download the text report. Apply the percentage in your editor or slicer, export again and measure the resulting file.
Dimensions for a specific delivery
This model size checker measures the outer bounds along the file’s X, Y and Z axes. It is useful for a print envelope, a supplier’s requested overall size or a model exported under the wrong unit convention.
The model size checker does not measure a hole diameter, wall thickness or distance between selected points. Camera rotation does not change the bounds. A rotated export can have different extents because its geometry uses different axes.
Only need to inspect the surface? Open the STL viewer →Worked example: turn a 20 mm edge into 50 mm
Load Try a sample model in the model size checker. With millimeters selected, the original bounds are 20 × 30 × 40 mm. Choose target axis X and enter 50 mm. The calculation is 50 ÷ 20 × 100 = 250%, giving 50 × 75 × 100 mm.
The model size checker applies one factor to all three axes. Entering 50 mm for X does not make every edge 50 mm. A cube would require changing the shape’s proportions, which this tool does not do. The target calculation starts from the original coordinates, so it does not compound a previous percentage.
| Sample setting | Scale | Calculated X × Y × Z |
|---|---|---|
| Millimeters, original size | 100% | 20 × 30 × 40 mm |
| Millimeters, half size | 50% | 10 × 15 × 20 mm |
| Millimeters, target X = 50 | 250% | 50 × 75 × 100 mm |
| Centimeters, target X = 50 | 25% | 50 × 75 × 100 mm |
These model size checker results are reproducible with the supplied box; they are calculations, not measured physical prints. Try a second shape with the 60 × 40 × 3 mm outline exercise and compare each axis after export.
Separate a unit mismatch from a scale decision
STL coordinates do not reliably declare physical units. The model size checker interprets one coordinate unit as 1 mm, 10 mm or 25.4 mm when you select millimeters, centimeters or inches. Choose the convention used by the exporter before changing the size.
For example, a one-inch edge stored as a coordinate length of 1 appears as 1 mm under the default assumption. Selecting inches makes it 25.4 mm at 100%. The model size checker has changed the interpretation, not discovered the designer’s intent; confirm it against the source project or a known dimension.
If the original physical size is correct but the project needs a smaller object, keep the unit and change scale. If every edge is wrong by the same factor of 10 or 25.4, inspect the unit convention first. Scaling to hide a unit error can complicate later revisions.
Check build space without losing fitted features
Compare all three model size checker outputs with usable build space, not just the printer’s advertised width. Allow room for a brim, supports and excluded areas. A 180 mm-wide model may not fit comfortably on a nominal 180 mm bed.
Uniform scaling also changes wall thickness, peg diameters and clearances. The model size checker cannot tell whether a scaled joint will still fit. For a large assembly whose fitted features must remain unchanged, consider cutting the model into parts rather than shrinking the entire object.
Questions about measurements and reports
Does the model size checker resize my STL?
No. The model size checker calculates dimensions without modifying vertices or exporting geometry. Apply the reported percentage to the original model in a compatible editor or slicer. Reopening the new export is the way to verify that the change was applied.
What is in the downloaded report?
The model size checker report records the filename, selected input unit, original millimeter bounds, uniform percentage and calculated bounds. It is a local text download, not a manufacturing certificate. Keep it with the original export so another person can reproduce the assumptions.
Why is a target length rejected?
The model size checker requires a positive finite length and a resulting scale no greater than 10,000%. A zero-length axis cannot define a scale factor. Choose another axis for a flat mesh, and check the units before requesting an extreme enlargement.
Can I measure OBJ, GLB or an internal gap?
This model size checker supports STL outer bounds only. Use the authoring application for selected-point or internal-feature measurements. The format guide explains what changes when a scene is exported as an STL surface.
Is the model processed privately?
The model size checker processes geometry in your browser and creates the report locally. Website loading still makes ordinary host requests. Clear the model when finished and consult the privacy policy for memory and hosting limitations.