Measure STL Dimensions Online
Drop an STL, 3MF, OBJ, PLY or GLB file to see its size (W x D x H) in mm, cm and inches, its volume and surface area, and whether the mesh is closed. Click two points on the model to measure the distance between them. The file stays on your device.
How to measure an STL file
- 1
Open the file
Drop an STL, 3MF, OBJ, PLY or GLB file (up to 100 MB) on the box, or try the sample bracket.
- 2
Read the size
Width, depth and height show in mm, cm and inches, with volume, surface area and the triangle count. Copy them with one tap.
- 3
Measure a distance
Click two points on the model. The tool shows the straight distance and the X, Y and Z parts. Snap to corners helps you hit edges exactly.
- 4
Check the fit
Pick your printer (or type its build size) to see if the model fits on the bed, and scale it if it does not.
What the STL measuring tool shows
Everything is read straight from the triangles in your file.
| Dimensions | Width (X), depth (Y) and height (Z) of the bounding box, in mm, cm and inches. |
|---|---|
| Units | STL files store plain numbers with no unit. Slicers read them as millimetres, so this tool does too. If the file was made in inches, centimetres or metres, pick that unit and every number is converted. |
| Volume | The space inside the surface in cm³. It is exact for a closed mesh and an estimate when the mesh has holes. |
| Surface area | The total area of all triangles in cm². |
| Watertight check | Counts open and non-manifold edges, the same check the STL repair tool uses. |
| Point to point | Two clicks give the straight distance plus dX, dY and dZ. With Snap to corners on, each click jumps to the nearest corner of the triangle you hit. |
| Printer fit | Compares the size with common build volumes or your own numbers, and tries the model turned 90 degrees on the bed too. |
| Privacy | The file is read and measured on your device. It is never uploaded. |
Why an STL can come out the wrong size
An STL file has no unit field, only numbers. A part drawn as 2 inches wide is saved as 2, and a slicer reads that as 2 mm, so the print comes out 25.4 times too small. A part saved in metres comes out 1000 times too small.
If the size here looks far too small or far too big, switch the unit until the numbers make sense. Then use the STL scaler to save a copy in millimetres, so every slicer opens it at the right size.
Bounding box vs real size
The dimensions are the size of the smallest box, lined up with X, Y and Z, that holds the whole model. For a part that sits at an angle, the box is bigger than the part itself.
To measure a hole, a wall or the length of an angled edge, click two points instead. The straight distance does not depend on how the model is turned.
Measuring in a slicer or CAD program
Slicers such as PrusaSlicer, Cura, Bambu Studio and OrcaSlicer show the size after you load a model, and some have a measure tool. CAD programs can measure too, after an install and often an account.
This page gives you the numbers in a few seconds on any phone or computer, with no software, which helps when you are checking a file before you buy, print or send it to a print service.
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