How to measure a 3D model in STL Viewer
Tap two points on a 3D model to get the distance and the X, Y and Z differences in mm or inches. Premium tool, with one free try after a short ad.
Measure gives you the exact distance between any two points on a model: the gap between two holes, the thickness of a wall or the length of an edge. It is a Premium tool, and you can try it once for free by watching a short ad.
Measure between two points
- Open the model and tap Measure in the tools.
- When the hint says Tap a point on the model, tap the first point on the surface.
- When it says Tap a second point, tap the second one. If you tap empty space, the app asks you to tap on the model.
- Read the Distance and the differences along each axis: ΔX, ΔY and ΔZ.
- Tap Clear to start a new measurement, or close the tool when you are done.
Reading the result
- Distance is the straight line between the two points, through the air, not along the surface.
- ΔX, ΔY, ΔZ split that line along the axes. To measure a height, for example, tap a point on the top and one on the bottom and read ΔZ, even if the points aren't exactly above each other.
- Values are shown in your display unit, millimeters or inches, which you set under Units in Settings.
Zoom in and rotate before you tap, so the point lands exactly on the edge or face you want. Turn on Axes in the toolbar to see which direction is X, Y and Z (see view modes).
Check the units first
Measurements are only right if the model's unit is right. STL, OBJ and PLY files don't store one, so millimeters are assumed. If a part that should be 2 inches long measures about 2 mm, switch the File units to inches in Model info.
Very large models
When a huge mesh is shown as a simplified view, the result is marked as approximate, because you tapped on the lighter version of the model. For most checks it is close enough; for tight tolerances, measure in your CAD software.
Premium and the free measurement
Measure is part of Premium, a one-time purchase or a yearly subscription that also unlocks Section, Scale & export and Compare and removes ads. Without Premium, tapping Measure offers Watch an ad: after a short ad you can take one measurement. When that is used, See Premium shows the options. If no ad is available, try again later.
For a whole-model resize based on a measured part, see Scale & export. Our blog explains how to measure and scale an STL in more depth.
Learn more on the blog
- Scale STL to an Exact Size and Measure It (Worked Example)
- Check Your STL Before Printing: An 8-Point Checklist
Questions and answers
Can I measure without Premium?
Yes, once. Tap Measure and choose Watch an ad: after a short ad you can take one measurement. Premium lets you measure as often as you like.
Is the distance measured along the surface?
No. Distance is the straight line between the two points. ΔX, ΔY and ΔZ show that line split along each axis.
Why does the result say approximate?
The model is very large and shown as a simplified view, so the points were picked on the lighter version of the mesh.
More guides
- How to open STL, OBJ, 3MF and PLY files on Android
- How to use view modes and gestures in STL Viewer
- How to check a 3D model's size and volume
- How to estimate filament for a 3D print
- How to see inside a 3D model with Section
- How to scale a 3D model and export it as STL
- How to compare two 3D models side by side
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Free STL, OBJ, 3MF and PLY viewer for Android. Works offline.