Is my STL file uploaded anywhere?

No. The file is read and rendered entirely by your own browser. It is never sent to a server, which is also why there is no file-size limit.

How large a file can I open?

There is no file-size cap in the page. Available memory and the graphics chip set the practical ceiling. Reading and starting the drawing have a 30-second deadline; if they take longer, export a simpler mesh and try again.

Does it handle both binary and ASCII STL?

Yes. Both formats open, including binary headers beginning with solid, ASCII with a UTF-8 byte order mark, and multiple complete ASCII solids. The whole file is checked: incomplete facets, extra vertex fields, nonfinite values and unaccounted binary bytes are refused.

What do the dimensions mean?

They are the model’s axis-aligned bounding-box size along the source X, Y and Z axes, in that order. STL carries no unit information: interpret them using the export unit. Ordinary lengths use two decimals from 1 up and four significant figures below 1; extremely small or large lengths use scientific notation. The complete summary includes unrounded bounds and dimensions.

Do I need to install anything or sign up?

Neither. It runs on the page, with no account and no download.

Why are the dimensions far bigger or smaller than I expected?

STL stores bare numbers without a unit label. A part exported in millimeters, inches or meters keeps those numbers here. Measurement uses the original binary Float32 coordinates or complete ASCII coordinates parsed as finite Float64 numbers. Drawing is centered and uniformly normalized separately, so it can show very large, tiny or off-origin models without changing the reported source bounds.

How do I turn, zoom and reset the model?

Drag to turn it, scroll or pinch to zoom, and drag with the right mouse button or two fingers to move it. With the view focused, the arrow keys turn it by 15 degrees (45 with Shift), plus and minus zoom, and 0 puts the view back where it opened; Reset view does the same with a click. Wireframe shows the triangles themselves, and the choice is remembered in this browser.

Can I measure an STL model’s dimensions online?

Open the STL and read its overall X, Y and Z dimensions. These are the model’s axis-aligned bounding-box dimensions, not a point-to-point caliper measurement. STL stores coordinates without a unit label, so interpret the numbers using the unit used when the model was exported, commonly millimeters for a 3D print.

Does the viewer calculate volume or check whether a part is printable?

No. It provides viewing, a triangle count and overall bounding dimensions. It does not measure point-to-point distances, calculate volume, repair a mesh or certify watertightness or printability. Zero-area triangles remain counted and may be invisible. Colours and other nongeometry attributes are not displayed.

Are recent files stored in this browser?

Only recent file names and the wireframe preference are saved locally after deliberate use. The files and their geometry are not stored. Use Forget recent names and preference to remove those saved settings. Hiding the page clears the model and cancels pending reading.

STL Viewer

Open any STL file straight in your browser. Rotate it, inspect the mesh, and read its real dimensions and triangle count. Your file never leaves your computer, so there is no upload wait and no size limit.

Open an STL file

Choose a file, drop or paste one, or

No size limitNo accountNothing uploadedLocal file processing

Common questions

Is my STL file uploaded anywhere?: No. The file is read and rendered entirely by your own browser. It is never sent to a server, which is also why there is no file-size limit.
How large a file can I open?: There is no file-size cap in the page. Available memory and the graphics chip set the practical ceiling. Reading and starting the drawing have a 30-second deadline; if they take longer, export a simpler mesh and try again.
Does it handle both binary and ASCII STL?: Yes. Both formats open, including binary headers beginning with solid, ASCII with a UTF-8 byte order mark, and multiple complete ASCII solids. The whole file is checked: incomplete facets, extra vertex fields, nonfinite values and unaccounted binary bytes are refused.
What do the dimensions mean?: They are the model’s axis-aligned bounding-box size along the source X, Y and Z axes, in that order. STL carries no unit information: interpret them using the export unit. Ordinary lengths use two decimals from 1 up and four significant figures below 1; extremely small or large lengths use scientific notation. The complete summary includes unrounded bounds and dimensions.
Do I need to install anything or sign up?: Neither. It runs on the page, with no account and no download.
Why are the dimensions far bigger or smaller than I expected?: STL stores bare numbers without a unit label. A part exported in millimeters, inches or meters keeps those numbers here. Measurement uses the original binary Float32 coordinates or complete ASCII coordinates parsed as finite Float64 numbers. Drawing is centered and uniformly normalized separately, so it can show very large, tiny or off-origin models without changing the reported source bounds.
How do I turn, zoom and reset the model?: Drag to turn it, scroll or pinch to zoom, and drag with the right mouse button or two fingers to move it. With the view focused, the arrow keys turn it by 15 degrees (45 with Shift), plus and minus zoom, and 0 puts the view back where it opened; Reset view does the same with a click. Wireframe shows the triangles themselves, and the choice is remembered in this browser.
Can I measure an STL model’s dimensions online?: Open the STL and read its overall X, Y and Z dimensions. These are the model’s axis-aligned bounding-box dimensions, not a point-to-point caliper measurement. STL stores coordinates without a unit label, so interpret the numbers using the unit used when the model was exported, commonly millimeters for a 3D print.
Does the viewer calculate volume or check whether a part is printable?: No. It provides viewing, a triangle count and overall bounding dimensions. It does not measure point-to-point distances, calculate volume, repair a mesh or certify watertightness or printability. Zero-area triangles remain counted and may be invisible. Colours and other nongeometry attributes are not displayed.
Are recent files stored in this browser?: Only recent file names and the wireframe preference are saved locally after deliberate use. The files and their geometry are not stored. Use Forget recent names and preference to remove those saved settings. Hiding the page clears the model and cancels pending reading.

Bounds use source binary Float32 coordinates or finite Float64 numbers parsed from complete ASCII STL. Drawing is centered, uniformly normalized and rounded to Float32; tiny relative details can disappear. Overall dimensions and triangle count do not certify mesh quality or printability.