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Resize an STL to an Exact Size

Scale a 3D model to the exact size you need: one dimension in millimetres with the others in proportion, each axis on its own, a percentage, or a unit fix such as inches to millimetres. See if it fits your printer and how much it weighs, then download the STL. Your file never leaves the browser.

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Drop an STL here or click to browse
STL, OBJ, 3MF or PLY · read in your browser, never uploaded
Browser-basedRuns in your browser

This tool processes on your device; your file is not uploaded for processing.

About

A slicer can scale a model, but it is easy to get the number wrong, and the scale is lost the moment you send the file to someone else. This tool writes the size into the file. Drop an STL (or an OBJ, 3MF or PLY), type the height you want in millimetres and the other two dimensions follow in proportion; or untick the lock and set width, depth and height separately for a part that must hit three exact measurements.

The most common sizing problem is not a choice at all: STL files carry no unit, and slicers read every number as millimetres. A model drawn in inches therefore arrives 25.4 times too small, one exported in centimetres 10 times too small and one from a game engine or an AI generator in metres 1000 times too small. When a file opens tiny, the tool offers the unit fix first.

Before you download you see the new size, whether it fits the printer you pick (as it is, or laid on another side), and the solid volume and weight in PLA, PETG, ABS or resin. If it is too big for the bed, the STL Splitter cuts it into parts that fit; for weight with real infill and print cost, the STL Analyzer takes over.

Everything happens in your browser: the file is read, scaled and written back on your device, nothing is uploaded and there is no size limit beyond your computer's memory. The output keeps exactly the same triangles in a binary STL, so nothing is simplified, smoothed or re-meshed. It is free, with no account.

How it works

  1. 1Open Resize an STL to an Exact Size and choose your file or enter the required input.
  2. 2Adjust the settings and preview the result in your browser.
  3. 3Run the tool; the data is processed on your device.
  4. 4Download the output or copy the result when it is ready.

FAQ

›Does resizing change the quality of the model?
No. Every vertex is multiplied by the same factor and the file keeps exactly the same triangles; nothing is simplified or re-meshed. Very small features still need to be printable at the new size.
›Can I set width, depth and height separately?
Yes. Untick “Keep proportions” and type each dimension. The model is stretched non-uniformly, which is fine for plain parts but distorts sculpted or round shapes.
›Why is my STL tiny in the slicer?
STL has no unit field and slicers assume millimetres. A model drawn in inches shows up 25.4 times too small, in centimetres 10 times, in metres 1000 times. Use Fix units to multiply it back.
›Is my file uploaded?
No. It is read and written by your browser; nothing leaves your device.
›How is the weight calculated?
From the model's enclosed volume times the material's density, as a solid part. Real prints use infill and walls; the STL Analyzer computes that weight, the filament cost and the print time.