# 3D printing file formats compared: STL, OBJ, 3MF and STEP

> Which 3D file format to upload and what STL, OBJ, 3MF and STEP mean for colour, scale and accuracy.

Canonical: https://printimir.ch/en/guides/3d-printing-file-formats-compared

## 3D printing file formats compared: STL, OBJ, 3MF and STEP

Printimir accepts STL, OBJ, 3MF, STEP and STP. The best format depends on where your model comes from.

### STL

The most common format. It describes the surface as a triangular mesh without units or colour. This is entirely sufficient for a single-colour part. Export at a fine enough resolution to keep curves smooth, and use millimetres.

### OBJ

Similar to STL, with optional colour and texture information. We use its geometry for FDM printing. Upload associated files together if your OBJ refers to a material file.

### 3MF

A modern format that stores geometry, units, colours and several parts in one file. If your software exports 3MF, it is often the cleanest choice, especially for multi-colour models.

### STEP and STP

The exchange format used by CAD applications. It describes exact surfaces and edges instead of a triangular mesh, so there is no resolution loss. You do not need to convert STEP to STL; upload it directly. It is ideal for technical parts with exact dimensions.

### Recommendation

- From a CAD application: STEP
- Multi-colour model: 3MF
- Single-colour model from a download source: STL
- Where possible, upload one closed solid per required part

### Frequently asked questions

#### Do I need to convert STEP to STL first?

No. Upload the STEP file directly; it is prepared during the upload process.

#### How large can the file be?

Up to 500 MB.

#### Why is my model shown at the wrong size?

It was usually exported in a unit other than millimetres. You can correct it with scaling in the configurator.

### Read next

[Print a STEP file](https://printimir.ch/en/print-step-file) · [Print an STL file](https://printimir.ch/en/print-stl-file) · [Print a 3D model online](https://printimir.ch/en/print-3d-model-online) · [All guides](https://printimir.ch/en/guides)

### Ready?

Upload your model and see the price instantly, or describe your project if you do not have a file yet.

[Upload model](https://printimir.ch/en/3d-printing/upload-model) · [Request a project](https://printimir.ch/en/3d-modeling/request)