# vtu or vtk file formats - which is preferred?

**URL:** https://discourse.paraview.org/t/vtu-or-vtk-file-formats-which-is-preferred/6976
**Category:** ParaView Support
**Created:** [April 16, 2021, 12:35pm UTC](https://discourse.paraview.org/t/vtu-or-vtk-file-formats-which-is-preferred/6976 "2021-04-16T12:35:31Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![dculp](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/d/e47c2d/32.png) [@dculp](https://discourse.paraview.org/u/dculp)
#### Post date: [April 16, 2021, 12:35pm UTC](https://discourse.paraview.org/t/vtu-or-vtk-file-formats-which-is-preferred/6976/1 "2021-04-16T12:35:32Z")

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I’m using ccx2paraview v2.3.1 to convert calculix results (static and modal). ccx2paraview can produce both vtu and vtk files. Which of these is preferred by Paraview? Why?

Thanks,  
Don C.

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### Author: ![olesenm](https://discourse.paraview.org/user_avatar/discourse.paraview.org/olesenm/32/17416_2.png) [@olesenm](https://discourse.paraview.org/u/olesenm)
#### Post date: [April 16, 2021, 1:34pm UTC](https://discourse.paraview.org/t/vtu-or-vtk-file-formats-which-is-preferred/6976/2 "2021-04-16T13:34:38Z")

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> [@dculp](#):
>
> I’m using ccx2paraview v2.3.1 to convert calculix results (static and modal). ccx2paraview can produce both vtu and vtk files. Which of these is preferred by Paraview? Why?

The `.vtk` files were marked as a _legacy_ format at least 10-15 years ago. They still see a fair amount of use though, either for historical reasons or that people just find their ASCII format pretty simple to generate and to parse. The xml formats (eg, `.vtu`) should presumably be better streamlined for reading into VTK and provide additional things like compression etc.

If you have the choice of exporting either, then I would definitely take the `.vtp`, `.vtu` (xml) formats. They are also really handy if you want to recombine them in a very lightweight `.vtm` (multiblock) format.  
/mark