# How to reduce frames of trajectory file?

**URL:** <https://gromacs.bioexcel.eu/t/how-to-reduce-frames-of-trajectory-file/980>\
**Category:** User discussions\
**Created:** [October 19, 2020, 1:18pm UTC](https://gromacs.bioexcel.eu/t/how-to-reduce-frames-of-trajectory-file/980 "2020-10-19T13:18:36Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![mj.rezayani](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/mj.rezayani/32/3918_2.png) [@mj.rezayani](https://gromacs.bioexcel.eu/u/mj.rezayani)\
**Post date:** [October 19, 2020, 1:18pm UTC](https://gromacs.bioexcel.eu/t/how-to-reduce-frames-of-trajectory-file/980/1 "2020-10-19T13:18:36Z")

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GROMACS version:  
GROMACS modification: Yes/No  
Dear all

I want to decrease trajectory frames of my xtc file. All simulation run is 30 ns and I want to get trajectory every 30 ps . I know I have to use trajconv command but I don’t know what kind of options I have to use.

Thank you

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<div class="post-metadata">

**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [October 19, 2020, 1:49pm UTC](https://gromacs.bioexcel.eu/t/how-to-reduce-frames-of-trajectory-file/980/2 "2020-10-19T13:49:36Z")

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`gmx trjconv -skip`

```
-skip (1)
           Only write every nr-th frame
```

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<div class="post-metadata">

**Author:** ![mj.rezayani](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/mj.rezayani/32/3918_2.png) [@mj.rezayani](https://gromacs.bioexcel.eu/u/mj.rezayani)\
**Post date:** [October 19, 2020, 7:19pm UTC](https://gromacs.bioexcel.eu/t/how-to-reduce-frames-of-trajectory-file/980/3 "2020-10-19T19:19:19Z")

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Thank you very much