# Purpose of .gro file type?

**URL:** <https://gromacs.bioexcel.eu/t/purpose-of-gro-file-type/471>\
**Category:** User discussions\
**Created:** [July 12, 2020, 3:00pm UTC](https://gromacs.bioexcel.eu/t/purpose-of-gro-file-type/471 "2020-07-12T15:00:12Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![darrenphua](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@darrenphua](https://gromacs.bioexcel.eu/u/darrenphua)\
**Post date:** [July 12, 2020, 3:00pm UTC](https://gromacs.bioexcel.eu/t/purpose-of-gro-file-type/471/1 "2020-07-12T15:00:12Z")

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May i know what is the function of having .gro file types as output?  
For example, if i run pdb2gmx i can specify either .pdb or .gro. What is the advantage of choosing .gro if my software can view .pdb files directly as a visual model but not .gro file types?

For subsequent steps such as EM, equil, production, can .pdb be used throughout instead of .gro?

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**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:** [July 13, 2020, 12:37am UTC](https://gromacs.bioexcel.eu/t/purpose-of-gro-file-type/471/2 "2020-07-13T00:37:08Z")

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It’s an old GROMOS file format. Simple and compact. You can use whatever format you prefer.

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<div class="post-metadata">

**Author:** ![darrenphua](https://avatars.discourse-cdn.com/v4/letter/d/bcef8e/32.png) [@darrenphua](https://gromacs.bioexcel.eu/u/darrenphua)\
**Post date:** [July 13, 2020, 1:58am UTC](https://gromacs.bioexcel.eu/t/purpose-of-gro-file-type/471/3 "2020-07-13T01:58:39Z")

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nice! thanks Justin