# Biphase system

**URL:** <https://gromacs.bioexcel.eu/t/biphase-system/5346>\
**Category:** User discussions\
**Created:** [December 1, 2022, 4:25pm UTC](https://gromacs.bioexcel.eu/t/biphase-system/5346 "2022-12-01T16:25:24Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ramya123](https://avatars.discourse-cdn.com/v4/letter/r/7c8e57/32.png) [@Ramya123](https://gromacs.bioexcel.eu/u/Ramya123)\
**Post date:** [December 1, 2022, 4:25pm UTC](https://gromacs.bioexcel.eu/t/biphase-system/5346/1 "2022-12-01T16:25:24Z")

</div>

GROMACS version: new  
GROMACS modification: No  
Here post your question

How to know how many molecules can be inserted in a cubic box? Is there any third party program to calculate the number of water molecules or polymer molecules needs to be inserted in box.

This question is particularly about building biphase system