# Volume calculation and flux tally units

**URL:** <https://openmc.discourse.group/t/volume-calculation-and-flux-tally-units/235>\
**Category:** User Support\
**Created:** [August 18, 2016, 10:18am UTC](https://openmc.discourse.group/t/volume-calculation-and-flux-tally-units/235 "2016-08-18T10:18:21Z")\
**Posts on this page:** 1\
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**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\
**Post date:** [August 19, 2016, 3:53pm UTC](https://openmc.discourse.group/t/volume-calculation-and-flux-tally-units/235/4 "2016-08-19T15:53:24Z")

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The volume of a 2D mesh cell in a 3D geometry is the 2D area times the length of the geometry in the third dimension (i.e., wherever there could be a flux of neutrons). So, your calculation of (5/100) \* (5/100) \* 5 seems to be correct.

Best,  
Paul

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