# NOrmalizing Tally to get Flux value

**URL:** <https://openmc.discourse.group/t/normalizing-tally-to-get-flux-value/99>\
**Category:** User Support\
**Created:** [August 24, 2014, 6:46pm UTC](https://openmc.discourse.group/t/normalizing-tally-to-get-flux-value/99 "2014-08-24T18:46:47Z")\
**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 26, 2014, 5:49pm UTC](https://openmc.discourse.group/t/normalizing-tally-to-get-flux-value/99/6 "2014-08-26T17:49:12Z")

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The tally is not normalized by volume, so the units are something like [neutrons-cm/source]. This can be understood quite easily: in a collision estimator tally, OpenMC accumulates 1/Sigma\_t which has units of cm, and similarly for a tracklength tally, OpenMC accumulates the tracklength in cm. When you divide by volume, you get [neutrons/cm^2-source]. The normalization factor P_nu/(Q_k) gives you [J/sec_neutrons/fission/(J/fission_neutrons/source)] = [source/sec] so that when you multiply the flux by the normalization factor, you get [neutrons/cm^2-sec].

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