Charged jet cross sections are mesured with jet cone radii R=0.2 and R=0.4 in our analysis. To extract these cross sections, LHC15n lowIR data is used.  We also estimated charged jet cross section ratio of R=0.2 to R=0.4. The ratio is well described by PYTHIA6 (Perugia-2011) and PYTHIA8 (Monash-2013). We saw certain discrepancy with POWHEG production but please note thet there is a difference on the Underlying event(UE) treatment. UE is not subtracted for our result. On the other hand, UE is subtructed for POWHEG result. It may describe the discrepancy because the UE subtraction should increase the ratio value.