calculating total yield for Illumina sequencing run

Question

[genya35]

Hello, I'm trying to calculate ChipResultsSummary 'yield' for Hiseq sequencing run, that is listed in BustardSummary.xml file manually, so I can avoid parsing the file. I've tried yield_g from InterOp, however, the numbers are getting are ~3% lower than expected. Could someone suggest how to calculate this number correctly.

Thanks you