How to calculate worker hashrate at stratum

[startsts]

I use node-stratum-pool and it works well but I cannot calculate hashrate of the worker.
on worker's share this stratum gives me 2 diffs: stratum worker difficulty  and  actual difficulty of the share, what of them I should save to database to hashrate calculations?

[unholycactus]

None of the two you have listed, those are difficulty values and are unrelated to the hashrate.
Your hashrate should be visible from the pool's side, you'll get the most accurate value from them.
Otherwise, it depends on your miner.

[startsts]

None of the two you have listed, those are difficulty values and are unrelated to the hashrate.
Your hashrate should be visible from the pool's side, you'll get the most accurate value from them.
Otherwise, it depends on your miner.

actually MPOS (pool engine) calculates hashrate using stratum worker difficulty,  MPOS shows hashrate for last 5 minutes without normalization, so at pool dashboard hashrate always jumps up and down.   I try the same way but I do hashrate normalization (I calculate average at 60 minutes) and hashrate is 15% lower than my miner program shows,  is ok to lose 15% of hashrate on mining?