By law. H1b requires the wages to be greater than the prevailing wage for similar positions in the region. They are published by DoL: https://flag.dol.gov/wage-data/wage-search

For this kind of experience, you'd be looking for level 2 _minimum_ and likely level 3. For King County in WA it's right now $149240 and $180710 respectively. Level 4 wage is $212202, btw.