It's rare to be worth a lot more than $105k in SLC; wages are pretty low and deep specific expertise isn't often bought so much as grown in house. Especially with a startup.
If you're looking at $105k in SLC, you should be asking for $225k+ in SF by my experience.
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We did the calculation between $125k in SF and $45k in SLC a decade ago and SLC came out well ahead for a family of four.
I think SLC salaries vary a lot by technology too. There's a lot of developers I know in that range here that would be around 135 in SF. Completely agreed on how much better of a value it is here though.
If you're looking at $105k in SLC, you should be asking for $225k+ in SF by my experience.
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We did the calculation between $125k in SF and $45k in SLC a decade ago and SLC came out well ahead for a family of four.