"Can I trust these cost-of-living calculators?" I wouldn't. As people have already mentioned, taxes and housing will likely be your largest increased expenses

"Can I trust these cost-of-living calculators?" I wouldn't. As people have already mentioned, taxes and housing will likely be your largest increased expenses when compared to an area like Boca Raton. I would go onto some home-search sites and start looking around at actual places for rent. You'll quickly get an idea of exactly what you would be paying if you moved out today. To give you a general idea, lots of very non-posh 3 bedroom, 2 bath single family homes in Santa Clara go for $3-5k/month. However, that number can differ wildly by moving even a few blocks in any direction. Feel free to email me if you want to discuss specific areas further.