Your question is too broad. You're going to get a very big set of answers because you've asked over so much time and space. Please allow me to answer a series o

Your question is too broad. You're going to get a very big set of answers because you've asked over so much time and space. Please allow me to answer a series of more specific questions that may help you understand more than the "average." What are the typical work hours in a large tech company in California? Very few require more than 50 hours a week. Typically people are in office 7-8 hours a day, and often put in some time handling communications or catching up on small sums of work in the evenings. Folks in higher management positions (directors and above) typically work more in a company like this. The demands on directors and above in tech companies are uncharacteristically high. What about medium sized companies with less than 300 people? This starts to get into the "it depends territory." Companies this size are small enough to still become reliant on extraordinary effort from individuals. Being a manager is often very stressful in smaller-but-not-small companies like this because you're always juggling resource scarcity. Engineers should expect 8 hours a day, but occasionally much longer. This kind of company is often not-quite-there-yet on having well-managed infrastructure that doesn't page you at 3am. What's it like working at a very small startup when I'm not in the first 3 employees? You can tell if it's going to be more-but-okay (50-60 hours a week) or unsustainable (70+) by talking to the founders. Most small venture-funded companies will optimize their hiring around single people willing to take long hours for less pay and the hope of a payout. What's it like founding a company? It is what you make of it. You absolutely should expect some absolutely booked weeks. It'll be awful. It may or may not be worth it. In summary: the larger the company the more time upper management will put in and the more normal hours everyone else gets to work.