Much like Jerry's pad on "Seinfeld" or Monica's rent-controlled apartment on "Friends," the Los Robles apartment building is usually the focal point of the action on "The Big Bang Theory." Apartment 4A — home to Sheldon Cooper (Jim Parsons) and Leonard Hofstadter (Johnny Galecki) — was full of laughter, heartfelt moments, and .
As far as apartment buildings go, Los Robles wasn't too shabby. The units had exposed brick, there was laundry in the basement, and Pasadena City Hall was a stone's throw away. Sure, the elevator didn't work, leading to plenty of , but that was Leonard's fault owing to a rocket fuel experiment gone wrong, as explained in Season 3's "The Staircase Implementation."
It's worth considering, then, what Sheldon and Leonard are coughing up monthly to live in their apartment. According to a recent for a two-bedroom apartment in the real-life Los Robles Apartments building, the unit rents for $3,411 a month (adjusted for inflation, that number would be lower in 2007 when "The Big Bang Theory" premiered. That's slightly above average for two-bedrooms in Pasadena, the median rent of which is $3,250. However, with their cushy jobs, Sheldon and Leonard could more than afford it.
The main characters' salaries on "The Big Bang Theory" aren't discussed much, perhaps because money isn't an issue for scientists in their respective fields. The median pay for a theoretical physicist can be around $62,534 to $82,000, but for someone of Sheldon's renown, it could be much higher. He later becomes an assistant professor at the California Institute of Technology, the salary of which can run anywhere from just under six figures to $160,000 depending on experience. Likewise, Leonard wasn't hard-up for cash. As an experimental physicist, he'd likely be pulling in six figures as well, since the median salary is about $120,000.
In other words, Leonard and Sheldon probably didn't need to live together at all, at least from a financial standpoint. Then again, money can't buy a readily available Mystic Warlords of Ka'a opponent.
While Sheldon and Leonard could have afforded one-bedrooms in the Los Robles apartment building, then it's who could have used a roommate. As a waitress at The Cheesecake Factory, she was making considerably less than her neighbors, though 4B was a smaller unit than 4A. "The Big Bang Theory" at least was realistic about her relative financial precarity, showing her mooching off of her neighbors' internet and food, as well as borrowing money.