There are a variety of ways to calculate how much office space you need including using my free office space calculator.

Once you have your own opinion on how much space you need, it’s always good to benchmark your need against similar users.

For instance, how does your need compare to the U.S. National Average? In Q3 2011, the national average was just shy of 360 SF per worker.

What about from an operating expense standpoint? Does it make sense to lease space at the most prestigious address in town? On average U.S. corporations spent around 2.2% of their operating budget on corporate real estate in 2010.

How about to your industry? The amount of office space you’ll need certainly depends on what industry you’re in. If your office environment is more of a back office or call center setting, you might be able to get by with 150 square feet per worker, but if you’re in sales or finance, most likely, you’re going to need 300 square feet or more per worker.

Sometimes, even the city you are in makes a difference, too. For example, Gateway cities like San Francisco, Boston and New York average over 400 square feet, but secondary markets like Salt Lake and San Diego average around 250 square feet per worker.

Leasing office space is a big financial, and usually long-term commitment. For this reason, it is always a good idea to benchmark the amount of office space you think you need, against these types of metrics.