Most listings are in the $30's per square foot per year. The Fairfax County region is experiencing a a rise in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 2% increase in rent.
In the last 90 days, 31 listings have been made available, which means new listings are probably leasing quickly. You'll want to be prepared to tour spaces as quick as possible. About 194% of the office spaces in the Fairfax County are subleases, so you might be able to snag a great spot on a short term. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,230 sqft. Most buildings in this area are close to 3 stories. Most buildings in this area were built in 1985 and are Class B.