A thin jacket or sweater would fit in the bag. With a laptop on board it would be a tight fit. Without a laptop, it should be no problem. There would be some, but not too much room for a lot of other things, however. (This is based on my using the bag with a MacBook. With a MacBook Air - there would likely be more space - I just saw a MacBook Air in person last week and it is amazingly thin but feels incredibly sturdy.