The filing made Tuesday seeks compensatory damages from the company and a change in practices.
Plaintiffs' lawyer Stephen DeNittis says the company should either make their sandwiches 12 inches long or stop advertising them as footlongs.
He said he's measured sandwiches from 17 area shops and not one has been 12 inches long.
Subway did not immediately return a call to The Associated Press.
The issue got widespread attention last week when a man posted a photo of a sandwich and a ruler on the company's Facebook page.
More than 100,000 people have "liked" or commented on the photo, which has the caption "Subway pls respond." Lookalike pictures have popped up elsewhere on Facebook. And The New York Post conducted an investigation that found four out of seven footlong sandwiches were shy of the 12 inches that makes a foot.
Last week Subwaysaid that the length of its sandwiches may vary slightly when its bread, which is baked at each Subway location, is not made to the chain's exact specifications.
"We are reinforcing our policies and procedures in an effort to ensure our offerings are always consistent no matter which Subway restaurant you visit," Subway said in an e-mailed statement.