Size does matter – and two New Jersey men are suing to prove it.

The pair have sued Subway, saying the world’s biggest fast-food chain has been shorting them on its so-called footlong sandwiches.

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.

DeNittis, the lawyer for the plaintiffs in the New Jersey suit, said he’s seeking class-action status and is also preparing to file a similar suit in Pennsylvania state court in Philadelphia.

He said he’s had sandwiches from 17 shops measured — and every one came up short.

“The case is about holding companies to deliver what they’ve promised,” he said.

Even though the alleged short of a half-inch or so of bread is relatively small, it adds up, he said. Subway has 38,000 stores around the world, nearly all owned by franchisees and its $5 footlong specials have been a mainstay of the company’s ads for five years.

DeNittis said both plaintiffs — John Farley, of Evesham and Charles Noah Pendrack, of Ocean City — came to him after reading last week about the short sandwiches.

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.

The Milford, Conn.-based firm should either make sure its sandwiches measure a full foot or stop advertising them as such.

He points to how McDonald’s quarter-pounders are advertised as being that weight before they are cooked.

Subway did not immediately return a call to The Associated Press on Wednesday.

Earlier this month, The Post discovered that the city’s lunchtime crowds were getting short-changed after a muckraking Australian revealed the company’s famous “Five-dollar Footlongs” were smaller than advertised.

Four out of seven Footlongs — purchased at Subway locations in Manhattan, Brooklyn and Queens — measured only 11 or 11.5 inches, according to the test.

And that’s not the only corner Subway is cutting — the shops have sliced their cold-cut sizes by 25 percent in the past few months, a Manhattan franchise owner told The Post.

“The distributor has increased the food cost on the individual owners by 4 to 5 percent every year and provided the owners with less food,” the owner explained.

Smaller heroes and less meat have fired up loyal regulars — who now have a different kind of beef.

“They’re cheating us!” said 32-year-old Juan Rivera, who runs a hardware shop in Brooklyn Heights.

He eats Subway every other day with his father — but now he feels betrayed.

“That’s foul and misleading. They state it’s a foot long, so it should be a foot long!”

His regular Subway shop in Brooklyn Heights — on Montague and Henry streets — sold The Post a $6.75 “Italian BMT” that measured only 11 inches.

And those extra few bites can really add up.

If you buy a $7 “footlong” every other day for a year, an axed extra inch adds up to a loss of roughly $100.

Others at the Brooklyn Heights outpost were more concerned with waistlines than bottom lines.

“It’s probably good that it’s not a whole foot long — I don’t think anybody needs a full foot-long sandwich,” sniffed Margaret Zakhary, 30.

A meatball sub and an “oven-roasted” chicken sub from two shops on the Lower East Side measured in at 11.5 inches. So did a “Cold Cut Combo” from Long Island City.

The lunch drama came after Australian Matt Corby posted a photo of a turkey sub next to measuring tape on the company’s Facebook Page on Tuesday.

Corby’s photo — showing the sandwich at 11 inches — went viral, garnering more than 118,000 “likes” in just 24 hours.

Some defended the “shrinkage,” saying toasted subs come out shorter — but The Post’s analysis didn’t bear that out.

Subway Spokesman Les Winogad said at the time that the photo “doesn’t meet our standards.”

“We always strive for our customers to have the most positive experience possible,” he added.