Subway customers can finally rest assured that their “Footlong” sandwiches will be as long as promised, after the chain agreed that the bread it uses will be at least 12 inches long.

The undertaking is part of the settlement of a class-action suit filed against the fast food chain after an Australian teenager in 2013 posted an image of his sandwich on Facebook that was only 11 inches long.

The image garnered international media attention, including an investigation by the New York Post, which found that four out of seven “Footlongs” it purchased in New York “measured only 11 or 11.5 inches.”

A judge had given preliminary approval in October to a settlement between Subway’s parent company and lawyers for the plaintiffs. Final approval was granted on 25 February.

As part of the settlement, Subway agreed to ensure that for at least four years its bread will be at least 12 inches long.

The judge approved $520,000 in lawyers fees and $500 for each of the 10 individuals who brought the class action, but no monetary claims were awarded.

“It was difficult to prove monetary damages, because everybody ate the evidence,” said Thomas Zimmerman, a lawyer for the plaintiffs.

Subway said in a statement that it was pleased the judge found no wrongdoing on its part.

“This allows us to move forward, without distractions, on our goal to provide great tasting sandwiches and salads, made exactly as each guest likes. We have already taken steps to ensure each guest receives the Footlong or six-inch sandwich they order,” the statement said.

Lynn Adelman, a judge for the US District Court Eastern District of Wisconsin, wrote in the final approval that the plaintiffs’ lawyers realised their claims “were quite weak” after an initial mediation session. Instead of trying to get monetary damages, he said plaintiffs decided to focus on injunctive relief requiring Subway to ensure its sandwiches are at least 12 inches long.

Adelman wrote that the plaintiffs’ lawyers learned that Subway makes its bread with “dough sticks” that weigh the same when they arrive at stores frozen. The dough is then thawed and stretched before baking, a process that can lead to variability in the size and shape of the resulting bread.

While the dough may have different shapes, it still has the same quantity of ingredients, Adelman wrote. The amount of meat and cheese is also standardised, but it’s possible that a shorter bread loaf might lead to a slightly less toppings. For instance, “a sandwich that was ¼-inch shorter than advertised might be missing a few shreds of lettuce or a gram or two of mayonnaise,” the judge wrote.

But Adelman also noted that sandwiches are made in front of the customer, who can ask for more toppings.

“Thus, the plaintiffs learned that, as a practical matter, the length of the bread does not affect the quantity of food the customer receives,” Adelman wrote.

Still, Subway agreed as part of the settlement to take steps to ensure its bread is at least 12 inches long, including requiring franchisees to “use a tool for measuring bread.”