A bigger seat — it’s what he craves.

A devoted, 290-pound White Castle fan is steaming mad at the fast-food chain, which he says repeatedly broke promises to make the booths in his local eatery bigger.

All stockbroker Martin Kessman wants is a place at the table. But when the 64-year-old walked into the White Castle in Nanuet back in April 2009 for his usual No. 2 combo meal, he got an unpleasant surprise.

“They’re stationary booths,” he told The Post. “I’m not humongous, [but] I’m a big guy. I could not wedge myself in.”

Mortified and in pain from smacking his knee into one of the table’s metal supports, Kessman limped out of the restaurant, and later penned a complaint to corporate headquarters.

“As I looked around the restaurant, I saw that there were no tables and chairs that could accommodate a person that merely wanted to sit down and eat his meal,” Kessman wrote.

Kessman claims he has no problem finding a place to take a load off at other fast-food places, and fits easily into airline seats.

White Castle replied with three “very condescending letters” — and an offer that added insult to injury.

“In each letter was a coupon for three free hamburgers — but the cheese was extra!” according to a lawsuit Kessman filed last week in Manhattan federal court.

But somehow, the humiliation didn’t dampen Kessman’s appetite for sliders at a discount.

“My wife went and picked up the burgers … because I did not want to set foot into the store,” he said. “Any subsequent trips to the store have been made by my wife — I have been like an outcast.”

White Castle also pledged to expand its seats, Kessman claimed.

“They sent me specs and everything, about how the booths were going to be enlarged and made comfortable for people with a little more weight,” Kessman said. “So two and a half years went by, and nothing was done.”

The Rockland County man says the chain’s uncomfortable booths violate the civil rights of fat people.

The Americans with Disabilities Act is “applicable, not only to me, but to pregnant women and to handicapped people,” he said.

“I just want to sit down like a normal person,” said Kessman, who is suing for bigger chairs and unspecified damages.

Kessman could have approached a store manager and asked for a regular chair, said White Castle spokeswoman Jamie Richardson, who had no timetable for the expected renovation of the Nanuet store.