Chick-fil-A has kept its restaurants dark on Sundays for 80 years, and its chief executive says he has never even attempted to calculate how much revenue that sacrifice costs.

“I never have,” Andrew Cathy told NBC’s Today coanchor Craig Melvin in an Oct. 14 interview for the network’s “Business in America” series, when asked whether he had ever tallied the sales the chain gives up by staying closed one day a week. “And that’s being truthfully honest with you, I never have because it’s never something that we’re entertaining. It’s just too important for us.”

Cathy, the grandson of founder S. Truett Cathy, has led the privately held company since 2021, when he succeeded his father, Dan Cathy. He framed the policy as a luxury of family ownership. “We’re not trying to scrape out every penny that we possibly can,” he said. Being “a private business and a family business,” he added, means “we can make those types of investments because we know it means so much to our team members.” It is a tradeoff private, family ownership can absorb precisely because no outside investors are tallying the revenue left behind each Sunday.

A 1946 decision that stuck

The Sunday closure traces back to the chain’s earliest days. According to Chick-fil-A, S. Truett Cathy decided to close on Sundays in 1946, when he opened his first restaurant in Hapeville, Ga. Having worked seven days a week in restaurants that never shut, he wanted himself and his employees to have one day to rest, spend time with family, or worship if they chose.

“It was very common back in the 1940s that a lot of places were closed on Sunday,” Andrew Cathy said. “They wanted to have a chance to take a break—go to church, and for others just to take some rest.” The rule has survived every generational handoff since, from S. Truett Cathy to his son Dan to his grandson Andrew.

Exceptions have been exceedingly rare. In 2017, Fortune reported that Chick-fil-A opened on a Sunday to help feed travelers stranded at Atlanta’s Hartsfield-Jackson airport during a power outage. The company has also faced outside pressure, including a 2023 New York bill aimed at requiring restaurants at state highway rest stops to stay open seven days a week.

$23.9 billion in sales, six days a week

Whatever a seventh day might be worth, the chain has not needed it to grow. Chick-fil-A posted U.S. systemwide sales of $23.9 billion in 2025, up about 5% from $22.7 billion in 2024, according to its franchise disclosure document, as reported by QSR Magazine. That makes it one of only three U.S. restaurant brands with more than $20 billion in sales. The other two, McDonald’s and Starbucks, operate far more locations and are open every day of the week. For a company that answers to no public market, that is an unusual amount of open detail: federal rules require franchisors to hand these annual disclosure documents to prospective franchisees, which is how unit-level figures like these become public at all.

The company added a net 179 franchised and company-operated restaurants last year and ended 2025 with 2,863. That count excludes more than 400 licensed locations on college campuses in hospitals, and elsewhere. Chick-fil-A also permanently closed 18 restaurants, most of them freestanding stores. Consolidated revenue topped $10.3 billion—the smaller figure because it counts only what the parent company itself books, chiefly company-operated sales plus franchisee royalties and fees, while systemwide sales tally every dollar customers spend across all locations.

Where the chain stands furthest apart from rivals is per-store sales, though those numbers have cooled slightly since the pandemic-era surge. The roughly 2,300 freestanding and drive-thru-only restaurants that were open all year posted median sales of about $9.1 million in 2025. That is down from $9.2 million in 2024 and $9.3 million in 2023. The single highest-grossing restaurant brought in $20 million, up from $19.3 million the year before.

What a seventh day might be worth

Cathy may not have run the numbers, but others have. Analysts cited by Entrepreneur estimated in 2019 that the Sunday closure cost the chain at least $1.2 billion a year in sales. At the time, Chick-fil-A’s total sales were roughly half what they are today. A simple back-of-the-envelope calculation using 2025 figures—adding a seventh day at the same daily pace—would put the theoretical ceiling near $4 billion.

In practice, a seventh day would probably not deliver a clean one-sixth bump. Some Sunday demand already shifts to Saturday and Monday. Industry observers have also long argued that the closure works as a counterintuitive sales booster, because the scarcity has become part of the brand and helps drive traffic on the other six days.

The labor equation

Cathy also pointed to the people who run and staff the restaurants. Employees value having a guaranteed day off, he said, because it means “at least one day on the weekend I’m not going to have to go to work, which is great.”

Fast-food schedules often stretch across all seven days, so that promise sets the chain apart. It is also part of why running a Chick-fil-A is so sought after. Cathy said the company receives about 150,000 applications a year from people who want to operate a franchise, and it opens roughly 150 restaurants annually—about one operator seat for every 1,000 would-be franchisees. Opening on Sundays would mean asking operators and crews to give up the one day the company has guaranteed them for eight decades, and Cathy made clear he is not willing to ask. Future disclosures will show whether those median store volumes stabilize and how the licensed footprint evolves, while New York’s 2023 bill showed that legislatures, too, are willing to raise the Sunday question.

This story was originally featured on Fortune.com.