Bruce Gonzalez and John Morrow stopped for lunch last week at a Miami McDonald’s, each ordering a Quarter Pounder with Cheese, large fries and a large Coke.

“I’m guessing it’s about 500 to 600 calories,” Gonzalez said.

“Yeah, that’s about right,” Morrow agreed.

Wrong.

The furniture delivery men were consuming more than double that amount: a whopping 1,320 calories.

“Now I’ve got to run 40 times around the block,” said Gonzalez, 55.

Neither man noticed that the new counter listed the caloric count of each item — right next to the price — at the McDonald’s at Northeast 35th Street and Biscayne Boulevard.

By Monday, all of the nearly 14,000 McDonald’s in the United States will have this nutritional information posted on the drive-through and behind-the-counter menus.

McDonald’s Corp., the world’s largest food chain based in Oak Brook, Ill., is making the nationwide move ahead of a new regulation that is in the works under the Affordable Health Care Act. That regulation calls for all restaurant chains with more than 20 locations to post calorie counts on their menus.

Panera Bread was the first major chain to do so in April 2010. But most other major chains await the exact details of the regulation and timetable for implementation.

Jan Fields, president of McDonald’s USA, said in a press conference last week that the company wants to do it “voluntarily” because it will help educate their customers. The company already provides the calorie content on menus in Australia, South Korea and the United Kingdom.

And while the calorie information has been available to McDonald’s North American customers for years on its website and some of its food wrappings, seeing the numbers on the menu is an eye opener for many.

“Wow,” said Linda Rose as she saw that the McCafe chocolate shake with whipped cream that she was about to order would set her back 710 calories.

That’s about one-third of the total calories a moderately active woman aged 26 to 50 should consume in an entire day, according to recommendations by the U.S. Food and Drug Administration.

Rose thought for a minute and instead chose the real fruit smoothie — at 350 calories for the large size.

Some recent studies have shown that posting calories does little to change what customers choose to order. But that was not the case for most of the McDonald’s customers who were randomly asked last week.

Ron Butler, who works at a nonprofit that helps drug addicts and the homeless, said the calorie content does influence his decision making: “I have weight issues.”

Still, that didn’t stop him from eating a Big Mac (540 calories), French fries (380 calories) and a Diet Coke (zero calories) for lunch.

“I feel less guilty with the Diet Coke and the Big Mac was buy one get one free today,” he said. “I’ll save the second one for tomorrow’s lunch. But I guess it’s still almost 1,000 calories. I know I splurged at noontime, so at nighttime I’ll eat less.”

McDonald’s often is blamed by nutritionists and health experts as a big reason Americans are getting fatter. In the United States, about one third of adults and 17 percent of children are considered obese, according to the national Centers for Disease Control and Prevention.