What difference can an ounce make on an airplane?

If you are United Airlines, with 4,500 flights a day, an ounce can add up. The Chicago-based carrier said it recently began printing its inflight magazine, Hemisphere, on lighter paper, cutting 1 ounce from each magazine. It now weighs 6.85 ounces.

In an internal message to employees, United said it has also switched to lighter paper on its seatback service guides.

The carrier operates 744 mainline planes that vary in size, carrying 50 to 366 passengers each. For a typical 737 plane carrying 179 passengers, the reduction would mean about 11 pounds per flight.

The airline said that slight weight reduction is saving 170,000 gallons of fuel a year, or $290,000 in annual fuel costs.

Last year, United stopped on-board sales of duty-free items — such as perfumes, chocolates and liquor — cutting 1.4 million gallons of fuel a year at a cost savings of $2.3 million.