The charge will apply to bags in the overhead bin. Personal items that fit under the seat will still be free. Spirit Airlines said it will add measuring devices at the gates to determine which carry-ons are free and which ones will incur the charge.
The new charge is $45 if paid at the gate, and $30 if paid in advance, and begins Aug. 1. Spirit said on Tuesday that it reduced its lowest fares by $40 on average, so most customers won't really pay more to fly.
Spirit also charges to check luggage.
The low-cost carrier is the first to charge for carry-on bags. Beginning August 1, passengers will pay to stow a piece of luggage in the overhead bin. Personal items that fit under the seat will be free. Some say the new fee will help reduce the number of carry-ons, which has greatly increased since most airlines began charging for checked luggage.
In the spirit of keeping their faces low, Florida-based Spirit Airlines plans to charge passengers as much as $45 each way for a carry-on bag. It is a plan that outrages loyal customers like John Red and his wife. They fly from O'Hare to Fort Myers several times a year.
"Once they start charging we won't be flying Spirit. We always fly Spirit, but this will be the last one if they do it," said Red.
While Spirit Airlines is a small airline, and the first to charge for carry-on luggage, industry experts say the major airlines will be watching closely to see whether Spirit customers are willing to pay the carry-on fee.
Travelers have no doubt major carriers will at some point charge for carry-on bags as well.
"They are following suit. One does it, then the others follow," said one passenger.
"It is a competition thing," said another.
Besides keeping its fares low, Spirit Airlines believes carry-on fees will reduce the number of carry-on bags onboard. Ever since the major airlines began charging fees for checked luggage, the Association of Flight Attendants says the number of carry-ons has skyrocketed, which has caused major problems, the union says, especially in the days of reduced staff and the push to leave on time.
"People start rushing, and they start hurrying to try to move things around. That's when we find the greatest number of injuries with baggage. Flight attendants get injured. Passengers get injured," said Jeffrey Heisey, Association of Flight Attendants.
Passengers say the carry-on situation onboard has become challenging for them as well.
"They're pretty full all the time, and it wasn't even that full of a flight," said Jenny Powell, passenger.
"Onboard, everyone is pushing, shoving trying to get their cases in there. It is a real nightmare trying to keep your bags with you," said David Birkley, passenger.
Many travelers long for the good old days.
"I can remember when you used to be able to go onboard, fly somewhere, they give you a real nice meal, and they give you a drink, and they made you feel like you were welcome," said Red.
Experts say, unless passengers are willing to pay much higher fares, it is unlikely the fees will go away.
To help with the carry-on crunch, Chicago-area Congressman Daniel Lipinski has introduced legislation limiting the size of bags that can be brought into the cabin.
Southwest and Jet Blue are the only airlines that do not charge for one checked bag.
The Associated Press contributed to this report.