Spirit Airlines will charge as much as $45 each way for a carry-on bag, adding a fee that bigger airlines have yet to try.

The charge will apply to bags in the overhead bin. Personal items that fit under the seat will still be free.

The new charge is $45 if paid at the gate, and $30 if paid in advance. It begins Aug. 1.

Spirit says a new fare reduction means most customers won't really pay more to fly. It says having fewer carry-on bags will help empty the plane faster. Spirit also charges to check luggage.

Spirit mostly flies out of Florida to Latin America. Even though it's a minor player, bigger airlines are likely to watch to see whether customers are willing to pay for carry-ons.