U.S. airlines earned more than $4.6 billion in checked baggage fees last year.

In fact, most airlines seem focused on generating more and more revenue from ancillary fees than even basic airfares.

And how much — per passenger — are we talking about?

In Australia, Qantas makes about $59 in extra charges per passenger.

In the U.S., Spirit Airlines rakes in about $73 per passenger in fees, followed closely by Allegiant.

Why am I telling you this? It’s not because you can necessarily avoid it, unless you’re flying with absolutely no bags, but to help you budget better every time you fly.