Confused by airline bag fees? Not sure what “basic economy” means and how much extra you’ll pay for bags, carry-ons or seat assignments? You’re not alone. Airlines have made it increasingly difficult to determine how much you’ll end up paying for a given ticket.

We created this calculator to help make sense of basic economy fares and the fees you’ll pay to add on things like bags or seat selection. It includes ways to offset these add-on fees, such as airline branded credit cards and elite status.

You can use the calculator to help determine which ticket will actually be cheaper. For example, if United is charging $100 for a round-trip ticket in basic economy and Southwest is charging $150 for its economy cabin, the calculator can show which fare is really cheaper for you (hint: It’s probably Southwest).

It also shows the tradeoffs in price and convenience of booking basic economy fares. For example, United charges $25 each way for overhead carry-ons in basic economy, but such fees are waived when booking with most branded credit cards.

Some important notes:

The calculator only applies to flights within the United States. International bag fees are different for most airlines.

These fees are subject to change. We’ll update the calculator when airlines announce changes, but make sure to check the official policy for your fare before booking a ticket.