Want to know where you’re sitting on your next flight? It’ll cost you.

Trying to reserve a seat these days is a logistical and financial puzzle unless you have airline status or corporate travel perks. Airlines have tricked-out seat maps with added fees nearly everywhere, even middle seats.

I’m not talking about budget airlines Frontier, Spirit and Allegiant, where passengers pay a fee to reserve a seat in advance in exchange for a cheap fare. I’m talking about rising seat fees at American, Delta and United, as anyone who’s booked a flight recently knows too well. Southwest doesn’t assign seats but does offer two options to board earlier for better seat selection. Those prices are also on the rise.

American was recently asking an extra $44 to $52 one way for a standard seat near the front of the plane for a flight from Dallas to New York this week and $29 to $35 for the same flight in June. I found prices ranging from $40 one way for an ordinary Delta seat to $90 for exit row on an Atlanta-Orlando, Fla., flight in June, and $51 for United flights from Newark, N.J., to San Francisco in May and June. All are labeled “preferred" seats by airlines.

On some flights, more economy seats have price tags than don’t. But you don’t discover the cost until you put in your passenger information. American shows you the price for each seat up front on the map. Delta and United each make you click individual seats to see prices. (The only thing you can see during a quick flight search is a seat map without prices to give you a general idea of seat availability.)

These days, a family pricing out a flight would need a calculator or spreadsheet to compare total flight prices. I know because I have spent hours pricing seats on some of their most popular routes the past few days. It was an exercise in frustration, and is overdue for change. Some lawmakers have mentioned seat fees in their push to get airlines to make the all-in cost of a plane ticket more clear upfront.

Yes, there were free seats available on every flight I checked, in some cases rows of them for June flights. All were in the back of the plane. In United’s case, the free seats were in rows 43 to 53 on a Boeing 777 on a Newark-San Francisco flight. Free seats get more scarce closer to departure.

B for billions

Airlines are playing to our travel anxieties and varying comfort levels with the seat upcharges, and clearly succeeding. Consultant Jay Sorensen of IdeaWorksCompany has studied airline ancillary revenue for years and estimates seat fees brought in $4.2 billion for eight large U.S. airlines on domestic flights alone in 2022. (His figure includes those cushy sections at the front of the economy cabin with names like Comfort Plus, Economy Plus and Main Cabin Extra.)

That compares with $5.1 billion for baggage fees, he says. Unlike bag and ticket change fees, the government doesn’t require airlines to disclose seat-fee revenue.

President Biden has called out airline seat fees in his campaign against junk fees, but only as it relates to charges so families can sit together.

United made the most public changes, pledging to seat kids 12 and younger with a family member without extra fees, even those on basic economy tickets. American and Delta said they have similar plans in place.

My unscientific search of seat fees for a family of four buying United basic economy tickets found three free seats together in the back row on a flight from Orlando to Newark on a Saturday in May. The fourth passenger would pay $25 for an adjacent seat. That compares with $88 for four standard basic economy seats together without the policy in place.

In a sign of just how lucrative seat revenue is, United says its family-seating guarantee has saved travelers nearly $40 million on more than 1.4 million preferred seats over the past year.

Tough European carriers

Beyond efforts to seat families together, airline seat fees show no signs of abating. Veteran fliers worry that U.S. airlines will adopt even more strict policies like some of their foreign competitors.

Cindy Culbertson, a retired bank regulator who lives in Virginia, is flying Scandinavian carrier SAS to Copenhagen this summer ahead of a 16-day Norway tour. In January, she found what she considered a great business class deal: $2,600 round trip.

When she got to the seat map, she was stunned to find a bunch of price tags for each lie-flat seat. Her seat bill: $250 round trip, including $10 on a short connecting flight.

“I said, ‘You’re kidding me,’" she says. She still paid to lock in the spot she wanted.

British Airways offers no free advance seat assignments to passengers without status, even if you’re flying business class. Passengers can pick a seat when they check in online 24 hours before their flight. (First-class passengers, families with infants and those with medical or accessibility issues can select a seat for free at booking, the airline says.)

Book a $6,200 round-trip British Airways business class ticket for a nonstop flight from Phoenix to London in June and you’ll pay $123 to $158 each way to pick your lie-flat seat at booking.

Gisele Lannamann and her husband paid $50 a person per leg for economy seats for round-trip tickets from Boston to Palma de Mallorca in Spain on Swiss in January.

Lannamann, a retired yacht chef, says they paid for seats so they could sit together in a window and middle seat.

Except they didn’t get the seats they paid for on the flight home. A text from the airline said they would be put in the best available seats. She says no one could help them at the airport or the gate and didn’t offer them a refund. They ended up separated.

They didn’t ask anyone to swap seats.

Want tips on getting the most for your money with seat assignments? I’ll share some in this week’s WSJ Travel newsletter. Sign up here.

Write to Dawn Gilbertson at dawn.gilbertson@wsj.com