With Spirit gone in 2026, Frontier is one of the last major ultra-low-cost carriers standing in the US market, and its $19 promotional one-way fares keep pulling people in. But comb through Reddit, Tripadvisor, Facebook threads and consumer blogs and the same gripes surface again and again. Here's what travellers report — and what you can do about it.

The biggest complaint is the à la sticker shock. A base fare gets you a randomly assigned seat and one small personal item. Everything else costs extra, and often more than on major airlines: a carry-on added online runs around $70 on Frontier versus $35 on United. The workaround is to price your bags with Frontier's tool before booking, consider a bundle, and compare the all-in total against a legacy carrier's basic economy. Frequently, they're closer than you'd think.

Then there's the personal-item bin. Frontier's limit is 14 by 18 by 8 inches, straps and wheels included, and enforcement is inconsistent — one Tripadvisor user was charged $100 because a backpack strap poked out of the sizer. Measure your packed bag at home and don't overstuff it; hoping for a lenient gate agent is not a strategy.

Checked bags catch people out too. Since early 2022 Frontier's weight limit has been 40 pounds, not the 50 you get on Delta, United, American or Southwest. Bags between 41 and 50 pounds cost an extra $75, and 51 to 99.99 pounds costs $100. A $10 portable luggage scale solves this problem before it starts — and leave room for souvenirs.

Disruptions are where Frontier's thin route network really bites. Some cities see a Frontier flight only once or twice a week, so a missed connection can mean days of waiting. The airline doesn't guarantee hotels, meal vouchers or rebooking on other carriers, and one Reddit user spent two nights in a hotel after a weather delay in Denver. If you have a wedding, conference or cruise to catch, don't gamble on Frontier. Customer service adds to the pain: travellers report dropped chats, unanswered phones and agents who can't help. If you do have to call, have your confirmation number ready and ask for a specific resolution rather than an open-ended complaint.

Onboard, expect thin, non-reclining seats with minimal padding — no pillows or kits, either. Regulars suggest a neck pillow and some in-seat stretching for anything over an hour. UpFront Plus seating gets you extra legroom and an empty middle seat, but after paying for it, the maths may no longer favour Frontier. And if you skip paid seat selection, your group can get split up; families who want to sit together should budget for assignments.

None of this makes Frontier a bad deal in every case. For a short, direct flight on a flexible schedule with a backpack that fits the sizer, cheap fares can be exactly that. The consistent message from frequent flyers: know every fee before you book, pack conservatively, and never book Frontier for a trip with a fixed, can't-miss commitment.