Allegiant Vs. Spirit Vs. Frontier: Which American Low-Cost Carrier Charges The Most For Add-Ons?

Frontier Airlines, Allegiant Air, and Spirit Airlines are three leading low-cost or ultra-low-cost US carriers. Low-cost carriers are well known around the world for offering low fares but then charging numerous fees and additional costs for a wide range of upgrades and services. Famously, the hybrid giant Southwest Airlines, allowed free checked bags until 2025. However, these three low-cost carriers have long sought to generate additional revenue by levying fees on bags.