Note: Employees are paid on commission for extra baggage fees collected at the gate. 10%. I learned this after this flight. I flew with a personal-item sized bag that I have used repeatedly with no issues. On 12/30/2025 I was flying from Las Vegas to Dallas with this bag. Every passenger who did not pay for a carryon bag and only had a personal item was forced to wait in a long line to put their bag into the bag checker. All the while, someone would intermittently announce that the door was going to be closed for the flight we were all boarding. Everyone was stressed; people were trying to rearrange things in their bags. One older man tried to point out that another passenger was boarding with a bag identical to his as a personal item and the employees completely ignored him until, with no other option, he paid when he should not have had to. The person he had pointed out had a carryon as well as that identical bag as their personal item and those passengers did not have to check any bag sizes. So that poor old man just paid like we all did.
On the flight to Las Vegas from Dallas, I flew with this same bag packed in the same manner on Spirit (yes, Spirit) and it fit into their bag checker. Here's the thing: on the web site, Frontier and Spirit cite the same dimension requirements. So perhaps Frontier has altered their bag checkers? I heard multiple passengers who were not only frustrated but confused. They had flown with their bags multiple times and had no issue, just like me. Fly any other airline - even Spirit, if you really need to save money. But whatever you do, don't fly Frontier.
The instructions indicate to also share positive aspects. I tried to think of one and here it is: We did not crash.