According to Frontier's website, your personal item will be checked during boarding and is subject to an additional charge if it's larger. Frontier will also weigh and measure your checked bags when you check in, so make sure your checked bags meet the size and weight requirements.
Checked bags weighing 41-50 pounds will result in a fee of $50 per bag, per direction, while checked bags weighing 51-100 pounds will result in a $100 fee per bag, per direction. Bags over 100 pounds are not accepted.
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