Allegiant Air: standard limit is 40 lb per bag — overweight or oversized bags cost extra on top of the regular baggage fee.
Want the full guide? Get a PDF with tips for avoiding overweight fees on Allegiant Air — free.
41-70 lb: $50-75 extra, per bag.
Over 70 lb: not accepted at all — repacking into a second bag is your only option at the airport.
Over 62 linear inches: an additional oversize fee applies.
Allegiant's standard weight limit is lower than legacy carriers (40 lb, not 50) — a bag that's fine on Delta can already be overweight here.