The company, based in the Samoan capital Apia, is the first to bring in the controversial measure that means overweight passengers pay more for their ticket.
A statement from Samoa Air said: "We at Samoa Air are keeping airfares fair, by charging our passengers only for what they weigh.
"You are the master of your air 'fair', you decide how much (or little) your ticket will cost. No more exorbitant excess baggage fees or being charged for baggage you may not carry. Your weight plus your baggage items, is what you pay for. Simple."