Nearly a year since Samoa Air started charging passengers by weight, the airline says the experiment has been a huge success.

Samoa Air made headlines when it became the first airline in the world to charge people in such a way.

Samoa Air's Chief Executive Chris Langton says the trial has been so successful that aircraft will continue to be modified to work under the pay-by-weight system.

"The profile that we would use for the next aircraft, we would bring it from 14 seats which would be its traditional layout and we'll actually only put in nine seats," he told Pacific Beat.

"And that way we can provide for people who are paying more because they are larger.

"And everybody gets what they're paying for."

Mr Langton says customer feedback during the first year of the policy has been positive.

"Initially people do the sums," he said.

"They just compare what they would pay on a pay-by-weight system and just do basic arithmetic.

"We find that generally speaking if you look at any operation anywhere between any destination worldwide, a person that comes in at about 120 kilos or less will always be better off to travel on a pay-by-weight system."

The system works where a passenger's body weight and baggage weight are added together to give a total weight and price.

Mr Langton says the system is the way of the future for airlines.

"Everything will be done by weight and continues to go that way," he said.

"The interest level hasn't diminished anywhere.

"Worldwide there's still massive discussion going on as to how pay-by-weight is going to transcend into larger aeroplanes."

The airline says it benefits from the pay-by-weight system because it can be more precise with filling aircraft to their maximum capacity and therefore more efficient.