The words “overweight luggage” have the power to induce a whirlwind of stress and embarrassment for holidaymakers. But one airline is upping the stakes by inviting passengers to step on the scales too.

The Finnish airline Finnair started the voluntary weighing in policy at departure gates at Helsinki airport on Monday with the aim of enabling it to better estimate the weight of its planes’ cargo before takeoff.

To the airline’s surprise, by Wednesday it had already had 600 volunteers.

While Finnair insists passengers are not penalised for their weight, and that the numbers are kept discreet, away from prying eyes, they are not hugely compensated for sharing it either. Those who agree to take part are thanked for their efforts with a small gift of a reflective baggage tag.

Suvi Aaltonen, a Finnair spokesperson, said: “Our customers have taken it really positively so far. We’ve been quite surprised by people wanting to take part.”

Despite each aircraft having a fixed maximum weight that cannot be exceeded if it is to be safe to fly, the weight of passengers and their carry-on luggage is usually only based on average passenger weights updated every five years.

The weight of the passenger and their hand luggage is recorded as one number. The results of the weigh-ins, set to continue until May, will be sent to the Finnish transport and communications agency, Traficom, and used for aircraft balance and loading calculations from next year until 2030.

Satu Munnukka, the head of ground processes at Finnair, said the measurements were being collected for safety purposes and were “not linked in any way to the customer’s personal data”.

Munnukka added: “We record the total weight and background information of the customer and their carry-on baggage but we do not ask for the name or booking number, for example. Only the customer service agent working at the measuring point can see the total weight, so you can participate in the study with peace of mind.”