One of least popular policies has gained traction with another airline, a consumer watchdog has revealed. The Irish air carrier’s policy of charging passengers extra for that doesn’t fit under the in front of them has been picked up by one of the UK’s most popular budget airlines.

now also charges its passengers a fee for putting an item in the overhead locker of a cabin. The fee starts from £5.99 per flight, essentially the same as Ryanair’s fee that begins at £6 and can go up to £36.

With Ryanair, passengers are able to pay to check in either a 10kg or 20kg piece of luggage. Contrastingly, easyJet offers a range of luggage options between 15kg, 23kg or 32kg. Again, the prices vary by route.

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The £5.99 easyJet base fee covers the cost of stowing a , the maximum dimensions of which are: 56 x 45 x 25 cm. This cabin bag must be able to fit in the baggage gauge and an overhead locker to avoid additional charges for storage as check-in luggage.

If you are debating between the two carriers, the UK consumer champion, , has evaluated both airlines based on their . According to Which? Ryanair's baggage allowance is the least generous when compared to many.

The budget airline’s Basic fare only entitles passengers to one, small bag which must fit under the seat in front of them. Ryanair’s regular fare entitles passengers to priority boarding and two cabin bags, including an additional 10kg case that can be stowed in the overhead locker. This fare class can cost anywhere from £6 - £36 if chosen when booking, or £20 - £60 if you add it at a later date.

Which? recommends Ryanair passengers select the basic fare and include extra services and bags in their booking as needed. Opting for add-ons as opposed to choosing the more expensive bundled fare that includes and priority boarding is often a more cost-effective option.

When it comes to easyJet, Which? confirmed Standard ticket holders will need to pay extra for anything beyond a small, underseat bag (measuring 45 x 36 x 20 cm including any handles and wheels, weighing a maximum of 15kg).

But while easyJet offers a Standard Plus fare that includes a large cabin bag, Which says passengers may be able to get a better deal by choosing a Standard fare, and adding cabin bags manually, as is the case with Ryanair.

That said, the consumer researcher recommends comparing prices on two different browsers or devices to see what’s cheaper. You can find a full list of each airline and their free baggage allowances (including weight and volume) below:

• British Airways: 56 x 45 x 25 plus handbag/laptop bag; weight 23kg; volume 63 litres

• easyJet: 45 x 36 x 20 (underseat bag only); weight 15kg; volume 32.4 litres

• Jet2: 56 x 45 x 25 plus handbag/laptop bag; weight 10kg; volume 63 litres

• Ryanair: 40 x 20 x 25 (underseat bag only); weight 10kg; volume 20 litres