Spirit Airlines has the highest hidden fees of any US carrier - making trips 736 percent more expensive than their base airfare, a new study has revealed.

The budget airline adds an average of $161.12 on top of a fare of just $21.89, according to analysis by discount code website NetVoucherCodes, the highest increase of any airline in the world.

Volaris, a Mexican low-cost airline, has the second highest hidden fees, according to the study. The hidden costs are 626 percent of the original airfare, asking customers to pay $82.20 on top of a $13.13 flight.

It comes after the Government pledged to crack down on hidden 'junk' fees in February, which the White House estimates cost Americans around $65 billion every year.

Customers are routinely promised a headline sum, only to find the true cost is much more expensive once they taken into account the price of baggage, seat selection and insurance - which often costs much more than the flight itself.

Customers are routinely promised a headline sum, only to find the true cost is much more expensive once they taken into account the price of baggage, seat selection and insurance - which often costs much more than the flight itself

Spirit Airlines has the highest hidden fees of any US airline - making the flight 736 percent more expensive, a new study has revealed

NetVoucherCodes built a list of the world's top airlines and curated a route for each one which left on the same day and resulted in roughly the same amount of time in the air.

The study then calculated how much was added to the airfare for services like carry-on baggage, checked bags, seat selection, fast track, insurance and onboard WiFi.

Frontier had the third highest hidden fees as it adds $109 to a $29 base airfare on average - making the journey 376 percent more expensive.

Sun Country Airlines, an ultra-low cost carrier which offers flights across the US, Mexico, Central America and the Caribbean, came in fourth place.

The airline added $98.48 to a $49 flight - an increase of 201 percent.

Sun Country Airlines said that when customers book a trip, they are given pricing for additional services.

'As a budget airline, we have customers who simply choose to purchase their flight and travel light without any extras. Other customers like the ability to make choices about whatever is important to them on flights,' a spokesperson said.

Delta Air Lines, meanwhile, came in fifth place, with fees increasing the fare by 158 percent - including a $30 charge for seat selection.

As part of the Junk Fee Prevention Act, President Joe Biden specified that he wants to axe fees for family members to sit with young children.

'I will prohibit airlines from charging $50 round trip for a family just to be able to sit together. Baggage fees are bad enough. Airlines can't treat your child like a piece of baggage,' the President said in February.

According to figures from the Transport Department, passengers forked out $5.3 billion in baggage fees alone in 2022.

It found that aviation companies also cashed in a further $700 million in cancellation and flight change charges last year.

Volaris, a Mexican low-cost airline, has the second highest hidden fees, according to the study

President Joe Biden used his State of the Union speech in February to highlight his war on junk fees - the hidden charges used by companies to screw more cash out of consumers

According to figures from the Transport Department, passengers forked out $5.3 billion in baggage fees alone in 2022

On average, the study found, US airlines charge $78.04 in hidden fees. European carriers, on the other hand, charge an average of $57.79, while international carriers charge $33.27.

While budget airlines tend to charge more in hidden fees - rather than incorporating them into the cost of the airfare itself - major carriers also add costs on top.

United Airlines added $67 in hidden costs - increasing the overall price by 122 percent, according to the study, while American Airlines added $52 in hidden fees - bringing up the total by 95 percent.

Rebecca Bebbington, a money travel expert at NetVoucherCodes, said there are a couple of strategies you can use to help ensure your air travel stays cheap.

'To avoid baggage fees, try fitting all your belongings into a carry-on bag,' she said. 'These tend to be free with budget airlines but be sure to pack strategically to avoid overweight baggage fees.

'You should also research the seat selection fees of different airlines. Consider skipping seat selection during booking and try selecting seats for free during online check-in, within the 24-hour window.

'If you're traveling in a group, book tickets together to increase the chances of being seated together without paying extra for seat selection,' she added.