Just a bag and the credit card fee can be £82. We look at the real cost of budget flights

Holidaymakers travelling to Europe this summer on budget airlines face soaring fees for taking just a single bag on the plane – and staggering costs if they have to make any changes to their tickets or discover at the airport that their bag weighs too much.

Ryanair's new "high season" rate of £70 return for a 20kg bag to go into the hold comes into force in June and lasts to October, with an £80 charge if you're heading to the Canaries, Greece or Cyprus.

If you don't book online, but turn up at the airport with your bag, the fee rises to a staggering £130 one way.

Meanwhile, passengers on easyJet this summer face a charge of up to £32 for a 20kg suitcase on a return flight, up from £28 last summer, while Aer Lingus has hiked its bag charge from £24 to £36 return.

A Money survey of budget airlines' add-on charges reveals that it can cost £100 to take your golf clubs, £110 to change the name on a ticket, £30 for extra leg room and £120 because your bag weighs 3kg over the limit.

What's more, we found car hire offered by the "low-cost" airlines to be much pricier than rates that could be found elsewhere. But we were surprised to find ultra-cheap (basic cover) single-trip travel insurance offered by an airline, Jet2.com, that beat anything we could find searching elsewhere.

Total add-ons table Photograph: Graphic

We researched costs at Aer Lingus, British Airways, CityJet, easyJet, Jet2, Flybe, Monarch, Ryanair and Thomson. Given the recent takeover of BMI by British Airways, we did not test bmibaby, its low-cost offshoot, which is due to close in September.

Ryanair was the highest cost airline for bags, credit card fees, name change fees, flight change fees, fees for taking on special items such as golf clubs, and even the fee for sending a passenger a text to tell them about the flight. It's £1.50 at Ryanair and £1 everywhere else.

But easyJet, Jet2 and Aer Lingus have each introduced general "administration" fees which are slapped on to all flights, although quite what this covers is not made clear.

Jet2 also charges a fee for online check-in (£10 return) which, along with its other charges, makes the Leeds/Bradford-based airline second only to Ryanair in the add-on costs league (click on main picture for full table).

But Ryanair and Jet2 are by no means alone in imposing significant extra costs on travellers lured by the promise of low-cost flights.

When we tested costs for a one-week return flight for one person this summer to Malaga (in the case of Aer Lingus and CityJet we used London to Dublin), we found add-on costs of £34.95 at Thomson, rising to £58.10 at Jet2 and £82 at Ryanair. CityJet was the only airline to charge nothing whatsoever in add-ons. British Airways limited its add-ons to a £4.50 fee for paying by credit card.

The card surcharges are a huge moneyspinner for the airlines. The Office of Fair Trading found that UK consumers spent £300m on payment surcharges to airlines in 2010 and, in December 2011, the government said it would ban "excessive" card fees from the end of 2012. But that comes too late for travellers this summer and, in any case, may be circumnavigated by the airlines.

Ahead of the planned government crackdown, Ryanair no longer calls its £6 per-person-per-flight card fee a card fee. Instead, its site refers to the charge as an "administration fee" which "relates to costs associated with Ryanair's booking system".

For a family of four paying with a debit or credit card, the fee adds £48 to the holiday cost.

Navigating the add-on costs is a confusing business. Some airlines charge flat-rate fees, while others charge rates based on the total cost of the flight.

But the underlying cost of the flight may, for many people, still swing the equation in favour of Ryanair.

For example, the cheapest return on Ryanair from London to Malaga we could find, flying out at peak time this summer, on Saturday 4 August, returning one week later, was £146.22, but £188.98 on easyJet. However, if the traveller takes a 20kg bag, the price advantage over easyJet disappears.

Beware flying Ryanair if you are planning on taking your golf clubs or any sports equipment. The airline now charges £100 return to carry golf clubs – more than the cost of taking a human on many of its flights.

Other airlines surveyed by Money charged between £50 and £60, although CityJet takes them for free.

It can make for some interesting price comparisons. For example, Ryanair gives the cost of a one-week return from London to Dublin as just £40.98 in mid-June. But this jumps to £222.98 once the traveller takes a 20kg bag for their week away and brings their golf clubs.

CityJet charges a much higher base cost of £182.13, four times the price of Ryanair, but as bags and golf (or other sports equipment) go free, it's cheaper to take CityJet.

Most airlines now push partner deals on car hire, hotels and travel insurance, which are mostly poor value, except for Jet2's single-trip insurance.

Ryanair came out cheaper than other airlines on the car hire it sells to travellers when they are making a booking.

In our survey, we found that Ryanair wanted £92 for the hire of a basic car at Malaga airport for a week, compared to the £125 quoted by Flybe and £109 by easyJet.

But even though it was cheaper, don't be lured into buying. For the same period, car hire booked through holidayautos.co.uk at Malaga airport was £72 for a Ford Ka, £77 for a Corsa, and £100 for a Ford Focus.

Travel insurance is another minefield. The budget airlines use every tactic possible to scare passengers into buying, and usually make it something that has to be "unchecked" before proceeding with a booking.

Cheapest was Jet2's £5 offer for a week in Malaga, a third of the price of easyJet's deal. It even compares well with the best deals available by searching on the likes of MoneySupermarket.com.

But you get what you pay for – Jet2's cover for theft of personal belongings is limited to £500 and it has a £100 excess. Still, if you are just looking for basic protection against catastrophes such as medical claims, it's good value.

Flying with a budget airline can save the traveller money, but largely by foregoing a bag and by accepting that once the ticket is bought, there can be no changes. Jet2 even bills itself as a "no-refund" airline.

If you do make changes after booking, the costs are eye-watering. Again, Ryanair tops the table of charges. If a traveller inputs the wrong name during online booking or wishes to change the name on a ticket at a later date, Ryanair will charge as much as £160 at the airport, or £110 online. Other airlines tend to charge £70-£80.

And woe betide the traveller who arrives at the airport with their bag bulging. If it is three kilos overweight it will cost £60 at Ryanair (one way) and £30 at easyJet.

Travellers who try to dodge Ryanair's fees by stuffing their carry-on luggage to the limit are also taking a financial risk. The airline has a flat £50 fee for oversized cabin baggage.

Most travellers can also wave goodbye to their money if they have to cancel, and should claim on their travel insurance instead if it is the result of the death or serious illness of a partner.

Infants under two, travelling on a parent's lap, have to pay £40 return on easyJet, Jet2 and Ryanair, even though they are not taking a seat. On very cheap flights, it can mean the baby pays more than the parent.

The "full service" airlines, such as British Airways, came out well in the survey, although BA introduced budget airline-style advance seat reservation charges in 2009, much to the dismay of regular travellers.