Size matters: Which airlines are best for hand baggage?
Will it fit? The question, and the anxiety behind it, is familiar to every air traveller in the 21st century.
For who can say they have not inwardly trembled as an airline official directs them to the measuring cage - knowing they may face a hefty surcharge?
Such is the variation in the maximum dimensions for cabin baggage, that passengers might now logically chose to have a different suitcase for every airline.
According to a BBC survey of 17 major European airlines, the Spanish carrier Iberia is the most generous for cabin baggage, and the UK airlines Thomas Cook and Thomson are the meanest.
One surprise is that the low cost airline Ryanair is not at the bottom of the list, in spite of its previous reputation for high baggage and other charges.
Easyjet's position in the table is less clear cut.
It will allow a relatively large cabin bag, and is one of the few airlines not to impose a formal weight limit.
But passengers are also advised to take a smaller bag - to avoid the possibility of the bag being put in the hold at the last minute.
|Airline cabin baggage ranked by generosity|
|Airline||Maximum bag dimensions||Weight allowance|
|Iberia||56 x 45 x 25||Unlimited|
|British Airways||"||23 kg|
|Jet 2||"||10 kg|
|Flybe||55 x 40 x 23||10 kg|
|Scandinavian (SAS)||"||8 kg|
|Air France||55 x 35 x 25||12 kg|
|Virgin Atlantic||56 x 36 x 23||10kg|
|Ryanair||55 x 40 x 20||10 kg|
|Air Berlin||"||8 kg (10kg with laptop)|
|German Wings||"||8 kg|
|Thomas Cook||"||5 kg|
|Easyjet *||50 x 40 x 20 (guaranteed)||Unlimited|
|* Easyjet will take up to 56 x 45 x 25, but the case might have to go in the hold (for free) if not enough space|
Typically, carriers will let you stow a bag up to 55cm tall, 40 cm wide and 20 centimetres deep.
Remember these are not the sizes of the empty bag when you buy it. It has to fit the frame when fully packed - and that includes the handles or any other sticky out bits.
When it comes to the weight of your hand baggage, some airlines will allow you anything you can comfortably lift. Others allow just five kilogrammes.
And beware: Many older bags can weigh as much as five kilogrammes before you even put anything in them.
You may get away with it and breeze onto the plane with far more than you are allowed. But it is a risk. You could well have your dimensions tested at the gate - in which case breaking the well-advertised rules could land you with a hefty supplement of some £50.
Frank Brehany is the consumer director of HolidayTravelWatch, an organisation that aims to help holidaymakers with travel problems.
He says if anything there are too few checks being carried out at the gate. That is because out-sized bags can cause injury to other passengers.
"There have been occasions when consumers have reported an injury as a result of a heavy item falling down on arrival," he says.
"Others have been hurt because the owner cannot manage the weight of the bag. The weight can even cause the overhead bin to open."
To make matters worse, the rules are not always enforced consistently.
Sean Tipton from ABTA - the travel association - says it often depends on the airline staff member at the boarding gate.
"Some seem to be more lax than others, but you can't rely on that. Check out the policy first, because if you do get caught out we are talking about a substantial amount of money," he says.
The industry defends the inconsistency in hand baggage allowances, saying it is a direct result of the wide variation in the amount of space in the overhead bins on different aircraft. This argument is weakened by the fact that most carriers fly several different aircraft types.
But there is likely to be little appetite within the industry for uniform size restrictions.
"I am absolutely convinced the airlines would object to the proposal. And MPs and the government would support this," says Frank Brehany.
Nevertheless, to ensure it is not your luggage that is squeezed out when all the overhead lockers are full, do get to the boarding gate in good time.
Suffering the indignity of having to turn out your possessions in public - or even having them shoved into the hold at the last moment is not going to be the best start to your trip.