Measuring carry-on luggage: how to check a packed underseater
- 8 min reading time
Measure your carry-on after packing, including handles, pockets, and protruding parts. Compare each exterior dimension with your ticket.
Short answer: measure your carry-on after you have packed and closed the bag. Take the largest external dimension in each direction, including handles, wheels, straps, zippers, and bulging pockets. Then compare each dimension and the weight separately with what is allowed for your flight and ticket. Liters or an empty product size are not enough.
First determine: free bag under the seat or larger cabin luggage?
A small bag that must fit under the seat is different from larger cabin luggage for the overhead compartment. With budget airlines, usually only the small item is included as standard. A trolley or larger travel bag may require a separate booking, a different fare, or priority. Therefore, first check your booking confirmation and then the airline's current baggage page.
Want to see the airlines side by side? View the current comparison of free underseat carry-on luggage at Ryanair, Transavia, easyJet, and Wizz Air.
Measure carry-on luggage in six steps
- Pack the bag as you intend to travel with it. Close all zippers and use an expandable zipper only if you also use it during the flight.
- Position or lay the bag in the most favorable real orientation. You may only turn it if the fully packed bag can fit in a measuring box and under the seat in that position.
- Measure the longest side. Start at the outermost point and include protruding parts.
- Measure the second external dimension. Measure straight from outermost point to outermost point, not along the curve of the fabric.
- Measure the maximum depth. Do not artificially flatten a bulging front pocket. The size while traveling counts.
- Weigh the bag completely. Use the weight allowed for your ticket; a suitable size does not automatically make an overweight bag allowed.
A simple way is to place the bag against a wall and mark the outermost points with two straight objects. Measure the rectangle that the entire bag fits into. This way, you do not accidentally overlook a bulging top or protruding buckle.
Why a soft underseater may be larger after packing
A soft travel bag may fit within the specified dimensions when empty, but may still become too deep when filled. Especially clothing in the corners, a full side pocket, and shoes against the bottom change the external shape. Therefore, do not measure only the rigid bottom surface. Also check the top and the thickest pocket. A soft bag may give, but it must still fit entirely within the limit and inside the baggage sizer.
The order of dimensions is not a free pass
A dimension like 40 × 30 × 20 cm is often displayed as height × width × depth. A bag can sometimes be turned, but only the actual external shape counts. For example, the catalog dimension 40 × 20 × 25 cm may be compared as 40 × 25 × 20 cm when the packed bag can actually be placed that way. That is a mathematical comparison, not a guarantee at the gate.
Current size limits to compare with your measurement
Checked on October 21, 2026. Always re-check your booking and the official page before departure:
- Ryanair: one small personal bag of maximum 40 × 30 × 20 cm, under the seat.
- Transavia: one piece of carry-on luggage of maximum 40 × 30 × 20 cm and maximum 10 kg, under the seat.
- easyJet: one small bag of maximum 45 × 36 × 20 cm, including handles and wheels, maximum 15 kg and carried by hand.
- Wizz Air: one free small bag of maximum 40 × 30 × 20 cm and maximum 10 kg, under the seat.
These short checkpoints do not replace the conditions of your ticket. Larger cabin luggage has different dimensions and is not included with every standard ticket.
Compare the dimensions of our travel bags
These are catalog dimensions. Measure the fully packed bag and compare all sides with the conditions of your ticket.
MONOO
Grey travel bag 40 × 30 × 20 cm
Soft polyester travel bag with five zippered compartments for clothing and travel essentials.
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MONOO
Weekend bag 40 × 20 × 25 cm
Compact weekend bag with multiple compartments and a separate shoe compartment. Available in pink and black.
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MONOO
Black backpack 45 × 32 × 15 cm
Travel backpack with padded back panel, adjustable shoulder straps, and multiple zippered compartments.
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Compare three catalog dimensions from the current range
- The grey soft travel bag is listed in the catalog as 40 × 30 × 20 cm. After packing, check that no part extends beyond those dimensions.
- The MONOO weekend bag is registered as 40 × 20 × 25 cm. Compare the bag in an actual 40 × 25 × 20 orientation and measure again after filling.
- The black backpack is registered as 45 × 32 × 15 cm. This falls numerically within easyJet's current 45 × 36 × 20 cm, but not within a limit of 40 cm on the longest side.
These are supplier/catalog dimensions and not our own physical measurements. View all available shapes at Underseat Travel Bags.
Common measuring mistakes
- measuring only the empty bag;
- not including handles, buckles, or bulging external pockets;
- confusing capacity in liters with external dimensions;
- comparing only the largest dimension and forgetting the depth;
- confusing the free underseat bag with paid cabin luggage;
- relying on an old screenshot instead of the current booking.
Choosing further: weekend bag or backpack?
Do you have a soft travel bag? Then read when a weekend bag can count as free carry-on luggage. Would you rather carry it on both shoulders? Then view how to choose a backpack for under the airplane seat. The measuring method remains the same for both: pack, close, measure externally, and compare with your own ticket.
View bags per airline: Ryanair underseat bags, easyJet underseat bags, Transavia underseat bags, Wizz Air underseat bags.
Sources and rules checked on October 21, 2026. Airlines may change conditions.
Does your bag turn out to be too large after filling? Use the packing order for an underseater to identify bulging pockets and redistribute the contents before measuring again.