TransformerX 4.0 UltraLight Packable Backpack 15L

Waterfly TransformerX 4.0 UltraLight Packable Backpack 15L is a 15L, 0.19kg0.4lb travel backpack measuring 40.6×24.1×15.2cm16×9.5×6in. It fits the carry-on size limit of 36 of 36 major airlines and the personal-item limit of 10 of 26. Under the seat, its 40.6cm16in side is over the 40cm15.7in limit at 12 of the 16 airlines it misses. Specs from waterflyshop.com, checked October 2026.

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Volume: 15Lfixed size
Weight: 0.19kg0.4lb0.4lb0.19kg
Carry-on: 36/36airlines fit it
Personal item: 10/26under-seat limits

Dimensions: 40.6×24.1×15.2cm16×9.5×6in 16×9.5×6in40.6×24.1×15.2cm
Price: $19.99 as of October 2026
Laptop: n/a
Opening: Zippered main compartment
Warranty: 10 years 10-year limited warranty for registered members buying direct; guests 3 years.
Compartments: n/a
Bottle pockets: 2

Material: Tear-resistant, wear-resistant nylon

Folds into its own inner pocket, 6 x 8 x 1.5 in
Breathable mesh shoulder straps

Last checked: 2026-10. Prices and specs may have changed.

Does the Waterfly TransformerX 4.0 UltraLight Packable Backpack 15L fit airline carry-on limits?

Draw against

Fits as a cabin bagFits as a cabin bag on Ryanair. cabin bag 55×40×20cm21.5×15.5×8in · under the seat 40×30×20cm15.5×12×8in. Bag in cminches, turned to fit.

Flag as a tight fit undercm spare

Airline	Carry-on	Personal item	Cabin-bag weight
Air Arabia	FitsFits	Too bigToo big	6.8kg to pack (of 7kg)15lb to pack (of 15.4lb)
Air CanadaCabin bag not on every fare	FitsFits	Tight fit (0.8cm spare)Tight fit (0.3in spare)	No published limitNo published limit
Air FranceCabin bag not on every fare	FitsFits	Too bigToo big	11.8kg to pack (of 12kg shared with personal item)26lb to pack (of 26.5lb shared with personal item)
Air India	FitsFits	No published limit	6.8kg to pack (of 7kg)15lb to pack (of 15.4lb)
AirAsia	FitsFits	Too bigToo big	6.8kg to pack (of 7kg shared with personal item)15lb to pack (of 15.4lb shared with personal item)
Alaska Airlines	FitsFits	No published limit	No published limitNo published limit
Allegiant AirCabin bag not on every fare	FitsFits	FitsFits	No published limitNo published limit
American Airlines	FitsFits	FitsFits	No published limitNo published limit
ANA (All Nippon Airways)	FitsFits	Too bigToo big	9.8kg to pack (of 10kg shared with personal item)21.6lb to pack (of 22lb shared with personal item)
AviancaCabin bag not on every fare	FitsFits	No published limit	9.8kg to pack (of 10kg)21.6lb to pack (of 22lb)
British Airways	FitsFits	FitsFits	No published limitNo published limit
Cebu Pacific	FitsFits	Too bigToo big	9.8kg to pack (of 10kg shared with personal item)21.6lb to pack (of 22lb shared with personal item)
Delta Air Lines	FitsFits	No published limit	No published limitNo published limit
easyJetCabin bag not on every fare	FitsFits	FitsFits	14.8kg to pack (of 15kg)32.6lb to pack (of 33.1lb)
Emirates	FitsFits	No published limit	6.8kg to pack (of 7kg)15lb to pack (of 15.4lb)
Frontier AirlinesCabin bag not on every fare	FitsFits	FitsFits	15.7kg to pack (of 15.9kg)34.6lb to pack (of 35.1lb)
Gol Linhas Aereas	FitsFits	No published limit	9.8kg to pack (of 10kg)21.6lb to pack (of 22lb)
IndiGo	FitsFits	No published limit	6.8kg to pack (of 7kg)15lb to pack (of 15.4lb)
JetBlue Airways	FitsFits	FitsFits	No published limitNo published limit
KLMCabin bag not on every fare	FitsFits	Too bigToo big	11.8kg to pack (of 12kg shared with personal item)26lb to pack (of 26.5lb shared with personal item)
LATAM Airlines	FitsFits	FitsFits	11.8kg to pack (of 12kg)26lb to pack (of 26.5lb)
LufthansaCabin bag not on every fare	FitsFits	Too bigToo big	7.8kg to pack (of 8kg)17.2lb to pack (of 17.6lb)
Norwegian Air ShuttleCabin bag not on every fare	FitsFits	Too bigToo big	9.8kg to pack (of 10kg shared with personal item)21.6lb to pack (of 22lb shared with personal item)
Qantas	FitsFits	No published limit	6.8kg to pack (of 7kg shared with personal item)15lb to pack (of 15.4lb shared with personal item)
Qatar Airways	FitsFits	No published limit	6.8kg to pack (of 7kg)15lb to pack (of 15.4lb)
RyanairCabin bag not on every fare	FitsFits	Too bigToo big	9.8kg to pack (of 10kg)21.6lb to pack (of 22lb)
SAS	FitsFits	Too bigToo big	7.8kg to pack (of 8kg)17.2lb to pack (of 17.6lb)
Singapore Airlines	FitsFits	Too bigToo big	6.8kg to pack (of 7kg)15lb to pack (of 15.4lb)
Southwest Airlines	FitsFits	No published limit	No published limitNo published limit
Turkish Airlines	FitsFits	Too bigToo big	7.8kg to pack (of 8kg)17.2lb to pack (of 17.6lb)
United AirlinesCabin bag not on every fare	FitsFits	Tight fit (0.9cm spare)Tight fit (0.4in spare)	No published limitNo published limit
Vietjet Air	FitsFits	Too bigToo big	6.8kg to pack (of 7kg shared with personal item)15lb to pack (of 15.4lb shared with personal item)
VolarisCabin bag not on every fare	FitsFits	FitsFits	9.8kg to pack (of 10kg)21.6lb to pack (of 22lb)
VuelingCabin bag not on every fare	FitsFits	Too bigToo big	9.8kg to pack (of 10kg)21.6lb to pack (of 22lb)
WestJetCabin bag not on every fare	FitsFits	Too bigToo big	No published limitNo published limit
Wizz AirCabin bag not on every fare	FitsFits	Too bigToo big	9.8kg to pack (of 10kg)21.6lb to pack (of 22lb)

Compared in any orientation against each airline's published size limit. A tight fit has under 2cm to spare, so a packed soft bag may not pass a sizer. Set it to 0 to turn the warning off. Weight is what the airline allows in the cabin minus this bag's empty 0.19kg0.4lb. Limits and sources. Own a different bag? Check it against every airline.