Synapse 19

Tom Bihn Synapse 19 is a 19L, 0.7kg1.5lb travel backpack measuring 41×29×20cm16×11.5×8in. It fits the carry-on size limit of 36 of 36 major airlines and the personal-item limit of 8 of 26. Under the seat, its 41cm16.1in side is over the 40cm15.7in limit at 12 of the 18 airlines it misses. Specs from tombihn.com, checked September 2026.

Volume: 19Lfixed size
Weight: 0.7kg1.5lb1.5lb0.7kg
Carry-on: 36/36airlines fit it
Personal item: 8/26under-seat limits

Dimensions: 41×29×20cm16×11.5×8in 16×11.5×8in41×29×20cm
Price: $255 as of September 2026
Laptop: up to 13"
Opening: Panel access, half-zip
Warranty: Lifetime Fixes faults free of charge, wear and tear repairs are done at a reasonable charge.
Compartments: 6
Bottle pockets: 1

Price history

$255 at every weekly check since Oct 5, 2026 (3 checks).

Checked weekly on the brand's US store.

Water-resistant
Hip belt
Sternum strap (removable)
Shoulder strap

Material: 420d Spectron ripstop exterior (default), 210d Cerylon interior, closed-cell foam back panel

Fits a 13" laptop via built-in Cache-pouch attachment loops (not an internal padded sleeve)
Five exterior pockets total, including one center 32oz water-bottle pocket
Includes a Gatekeeper waist strap and a removable 0.75" sternum strap
Eight internal O-rings for organization; water-repellent YKK zippers

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Last checked: 2026-09. Prices and specs may have changed.

Does the Tom Bihn Synapse 19 fit airline carry-on limits?

Draw against

Cabin bag, tight (no spare)Cabin bag, tight (no spare) 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	Tight fit (no spare)Tight fit (no spare)	Too bigToo big	6.3kg to pack (of 7kg)13.9lb to pack (of 15.4lb)
Air CanadaCabin bag not on every fare	FitsFits	Too bigToo big	No published limitNo published limit
Air FranceCabin bag not on every fare	FitsFits	Too bigToo big	11.3kg to pack (of 12kg shared with personal item)24.9lb to pack (of 26.5lb shared with personal item)
Air India	Tight fit (no spare)Tight fit (no spare)	No published limit	6.3kg to pack (of 7kg)13.9lb to pack (of 15.4lb)
AirAsia	FitsFits	Too bigToo big	6.3kg to pack (of 7kg shared with personal item)13.9lb 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	Tight fit (no spare)Tight fit (no spare)	No published limitNo published limit
American Airlines	FitsFits	Tight fit (no spare)Tight fit (no spare)	No published limitNo published limit
ANA (All Nippon Airways)	FitsFits	Too bigToo big	9.3kg to pack (of 10kg shared with personal item)20.5lb to pack (of 22lb shared with personal item)
AviancaCabin bag not on every fare	FitsFits	No published limit	9.3kg to pack (of 10kg)20.5lb to pack (of 22lb)
British Airways	FitsFits	Tight fit (no spare)Tight fit (no spare)	No published limitNo published limit
Cebu Pacific	FitsFits	Too bigToo big	9.3kg to pack (of 10kg shared with personal item)20.5lb 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	Tight fit (no spare)Tight fit (no spare)	14.3kg to pack (of 15kg)31.5lb to pack (of 33.1lb)
Emirates	FitsFits	No published limit	6.3kg to pack (of 7kg)13.9lb to pack (of 15.4lb)
Frontier AirlinesCabin bag not on every fare	FitsFits	Tight fit (no spare)Tight fit (no spare)	15.2kg to pack (of 15.9kg)33.5lb to pack (of 35.1lb)
Gol Linhas Aereas	FitsFits	No published limit	9.3kg to pack (of 10kg)20.5lb to pack (of 22lb)
IndiGo	FitsFits	No published limit	6.3kg to pack (of 7kg)13.9lb to pack (of 15.4lb)
JetBlue Airways	FitsFits	Tight fit (no spare)Tight fit (no spare)	No published limitNo published limit
KLMCabin bag not on every fare	FitsFits	Too bigToo big	11.3kg to pack (of 12kg shared with personal item)24.9lb to pack (of 26.5lb shared with personal item)
LATAM Airlines	FitsFits	Tight fit (no spare)Tight fit (no spare)	11.3kg to pack (of 12kg)24.9lb to pack (of 26.5lb)
LufthansaCabin bag not on every fare	FitsFits	Too bigToo big	7.3kg to pack (of 8kg)16.1lb to pack (of 17.6lb)
Norwegian Air ShuttleCabin bag not on every fare	FitsFits	Too bigToo big	9.3kg to pack (of 10kg shared with personal item)20.5lb to pack (of 22lb shared with personal item)
Qantas	FitsFits	No published limit	6.3kg to pack (of 7kg shared with personal item)13.9lb to pack (of 15.4lb shared with personal item)
Qatar Airways	FitsFits	No published limit	6.3kg to pack (of 7kg)13.9lb to pack (of 15.4lb)
RyanairCabin bag not on every fare	Tight fit (no spare)Tight fit (no spare)	Too bigToo big	9.3kg to pack (of 10kg)20.5lb to pack (of 22lb)
SAS	FitsFits	Too bigToo big	7.3kg to pack (of 8kg)16.1lb to pack (of 17.6lb)
Singapore Airlines	FitsFits	Too bigToo big	6.3kg to pack (of 7kg)13.9lb to pack (of 15.4lb)
Southwest Airlines	FitsFits	No published limit	No published limitNo published limit
Turkish Airlines	FitsFits	Too bigToo big	7.3kg to pack (of 8kg)16.1lb to pack (of 17.6lb)
United AirlinesCabin bag not on every fare	FitsFits	Too bigToo big	No published limitNo published limit
Vietjet Air	FitsFits	Too bigToo big	6.3kg to pack (of 7kg shared with personal item)13.9lb to pack (of 15.4lb shared with personal item)
VolarisCabin bag not on every fare	FitsFits	Tight fit (no spare)Tight fit (no spare)	9.3kg to pack (of 10kg)20.5lb to pack (of 22lb)
VuelingCabin bag not on every fare	Tight fit (no spare)Tight fit (no spare)	Too bigToo big	9.3kg to pack (of 10kg)20.5lb 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	9.3kg to pack (of 10kg)20.5lb 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 0.7kg1.5lb. Limits and sources. Own a different bag? Check it against every airline.