Boundary Supply Prima vs. Tom Bihn Brain Bag
Two carry-on travel backpacks, compared spec for spec.
Boundary Supply Prima
| Capacity | 30 L |
| Weight | 1.9 kg |
| Dimensions | 53×31×18 cm |
| Airline fit | 88% |
| Price | $319 |
Feature by feature
| Boundary Supply Prima | Feature | Tom Bihn Brain Bag |
|---|---|---|
| Storage | ||
| 2 | Compression | 4 |
| None | Expanded Capacity | None |
| 3 | Opening | 4 |
| top | Passport | top |
| Y | Passthrough | N |
| Carry | ||
| Y | Backpack | Y |
| removable | Hip Belt | removable |
| removable | Sternum Strap | removable |
| Inside | ||
| 16in | Laptop | N |
| 0 | Main Compartments | 6 |
| Y | Organizer | Y |
| Outside | ||
| × | Hard Shell | × |
| N | Rain-fly | N |
| 1, side | Water Bottle Holder | 1, side |
| Y | Water Resistant | Y |
| Material | |
| 500D Kodra Nylon YKK StormGuard | 525 Ballistic Nylon |
Tom Bihn Brain Bag
| Capacity | 36 L |
| Weight | 1.3 kg |
| Dimensions | 46×36×23 cm |
| Airline fit | 66% |
| Price | $240 |
Key differences between the Boundary Supply Prima and Tom Bihn Brain Bag
- Compression straps: 2 on the Boundary Supply Prima; 4 on the Tom Bihn Brain Bag.
- Opening: Top flap on the Boundary Supply Prima; Top zip on the Tom Bihn Brain Bag.
- Luggage passthrough: Yes on the Boundary Supply Prima; No on the Tom Bihn Brain Bag.
- Laptop sleeve: 16in on the Boundary Supply Prima; No on the Tom Bihn Brain Bag.
Both have: passport pocket, backpack straps, hip belt, sternum strap, built-in organizer, water bottle pockets, water resistant.
Which airlines take each bag as a carry-on
We checked both bags against the carry-on size limits of 189 airlines. 120 accept both. 47 accept only the Boundary Supply Prima, and 5 accept only the Tom Bihn Brain Bag.
Only the Boundary Supply Prima fits
Aerolineas Argentinas, Air Baltic, Air China, Air France, Air India, Air Malta, Air Mauritius, Air Serbia, Air Seychelles, Asiana Airlines, ATA Airlines, Blue Air, Boliviana de Aviacion, Bulgaria Air, Cayman Airways, China Eastern, Emirates Airlines, Enter Air, flybe, Icelandair, Indigo, InselAir, Jet Airways, Juneyao Airlines, Kenya Airways, KLM, LATAM , Liat Airlines, Luxair, Meridiana Fly, Nordwind Airlines, Pakistan International, Royal Brunei Airlines, Ryanair, S7, Shandong Airlines, Shenzhen Airlines, Sky Airlines, Sun Express, TAP Air Portugal, TAROM, Tianjin Airlines (A320 & E190), TUI, Ukraine International, VIM Airlines (Closed), Volotea, Xiamen.
Only the Tom Bihn Brain Bag fits
Etihad Airways, Oman Air, Qatar Airways, Ravn Alaska, Royal Jordanian.
Boundary Supply Prima vs. Tom Bihn Brain Bag: which should you pack?
The Tom Bihn Brain Bag carries 6L more than the Boundary Supply Prima (30L vs. 36L), while the Tom Bihn Brain Bag is the lighter pack at 1.3kg (vs. 1.9kg). For carry-on flexibility, the Boundary Supply Prima fits 88% of the airlines we track — the higher of the two. If you prioritise packing volume, choose the Tom Bihn Brain Bag; if you want to travel lighter, the Tom Bihn Brain Bag is the better call.