---
url: "https://onebag.travel/compare/2rbg4dtslw/aer-travel-pack-4-35l/yshyt43faw/rei-co-op-trail-40/"
title: "Aer Travel Pack 4 35L vs REI Co-op Trail 40 - One Bag Travel"
description: "Aer Travel Pack 4 35L vs REI Co-op Trail 40: capacity, weight, dimensions and how many airlines accept each as a carry-on, side by side."
source: "https://onebag.travel/compare/2rbg4dtslw/aer-travel-pack-4-35l/yshyt43faw/rei-co-op-trail-40/"
---
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2.  [Carry-On Travel Backpacks](https://onebag.travel/carryons/)
3.  Aer Travel Pack 4 35L vs. REI Co-op Trail 40

# Aer Travel Pack 4 35L vs. REI Co-op Trail 40

Two carry-on travel backpacks, compared spec for spec.

## [Aer Travel Pack 4 35L](https://onebag.travel/carryon/2rbg4dtslw/aer-travel-pack-4-35l/)

by [Aer](https://onebag.travel/carryons/?brands=Aer)

![Front facing view of the Aer Travel Pack 4 35L](https://res.cloudinary.com/obt/image/upload/c_fill,w_400/v1788990469/carryons/aer-travel-pack-4-35l-2rbg4dtslw.webp)

<table class="table table-sm cmp-spec mt-2"><tbody><tr><td>Capacity</td><td>35 L</td></tr><tr><td>Weight</td><td>1.8 kg</td></tr><tr><td>Dimensions</td><td>55×34×23 cm</td></tr><tr><td>Airline fit</td><td>68%</td></tr><tr><td>Price</td><td>$260</td></tr></tbody></table>

## Feature by feature

| Aer Travel Pack 4 35L | Feature | REI Co-op Trail 40 |
| --- | --- | --- |
| Storage |
| N | Compression | 4 |
| None | Expanded Capacity | None |
| 1 | Opening | 1 |
| top | Passport | top |
| Y | Passthrough | N |
| Carry |
| Y | Backpack | Y |
| optional | Hip Belt | Y |
| removable | Sternum Strap | removable |
| Inside |
| 16in | Laptop | N |
| 5 | Main Compartments | 5 |
| Y | Organizer | Y |
| Outside |
| × | Hard Shell | × |
| N | Rain-fly | Y |
| 2, side | Water Bottle Holder | 2, side |
| Y | Water Resistant | Y |

<table class="cmp-material"><tbody><tr><td colspan="2">Material</td></tr><tr><td>1680D CORDURA® ballistic nylon exterior (bluesign® approved)</td><td>210-denier ripstop nylon</td></tr></tbody></table>

## [REI Co-op Trail 40](https://onebag.travel/carryon/yshyt43faw/rei-co-op-trail-40/)

by [REI Co-op](https://onebag.travel/carryons/?brands=REI Co-op)

<table class="table table-sm cmp-spec mt-2"><tbody><tr><td>Capacity</td><td>40 L</td></tr><tr><td>Weight</td><td>1.2 kg</td></tr><tr><td>Dimensions</td><td>56×30×23 cm</td></tr><tr><td>Airline fit</td><td>47%</td></tr><tr><td>Price</td><td>$130</td></tr></tbody></table>

## Key differences between the Aer Travel Pack 4 35L and REI Co-op Trail 40

-   **Compression straps:** No on the Aer Travel Pack 4 35L; 4 on the REI Co-op Trail 40.
-   **Luggage passthrough:** Yes on the Aer Travel Pack 4 35L; No on the REI Co-op Trail 40.
-   **Hip belt:** Optional on the Aer Travel Pack 4 35L; Yes on the REI Co-op Trail 40.
-   **Laptop sleeve:** 16in on the Aer Travel Pack 4 35L; No on the REI Co-op Trail 40.
-   **Rain cover:** No on the Aer Travel Pack 4 35L; Yes on the REI Co-op Trail 40.

Both have: passport pocket, backpack straps, 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. 88 accept both. 41 accept only the Aer Travel Pack 4 35L, and 0 accept only the REI Co-op Trail 40.

### Only the Aer Travel Pack 4 35L fits

Aer Lingus, Aeroflot, Aerolineas Argentinas, Aeromexico, Air Canada, Air Caraibes, Air France, Air India, Air Mauritius, All Nipon Airways, ANA, Austrian, Azerbaijan Airlines, Boliviana de Aviacion, Brussels Airlines, Czech Airlines, Ethiopian Airlines, Eurowings, Fiji Airways, Flair Air, Gol Linhas Aereas, Iberia, Indigo, Interjet, Iran Air, Japan Airlines, Jet Airways, Kenya Airways, KLM, LATAM , LOT Polish, Lufthansa, Mahan Air, Mesa Airlines, Norwegian, Peach, Porter Airlines, SAS Scandinavian, Sky Airlines, Swiss Int'l Air Lines, Turkish Airlines.

## Aer Travel Pack 4 35L vs. REI Co-op Trail 40: which should you pack?

The **REI Co-op Trail 40** carries 5L more than the **Aer Travel Pack 4 35L** (35L vs. 40L), while the **REI Co-op Trail 40** is the lighter pack at 1.2kg (vs. 1.8kg). For carry-on flexibility, the **Aer Travel Pack 4 35L** fits 68% of the airlines we track — the higher of the two. If you prioritise packing volume, choose the REI Co-op Trail 40; if you want to travel lighter, the REI Co-op Trail 40 is the better call.