If your looking for a travel camera bag then these reviews should tell you all you need to know as these are considered the Best Travel Camera Bags.
Remember your carry on luggage sizes differ between airlines
BA (55cm x 40cm x 23cm)
Ryanair (55cm x 40cm x 20cm)
Easyjet (45cm x 36cm x 20cm)
What type of Travel are you doing
The duration of your trip is often the first determiner of what you will need in a travel bag. While everyone has their own travel style, plus packing needs and comfort levels, generally trips can be classified by their length and what items you will need for the duration.
Day travel & commute: Protection is focused on a small mobile device such as iPad or iPhone 6 Plus, critical personal item and small amount of gear. Be nimble, light and flexible:
Overnight & short trips: Choose a bag with additional room for a change of clothes or more personal items, a few extra devices, business tools, etc. Keep it light, but don't sacrifice.
Multi-Day & trekking: Be prepared to pack multiple devices and their supporting accessories, batteries and cables, more than one bag (or a bag-in-a-bag), a larger amount of personal gear, and be prepared with the ability to handle several environments and situations. Take it with you… you'll probably need it.
TIP Buy a tripod that fits in the bottom of your suitcase then you can pack this in your hold luggage whilst keeping you precious camera kit in your hand luggage - as its usually the tripod that's the issue