30L v 40L backpack

Not sure what kind of outdoor stores you have in the Tri-Cities but if you are in Spokane over the holiday season you could go to the REI there and have them help you with a pack that fits your body better. It's at the corner of Monroe and Boone.

thanks Pam we do have REI here as well of course it's not a big as the one in Spokane :( .

Personally, I would start the selection process by deciding what dimensions you were aiming for, rather than volume. While dimensions will dictate volume to a certain extent (depends on configuration and other form factors), the airlines don't care one whit about what volume your bag has. They care about its dimensions (and in some cases, they also care about its weight, but you can control that).

It's worth noting that there is no universal standard for all airlines. So you need to figure out which airline is the most strict that you are likely to care about and aim for the dimensions they dictate. Volume is secondary. At least for me, I have no idea what the volume of my pack is, and don't really care...dimensions are everything.

I have also been considering a 30 or 32 liter bag. I have the Rick Steves backpack and it’s a little one for me. I’m considering these bags:
https://www.amazon.com/Hynes-Eagle-Convertible-19x12x7-5-Approved/dp/B06XK1P2CP?ref_=ast_sto_dp&th=1&psc=1 This is 28 liter so it’s a little smaller than I want.

https://www.amazon.com/Backpack-Mengar-Foldable-Resistant-Packable/dp/B01IQL7LHO/ref=sr_1_51?crid=36HYOJU6ZS0OY&dchild=1&keywords=30%2Bliter%2Bbackpack&qid=1574805737&sprefix=30%2Bliter%2Bba%2Caps%2C189&sr=8-51&th=1 This is quite lightweight but I’m wondering if it could work.

I’m interested in hearing other options.

How about gathering all the items you plan to take, put them in a clean plastic bag, and take this bag to an REI store. This way both you and the REI staff associate can find a suitable backpack and frame that will fit you and your "stuff". REI has a very liberal return policy. If you find several bags on line, order them and if they are not a good fit, just return them to the store for a full refund. If you have to, spend all day at an REI store trying on the diverse backpacks that might interest you. The packs both my husband and I use are the rei-co-op-ruckpack-40. The 40L does not meet the carry on limit if you pack them completely full. We have never been questioned at the airport but we do not pack them full. We are very happy with them. Best of luck choosing the correct backpack!

I pack light. But, I think 30 liters is really pushing it. I would stay with 37 - 40 liters. I don't need a bag right now. However, I like Eagle Creek migrate for dimensions. I believe the osprey Porter is about 30 liters. A simple cube bag with a couple backpack straps should do the trick. Consider Patagonia.

The switch from 40L to 30L is a 25% reduction in volume, equal to about 2-1/2 gallons of milk. You may have room in your Osprey but do you have THAT much empty volume? My summer packing list fits easily into my Tom Bihn Aeronaut 30L but my usual travel pack is a Patagonia MLC45L. (The 45L is never full, plenty of room to pack easily and to cope with the unexpected.)

The decision to use a carryon backpack can be based on one’s need for stomping over difficult terrain or a simple matter of traveling style and convenience. Most travel backpacks do not have suspension systems designed for extensive hiking like the Osprey.

What do you need your backpack to do for you?

If you are just carrying casual clothes in packing cubes/ditty bags - consider the 27 liter Patagonia Black Hole, Ultralight Tote Pack. There's a video about it on the Patagonia website. Versatile. Not too expensive compared to other options. Could work well for you.

thanks everyone!