I can fit the exact same amount into a small bag as I can my big one, also, I can never find things in the big bag but can in the small one, its magic.......If travelling there is the functionality test, has to fit I pad, phone, make up, hairspray, brush, spare pants, deodorant or perfume, umbrella, purse, tickets if its the train and hopefully some food and drink, either a small flask or small bottle of water...and it must rest nicely on my shoulder and be fully zipped up to avoid loss of embarrassing spillage, I have followed my teenage daughter walking down the isle of a train dispensing Tampons from her unfastened ruck sack!!