I'm going against the crowd to say this is an OK bag. It's great for its price, but overall it's still just an ok bag. It definitely isn't 40L, not even close. I'd put it at closer to 30L. Someone on YouTube did a fill test and I think it came to 32L. I can barely fit a 20L backpack plus a set of Bose headphones inside of this. The top also does not have much structure so it deforms under weight and scrunches anything in the top zipper compartment. The bottom has a folding piece to help with this problem. Overall, I debated hard about returning it, but kept it. It's what I would expect from a budget bag, so it meets expectations at best (aside from empirically less than 40L).