If you want to know how much fits in a backpack, the Liters is not the best metric for measuring.

Many potential customers like to look at the volume and then compare it with other backpacks, which of course makes sense.

However, there is no standardized method of volume measurement and these are therefore estimated only.
Many companies are very generous with these estimates.
Therefore, it often happens that a backpack with 20 liters can actually have the same volume as a backpack with 30 liters of another company.

What is the solution?

I would recommend Youtube reviews of people packing the backpack to see exactly how much actually fits into it.

Therefore I have uploaded many independent Youtube reviews on the website here.

Of course, if you have further questions about the capacity (or something else), I'll be glad to help you out ;-)