Manufacturers measure backpack volume differently—some use a mathematical calculation (H × W × D), while others use displacement methods (filling with beads to measure usable space). This often explains why stated and actual capacity don’t match.
Your old pack may feel bigger because:
Shape & Tapering: Some packs are taller/narrower, reducing usable space.
Padding & Structure: Reinforcements and curved backs take up internal volume.
Packing Density: Rigid containers leave gaps, while soft gear compresses to fill space.
Overstated Capacity: Some brands round up or include pockets in their total volume.
Aarn likely uses displacement-based measurements, making the Pace Magic 30 more compact than its dimensions suggest. If you’re struggling to fit your gear, consider a 35-40L pack or testing with more flexible packing methods.
I’ve written up a bit more info on this here: https://www.trailhiking.com.au/blog/decoding-backpack-volume-dont-be-fooled-by-the-numbers/
