I’m confused about the capacity figures that backpack manufacturers claim. With daypacks it seems that the figures advertised are always about 20 percent higher than what the pack actually holds. What gives?Submitted by - Jeanne Fort Collins, CO
I agree it can sometimes be confusing and frustrating when looking at cubic inch capacities. Years ago, I was so annoyed by the figure discrepancies that I decided that BACKPACKER would publish our own, confirmed cubic inch numbers. So I created a big wooden contraption and filled it with ping pong balls. For each pack we reviewed, I loaded it with the balls, then dumped them back into the container to measure them.
It was a pain in the ass (balls bouncing all over the place) but it worked. Since then the industry has agreed to a standardized way of measuring internal volume using 20mm plastic balls.
If you need something to read tonight to put you to sleep, check this out.
Technically the numbers should be correct. But really, what’s most important is whether your gear fits inside, not based on the number on the hangtag. It’s a drag, I know, but the best thing to do is bring your gear to the store with you when you shop. It’s the only way to know for sure whether it’s the right size to haul your stuff.