Confused on container volumes

[happycamper15]

Hi all,

I am quite confused about container volumes.
I understand most containers/pots are labeled in terms of the "trade" volume.

According to Home Depot's webpage, a trade gallon for nursery pots is approximately 0.71 US liquid gallons.
"Please note that our pots are measured in trade gallons. A Trade gallon is a term used to denote the sizes of standard plant containers in horticultural industries. A trade gallon is equal to approximately .71 U.S. liquid gallons."

A US liquid gallon is 231 cubic inches, meaning a trade gallon would be about 164 cubic inches (0.71*231)?

Yet the Home Depot "1 gallon" pots are 6" tall, and 7" diameter,
meaning the volume would be 230.79 cubic inches. (3.14*3.5^2*6)

This is one US liquid gallon? Is the difference due to the small taper of the container? I find that hard to believe.


Anybody see my confusion?

 

[Iron_Lion]

Pots are a bitch.

Last grow I went out and bought 20 3 gal smart pots, got them home filled them up and ran the grow. A few months later I bust out my old 3gal plastic grow bags and I realize they have the same diameter of the smart pots but the smart pots are 6-7 inches shorter. One of them has to be off, my guess is one of them is liquid gal and the smart pots must be trade gal. i wont be using the smart pots again, they just don't hold enough soil.

 

[badmf]

I disagree you may need bigger smart pots, but...the reason they are smart is the pots use more center pot soil, yes?