redearslider.com

I've read a million articles about proper tank size for turtle size. Some say 10 gallons per inch, others say minimum height and width should be 1.5-2 times shell length. Which is better?

I think considering that tank sizes are not uniform across brands the formula would be more accurate. Thoughts?

The water volume rule is in large part because of nitrate build up. You don't want too much nitrate in your water, so the more water you have to dilute the resulting nitrate, the better your turtle.

The measurements are for turtle comfort. The 1.5 times shell length is so your turtle can turn over--so it doesn't end up upside down under water without the space to right itself. The length is so it can at least do some swimming.

Personally, I'd say that minimum width should be much greater.

I try to follow both. I believe what I read was 1.5-2 times for height, but 5 times for length.
The height/length rules basically define the shape of the tank. To me they say how the turtle can comfortably swim. For instance a tall hex tank may hold lots of water, but if the turtle really wants to swim over a distance, they would have to go vertically.

There were a few different "calculations" for tank sizes back when I started this site. I went with the 10 gallon "rule" as it was more generous and easy to remember. More water for the turtle is a great thing... consider what they are supposed to have out in the wild.

A key point that ljapa brought up is to have a minimum. Spork brings up a good point too. One time someone put a pic of their turtle in a hex tank and the people flipped out. It's also why we say breeder tanks are great for turtles.

ok that makes sense