What you put in your herp's enclosure is very important, but did you know that the size of that enclosure is just as important? A reptile terrarium that is too small or too big can cause stress and negatively affect normal sleeping, eating, and behavioral patterns. This article will help you to figure out how to measure aquariums and terrariums and what size your herp needs.

Standard Tank Measurements
Many reference books and articles will recommend a minimum enclosure size in gallons, but what does that translate to in actual measurements?

Aquarium Capacity (in gallons)=	Terrarium Size (L x W x H)	Aquarium Capacity (in gallons)=	Terrarium Size (L x W x H)
5 gallons	16" x 18" x 10"	30 gallons	36" x 12" x 16"
10 gallons	20" x 10" x 12"	55 gallons	48" x 13" x 20"
15 gallons	24" x 12" x 12"	75 gallons	48" x 18" x 20"
15 gallon High	24" x 10" x 18"	90 gallons	48" x 18" x 24"
20 gallon High	24" x 12" x 16"	125 gallons	72" x 18" x 22"
20 gallon Long	30" x 12" x 12"	150 gallons	72" x 18" x 28"
29 gallons	30" x 12" x 18"	180 gallons	72" x 24" x 24"

If you are trying to calculate gallon size from the measurements of the enclosure, multiply the height by the width by the length to get cubic inches. To determine the size in US gallons, divide that number by 231. For example, if you have a terrarium that is 36" x 12" x 16", multiplying these numbers will give you 6,912. Divide that by 231, and you can see that it is a 30 gallon aquarium.

How big an enclosure do I need?
When figuring out how big a terrarium you will need, you need to know how big your reptile is. Take into consideration both its current size and what its adult size will be. Some reptiles, such as Green Iguanas and Red-eared Sliders, may be small when you purchase them, but they will get quite large. If you purchase an enclosure that is only big enough to properly house them when they are young, you will have to upgrade later. The various types of reptiles are measured differently to determine minimum enclosure size.

Lizard enclosures are measured based on "snout-tail length," or STL. The minimum enclosure size for one lizard is as follows:

• Length: 2 to 3 times the lizard's STL
• Depth: 1 to 1-1/2 times the lizard's STL
• Height: 1 to 1-1/2 times the lizard's STL (terrestrial)
              1-1/2 to 2 times the lizard's STL (arboreal)

Snake enclosures are based on their total length. The minimum enclosure size is:

• Length: 3/4 of the snake's total length
• Depth: 1/3 of the snake's total length
• Height: 3/4 of the snake's total length (terrestrial)
              1 times the snake's total length, but no more than 6' to 8' (arboreal)

Chelonian (turtles and tortoises) enclosures are based on their carapace length (CL). The minimum enclosure size differs depending on what kind of a chelonian it is.

Aquatic/Semi-Aquatic Turtles:

• Length: 4 to 5 times the aquatic turtle's CL
• Depth: 2 to 3 times the aquatic turtle's CL
• Height: 1-1/2 to 2 times the aquatic turtle's CL plus an additional 8" to 12"

Terrestrial Turtles and Tortoises:

• Length: 5 times the terrestrial turtle or tortoise's CL
• Depth: 3 times the terrestrial turtle or tortoise's CL
• Height: 1-1/2 to 2 times the terrestrial turtle or tortoise's CL

The minimum enclosure size for amphibians varies widely depending on how big the amphibian is and how many you are housing together. Some are tree dwellers that need tall enclosures while others spend most of their time in the water and can live in longer, lower tanks. Generally amphibians, either singly or in groups, require a 15- to 20-gallon tank, but you will need to research your specific species to determine the exact minimum size requirements.

It's important to note that these are just general requirements. Herps that are more active will need a larger cage than the minimum size to allow them plenty of living room.

You should also consider what kind of setup you're going to use. The above measurements are for simple enclosures. If you plan on using a naturalistic terrarium setup, the enclosure will need to be larger. At least 30% to 40% of the floor space will need to be open. Likewise, if you house more than one lizard, snake, or chelonian, the enclosure will need to be larger, sometimes significantly.

We Recommend
Exo-Terra Glass Terrariums	Zoo Med Repti Sand