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Tarantula Enclosure Size Based on Leg Span Calculator: The Ultimate Guide to Spider Husbandry
Welcome to the most accurate tarantula enclosure size based on leg span calculator USA and global keepers rely on.
Whether you are bringing home your very first sling (spiderling) or you are upgrading a massive fully grown Theraphosa blondi getting your tarantula tank setup exactly right is the most critical step in exotic pet husbandry.
Many beginners make the mistake of buying standard glass aquariums without realizing that a tarantula's spatial needs are vastly different from a reptile or a fish.
A habitat that is too tall for a heavy bodied species can result in a fatal fall while an enclosure with insufficient dirt depth can stress a burrowing species to the point of illness.
By using our calculator above you take the guesswork out of sizing. Instead of relying on an inaccurate tarantula size chart by age this tool uses your spider's exact Diagonal Leg Span (DLS) and its specific lifestyle (terrestrial, arboreal or fossorial) to calculate the precise footprint, height and substrate depth required for a thriving, healthy spider.
Below we will break down exactly how to determine your tarantula tank size, the differences between species requirements and answer the most common questions about housing your eight-legged companion.
Why Diagonal Leg Span (DLS) is the Golden Standard
If you search the web for a tarantula size chart by age, you will quickly find that the information is wildly inconsistent.
This is because a tarantula's growth rate is not strictly tied to time. Instead their growth depends heavily on variables like the ambient temperature of their room, the frequency of their feeding the size of their prey and their specific genus.
Two spiders of the exact same age from the exact same egg sac can be completely different sizes a year later if one is kept slightly warmer and fed more often.
Because of this, age is a useless metric for choosing tarantula enclosures. The only accurate metric is the Diagonal Leg Span (DLS).
What is the leg span of a tarantula? The DLS is measured from the tip of the front right leg to the tip of the back left leg (or front left to back right) when the spider is resting in a natural, stretched-out position.
You do not need to physically touch the spider with a ruler simply hold a tape measure hovering safely above them or measure the shed exoskeleton after a molt.
Once you have this number in inches or centimeters our calculator applies the 3x Rule (providing a footprint that is at least three times the spider's DLS in length and width) to generate the perfect habitat dimensions.
Terrestrial, Arboreal and Fossorial: Tailoring the Habitat
Not all tarantulas navigate the world the same way. When planning your tarantula tank setup, you must categorize your spider into one of three lifestyles:
1. Terrestrial (Ground Dwelling) Species like the Mexican Redknee (Brachypelma hamorii) or the Curly Hair (Tliltocatl albopilosus) spend their lives walking on the forest floor.
For these heavy bodied spiders, floor space is paramount. More importantly terrestrial spiders are prone to climbing the glass walls of their enclosures.
If they fall from too high their heavy abdomens can easily rupture which is almost always fatal.
Our calculator specifically determines a Max Safe Fall Clearance to ensure the distance from the top of the dirt to the enclosure lid is no more than 1.5 times the spider's DLS.
2. Arboreal (Tree-Dwelling) Species like the Pink Toe (Avicularia avicularia) or the Greenbottle Blue (Chromatopelma cyaneopubescens - semi-arboreal) need vertical space to build intricate web tubes and climb.
The ideal arboreal tarantula enclosure size requires less floor footprint but significantly more height usually 3 to 4 times the spider's DLS. These setups require vertical cork bark tubes, fake foliage high up in the canopy and exceptional cross-ventilation to prevent stagnant air.
3. Fossorial (Burrowing) Species like the Cobalt Blue (Cyriopagopus lividus) or the OBT (Cyriopagopus minax) are nature's excavators. For a fossorial setup the actual cubic volume of empty air matters very little; the depth of the dirt is everything.
The calculator will recommend a substrate depth of at least 3 times the spider's DLS, allowing them to construct the deep, dark and secure tunnel systems they require to feel safe and hunt naturally.
Enclosure Aesthetics and Quality Brands
Once you know your dimensions it is time to choose the actual container.
While budget friendly options like modified plastic storage bins or clear acrylic shoeboxes work perfectly fine (provided you drill adequate ventilation holes), many hobbyists prefer premium display enclosures.
Brands like Tarantula Cribs have become incredibly popular because they offer crystal clear acrylic enclosures with pre-drilled cross ventilation and magnetic locking lids.
These premium options are specifically designed with tarantula escape artists in mind, ensuring your pet is secure while giving you a museum quality display.
Frequently Asked Questions (FAQs)
How big should a tarantula's enclosure be?
The general rule of thumb in the tarantula hobby is that an enclosure's length and width should be at least three times the spider's Diagonal Leg Span (DLS).
The height requirements vary drastically depending on whether the spider is arboreal (needs high vertical space) or terrestrial (needs shallow vertical space to prevent fall injuries).
Can a tarantula enclosure be too big?
Yes absolutely. While it might seem generous to give a small spider a massive mansion, can a tarantula enclosure be too big is a frequent concern for a reason. If an enclosure is too large, a tarantula may struggle to find its prey leading to starvation.
Additionally too much wide open space can cause immense stress to a spider making them defensive, skittish and prone to hiding constantly. It is always better to graduate your spider through appropriately sized enclosures as they molt and grow.
What size enclosure for 2 inch tarantula?
Using the 3x rule, a 2-inch tarantula requires an enclosure that offers a floor space of roughly 6x6 inches.
A common terrestrial juvenile setup for a spider this size would be a small clear acrylic box or a heavily modified deli cup measuring around 6 inches long, 6 inches wide and 4 to 5 inches tall (filled halfway with substrate).
Can a tarantula live in a 10 gallon tank?
Yes, a 10-gallon aquarium (which typically measures 20" L x 10" W x 12" H) can be an excellent permanent home for a fully grown adult terrestrial tarantula with a leg span of 5 to 6 inches.
However you must modify the tank by replacing the standard mesh screen lid with drilled acrylic or polycarbonate as tarantula claws can get easily stuck in wire mesh, leading to lost limbs.
You will also need to fill the tank with at least 5 to 6 inches of substrate to minimize the fall risk.
Is a 20 gallon tank too big for a tarantula?
For 95% of tarantula species a 20 gallon tank is far too large. Even for an adult, a 20-gallon tank provides too much empty space making it difficult for the spider to hunt and feel secure.
The only exceptions are the absolute giants of the tarantula world, such as a fully mature female Goliath Birdeater (Theraphosa blondi) or a Burgundy Goliath Birdeater (Theraphosa stirmi) which can reach leg spans of 10 to 11 inches and require the sprawling floor space a 20 gallon long tank provides.
