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Tarantula Enclosure Size Calculator — DLS (Diagonal Leg Span) Rule

Calculate the correct enclosure dimensions by DLS (diagonal leg span) and species type: terrestrial, arboreal, or fossorial. Proper sizing prevents falls (lethal for terrestrial species) and supports natural burrowing / climbing behavior.

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Minimum enclosure
15″ × 10″ × 5″
For terrestrial 5″ DLS tarantula
Arboreal species need vertical orientation + cork bark. Fossorial need 6+ inches substrate for burrowing. Terrestrial: wider floor + cross-ventilation. Air holes via fine mesh (no wire).

How to use the tarantula enclosure calculator

  1. Identify species orientation — Terrestrial, arboreal, or fossorial — determines enclosure shape.
  2. Measure DLS — Diagonal leg span; use ruler or photograph from above.
  3. Apply DLS multipliers — Terrestrial 3×2×1; arboreal 2×2×3; fossorial 3×2×1 + deep substrate.
  4. Check ventilation — Cross-ventilation for arboreal; minimal for terrestrial to retain humidity.

Enclosure design by tarantula orientation

Tarantulas divide into three behavioral categories based on their natural habitat, each requiring a different enclosure shape:

  • Terrestrial: Ground-dwelling species that spend their lives on substrate surface. Examples: Mexican red knee (Brachypelma hamorii), Chilean rose (Grammostola rosea), curly hair (Tliltocatl albopilosus). Need wide, shallow enclosures. Tall enclosures are dangerous — terrestrial tarantulas will climb and fall, often fatally rupturing the abdomen.
  • Arboreal:Tree-dwelling species that live in vertical silk “tubes” on bark or branches. Examples: pink toe (Avicularia avicularia), Trinidad chevron (Psalmopoeus cambridgei), most Poecilotheria species. Need tall enclosures with vertical cork bark, plants, and anchor points. Wide shallow enclosures produce stressed spiders that refuse to eat.
  • Fossorial: Burrowing species that spend most of their life underground. Examples: Mexican red rump (Tliltocatl vagans), golden baboon (Pterinochilus murinus), most Cyriopagopus. Need standard terrestrial floor plan plus 6+ inches of substrate depth for burrow construction. Often not visible for weeks at a time — this is normal, not a husbandry failure.

Enclosure sizing table by species category

DLSTerrestrial (L × W × H)Arboreal (L × W × H)
2 in sling6 × 4 × 3 in (deli cup)4 × 4 × 6 in (jar)
3 in juvenile9 × 6 × 3 in6 × 6 × 9 in
5 in adult15 × 10 × 5 in10 × 10 × 15 in
7 in adult21 × 14 × 7 in14 × 14 × 21 in
9 in adult (large species)27 × 18 × 9 in18 × 18 × 27 in

Frequently Asked Questions

What size enclosure does a tarantula need?

Terrestrial species (Brachypelma, Grammostola): 3× DLS length × 2× DLS width × 1× DLS height (e.g., a 5-inch DLS rose hair needs 15 × 10 × 5 in). Arboreal species (Avicularia, Psalmopoeus): 2× DLS length × 2× DLS width × 3× DLS height (vertical). Fossorial (burrowing) species (Brachypelma hamorii, Aphonopelma): same as terrestrial but with 6+ inches substrate depth for burrowing.

What is DLS in tarantula keeping?

DLS = Diagonal Leg Span — measured from the tip of the front-most leg to the tip of the opposite back leg (diagonally across the body). This is the standard tarantula sizing measurement because body length alone doesn't reflect how much space the animal needs. An adult female rose hair with 5-inch DLS has a body length of maybe 2 inches but occupies enclosure space based on DLS.

Can my tarantula fall and be injured?

Yes — especially arboreal species and juvenile terrestrials. A fall from 2+ DLS height can rupture the abdomen and kill the spider within hours. This is why terrestrial enclosures use 1× DLS height maximum: low fall risk. Arboreal species have hardened exoskeletons and better climbing reflexes, but still benefit from cork bark and plants to break falls. Always monitor new acquisitions for climbing behavior that suggests wrong enclosure orientation.

How often do tarantulas need to eat?

Slings (spiderlings) and juveniles: 1–2 pre-killed prey items weekly. Adult females: 2–4 prey items every 2–3 weeks. Adult males: less frequent (they often stop eating near maturity). Prey should be 1/2 to 1× the body length — crickets, dubia roaches, mealworms, superworms. Tarantulas refuse food during molting (pre-molt is the most common reason for sudden food refusal); remove uneaten prey within 24 hours.

How long do tarantulas live?

Enormously species- and sex-dependent. New World terrestrials (Brachypelma, Grammostola): females 20–30+ years, males only 5–8 years. Old World species (Poecilotheria, Ceratogyrus): females 10–15 years, males 3–5 years. Tree-dwelling Avicularia: females 10–12 years, males 4–5 years. Buying an adult female of any species is a 15–25 year commitment.

Are tarantulas dangerous / venomous?

All tarantulas are venomous but vary dramatically in potency. New World species (most beginner species) have mild venom comparable to a bee sting — no medical emergency in healthy adults. Old World species (Poecilotheria, Pterinochilus, Heteroscodra) have significantly more potent venom that can cause intense pain, muscle cramps, sweating, and hospital visits. New World species also have urticating hairs (skin/eye irritation); Old World species do not but are faster and more defensive. Beginners should stick to New World terrestrial species.

Sources & References

  1. [1]
  2. [2]
    Tom's Big Spiders Care Guides — Tom's Big Spiders
  3. [3]
    Tarantula Husbandry — Merck Veterinary Manual
  4. [4]
    The Tarantula Keeper's Guide (Schultz) — Schultz & Schultz 2009