Enclosure Size Guide

Size off diagonal leg span (DLS) — leg tip to opposite leg tip — not body length, and not the species name alone. The working rule most keepers use:

• Ground dwellers (terrestrial): floor about 3× DLS long by 2× DLS wide, kept low.
• Climbers (arboreal): height about 3× DLS, with vertical bark to climb.
• Burrowers (fossorial): substrate depth is the priority — 2–3× DLS deep.

Use the finder above — it does the math and adjusts for your spider's current age.

This is the single most important thing to get right, because it flips the whole enclosure shape. Quick guide:

• Terrestrial — walks on the ground, may dig a shallow scrape. Most beginner species (Grammostola, Brachypelma, Aphonopelma, Tliltocatl).
• Arboreal — long-legged, fast, builds silk tubes up high on bark or plants (Avicularia, Caribena, Psalmopoeus, Poecilotheria).
• Fossorial — spends most of its life in a deep burrow and rarely sits out (Cyriopagopus lividus, Pelinobius, Hysterocrates).

If your species is in the dropdown above, we've already classified it for you.

Because a fall can kill them. Terrestrial species are heavy-bodied, and the abdomen is essentially a thin-walled sac. A drop from the top of a tall enclosure onto hard substrate can rupture the abdomen, which is usually fatal.

That's why for ground dwellers we cap the space from substrate to lid at roughly 1.5× DLS. Height isn't "more room" for a terrestrial — it's a hazard. Arboreal species are built to climb and grip, so the same height is a feature for them, not a risk.

No — and this is a common, costly mistake. A spiderling in a large enclosure struggles to find its food (prey escapes and can even harass a molting sling), the space is far harder to keep humid at that scale, and you lose eyes-on with a tiny animal that can burrow and vanish.

Slings go in small containers sized close to them, then get rehoused up in stages. It's a feature of the hobby, not a failure of planning.

There's no calendar for it — it's driven by molts, and molt frequency depends on species and how much you feed. Rough pattern: slings may need an upgrade every few molts as they roughly double in size; juveniles less often; a mature adult can stay in its final enclosure for years.

The trigger to watch: the footprint is getting close to the spider's leg span, or it can no longer turn around and web comfortably. That's the signal to size up.

Depends on lifestyle. Terrestrial: a few inches so they can dig a scrape — and for these, deeper substrate is also your fall-safety tool, since it raises the floor and shrinks the drop to the lid. Fossorial: deep is the whole point — aim for 2–3× DLS so they can build a proper burrow. Arboreal: substrate is mostly for humidity and a water dish; a modest layer is fine since the action happens on the bark above.

Fewer numbers than old care sheets suggest. Chasing a specific humidity percentage with a hygrometer is largely outdated advice — it led a lot of keepers to seal enclosures shut and cause stagnant, moldy conditions that kill spiders faster than dryness does.

The current consensus is to manage conditions, not a readout: give good cross-ventilation, keep a water dish (this alone covers most species), and set substrate moisture to the animal's origin — damp for tropical species, dry for arid ones like Aphonopelma. Get those three right and humidity takes care of itself.

Usually no. If you're comfortable in your home (roughly 68–78°F / 20–26°C), most commonly kept species are fine at room temperature. Tarantulas don't bask — heat just speeds up metabolism, and warmth pulls moisture out of the enclosure.

If your room genuinely runs cold, warm the ambient air of the space rather than sticking a mat to the enclosure. Side- or bottom-mounted mats can create a hot spot the spider can't escape and can dry it out or overheat it.

Both work; the trade-offs are practical. Acrylic is lighter, holds humidity well, and is clearer for viewing slings — but scratches more easily. Glass is scratch-resistant and heavier so it's stable. What matters more than material is that the enclosure has the right orientation for the lifestyle and cross-ventilation (vents on opposite sides, or side plus top), rather than a single vent that lets air go stale.

As a rule, no. Tarantulas are solitary and cannibalistic — cohousing usually ends with one spider eating the other. One enclosure, one spider is the safe default.

There are a few genuinely communal-capable species (Monocentropus balfouri is the usual example) that experienced keepers keep in groups, but that's an advanced setup with its own rules, not a space-saving shortcut for beginners.

Four things cover nearly every terrestrial/fossorial setup: a correctly sized & oriented enclosure, substrate at the right depth, a water dish, and a hide (cork bark or half a flowerpot). Arboreal species swap the emphasis to a tall vertical piece of cork bark to anchor webbing. Skip the plastic plants and gimmicks until the basics are dialed in.