FORMICARIUM LOG — TARANTULA CALCULATOR

How much should your tarantula eat?

Prey size, number of crickets or roaches, feeding frequency and post-molt wait, calculated from species, leg span, temperature and abdomen size.

34 SPECIES + YOURSBrachypelma, Grammostola, Tliltocatl, Poecilotheria, Theraphosa…
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Name

Species

Leg span (cm)

Stage

Temperature (°C)

Measured from a front leg to the opposite back leg. Slings are often 1–3 cm.

Abdomen (seen from above)

Molt

Last molt date

Prey size: no bigger than the tarantula’s abdomen. Several small prey are better than one huge one.
Frequency: a sling (under 3 cm) eats once or twice a week, a juvenile every 1–2 weeks, an adult every 2–4 weeks.
Check the abdomen: if it is bigger than the head (carapace), it is not hungry. If it is smaller, feed it.
Molting: in premolt it refuses food, which is normal. After the molt, wait 3–5 days for a sling, 10–14 days for an adult.
Slow species (Grammostola, Brachypelma, Aphonopelma) can safely fast for months as long as the abdomen stays plump.

Leg span	Prey	Per meal	Frequency	After molt
2 cm	Pinhead crickets (3–5 mm)	1	every 5 days	wait 3 days
4 cm	Small crickets (6–9 mm)	1	every 6 days	wait 4 days
7 cm	Medium crickets (12–15 mm)	2	every 9 days	wait 6 days
10 cm	Large crickets (18–22 mm)	2	every 11 days	wait 8 days
14 cm	Adult crickets (25 mm)	3	every 14 days	wait 10 days
18 cm	Adult crickets (25 mm)	5	every 17 days	wait 13 days

These are average guidelines. Every tarantula is different: the abdomen matters more than the calendar.

Write to me: I add requested species and fix the amounts.