For most crabs, you’re steaming to heat through , not to cook from raw, so time depends on whether they’re whole or just legs, and if they’re raw, pre‑cooked, frozen, or thawed.

Quick Scoop (short answer)

  • Crab legs (pre‑cooked, thawed): 5–6 minutes over boiling water until hot and fragrant.
  • Crab legs (pre‑cooked, frozen): 10–12 minutes; they should be piping hot and steaming when cracked.
  • Whole blue crabs: about 15–30 minutes, depending on pot size and how many you stack; shells should turn fully bright red.
  • Whole large crabs (king/Dungeness, raw): about 15–25 minutes; finish when shell is uniformly red/orange and meat is opaque and firm, not jelly‑like.

Always start timing once the water is at a strong simmer/boil and producing steady steam, and use visual doneness cues (bright red shell, opaque meat, juices running clear) rather than the clock alone.

Typical steaming times by crab type

Crab legs (most common case)

  • Pre‑cooked, thawed legs:
    • 5–6 minutes in a steamer basket over boiling water.
* Good for snow crab and king crab legs that are already reddish (pre‑cooked).
  • Pre‑cooked, frozen legs:
    • 10–12 minutes; they need longer to heat through from frozen.
  • Signs they’re ready:
    • Strong crab aroma, shells very hot to the touch, meat steams when cracked, and pulls out easily from the shell.

Example: A cluster of thawed snow crab legs in a stovetop steamer usually hits perfect, juicy texture right around 6 minutes; beyond 10 minutes the meat starts to dry out and shred.

Whole crabs (blue, Dungeness, king)

  • Live/whole blue crabs:
    • Roughly 15–30 minutes depending on burner strength and how many crabs are stacked in the pot.
* Many home cooks report 15–20 minutes for a dozen in a strong steamer, longer if the pot is crowded.
  • Whole Dungeness or similar medium‑large crabs:
    • Around 12–20 minutes; some guides peg “perfectly cooked” at about 12 minutes once steaming vigorously, with up to ~20 minutes for big, heavy crabs.
  • Whole king crab (if actually raw, which is rare):
    • About 15–20 minutes; if it starts blue/green, steam until shell is fully red/orange and meat is opaque.
* Most king crab sold retail is already cooked; if the shell is already red, you’re just reheating and can use the 10–12‑minute “pre‑cooked legs” guideline.

Key doneness checks for whole crabs:

  • Shell is uniformly bright red or orange, no dark/greenish patches left.
  • Meat is opaque white (with some natural reddish/brown areas), firm but still moist.
  • No translucent or jelly‑like sections at the joints or body cavity.

Simple step‑by‑step (for safe, tasty results)

  1. Prep the pot
    • Add 1–2 inches of water, optionally with salt, aromatics, or vinegar/beer for flavor; set a rack or steamer basket above the water line.
 * Bring to a strong simmer/boil so you have constant steam before adding crab.
  1. Load the crab
    • Arrange crab in a single or gently layered stack so steam can circulate; don’t fully submerge it.
 * Cover tightly to trap steam.
  1. Steam by type
    • Legs, thawed: 5–6 minutes.
    • Legs, frozen or very thick: 10–12 minutes.
    • Whole crabs: 15–25 minutes depending on size and quantity, using the visual checks above.
  1. Rest and serve
    • Let crabs sit off heat, covered, for 2–3 minutes so heat evens out, then serve with butter, lemon, or seasoning.

Quick safety and quality tips

  • When in doubt, go by look and texture rather than adding lots of extra minutes; over‑steaming dries the meat and makes it stringy.
  • If the crab was sold fully cooked (red/orange shell), your goal is gentle reheating, not long cooking; stay on the shorter side of the ranges.
  • Always refrigerate leftovers promptly and reheat only once to keep quality and food safety on point.

If you tell me what kind of crab you have (blue, snow, king, Dungeness, whole vs legs, raw vs pre‑cooked), I can give you a very specific minute‑by‑minute timing for your exact situation.