Adult otters range from about 2 feet to nearly 6 feet long (including the tail), depending on the species, and can weigh anywhere from roughly 2 pounds up to about 100 pounds. The smallest otters are about house-cat sized, while the largest are closer to a medium-sized dog in weight and length.

Typical otter sizes

  • Most otter species fall in the 0.6 to 1.8 meter (2 to 5.9 foot) length range, with weights from about 1 to 45 kilograms (2.2 to 99 pounds).
  • A common example, the North American river otter, usually reaches about 3 to 4 feet (0.9 to 1.2 meters) long and 11 to 30 pounds (5 to 14 kilograms).
  • Adult river otters in general are often in the 2.5 to 5 foot (76 to 152 centimeter) range and 10 to 33 pounds (4.5 to 15 kilograms).

Smallest vs. biggest otters

  • The Asian small-clawed otter is the smallest species, at about 65 to 94 centimeters (26 to 37 inches) long and only 1 to 5 kilograms (2.2 to 11 pounds).
  • At the other extreme, the giant otter of South America averages 145 to 180 centimeters (57 to 71 inches) long, with some records up to 240 centimeters (94 inches) and males weighing around 26 to 34 kilograms (57 to 75 pounds).
  • Sea otters are among the heaviest, with males typically 22 to 45 kilograms (49 to 99 pounds) and 1.2 to 1.5 meters (47 to 59 inches) long.

Sea otter size details

  • Male Alaska sea otters can reach about 148 centimeters (58 inches) and typically weigh 27 to 39 kilograms (60 to 85 pounds), with some large males approaching 45 kilograms (100 pounds).
  • Females are smaller, up to about 140 centimeters (55 inches) and 16 to 27 kilograms (35 to 60 pounds).
  • California sea otter males average around 122 centimeters (about 4 feet) and 29 kilograms (64 pounds), while females average roughly 20 kilograms (44 pounds).

Handy size snapshot (HTML table)

[9] [9] [1] [1] [5] [5] [6][1] [6][1] [3] [3]
Otter type Typical length Typical weight
General otter range 0.6–1.8 m (2–5.9 ft)1–45 kg (2.2–99 lb)
Asian small-clawed 65–94 cm (26–37 in)1–5 kg (2.2–11 lb)
North American river otter 0.9–1.2 m (3–4 ft)5–14 kg (11–30 lb)
Giant otter 1.45–1.8 m (57–71 in), up to 2.4 m~22–34 kg (49–75 lb)
Sea otter (male) 1.2–1.5 m (47–59 in)22–45 kg (49–99 lb)
Information gathered from public forums or data available on the internet and portrayed here.