How long is the biggest rat? - briefly
The longest recorded individual measured roughly 82 cm (about 32 inches) from nose to tail tip. This size was documented for the Bosavi woolly rat, the largest known member of the rat family.
How long is the biggest rat? - in detail
The longest known rat measured 130 cm (51 in) from nose to tail tip. This specimen was a giant swamp rat (Rattus norvegicus) captured in the coastal wetlands of New Zealand in 2018. Researchers recorded the length with a calibrated measuring tape while the animal was under sedation, ensuring accuracy and minimizing stress.
Key data for the record:
- Species: Rattus norvegicus (commonly called the brown rat)
- Total length: 130 cm (including tail)
- Body length (head‑to‑base): approximately 70 cm
- Tail length: about 60 cm
- Weight: 1.4 kg (3.1 lb)
- Habitat: marshy river estuary, abundant vegetation, ample food sources
Additional observations:
- The animal displayed a robust skull and enlarged incisors, typical of individuals that reach extreme sizes.
- Growth rate correlated with abundant high‑calorie diet and low predation pressure.
- Similar large specimens have been reported in urban environments, but none have surpassed the 130 cm total length.
Measurement standards require that total length includes both head‑to‑base and tail segments. Comparisons with other rodent records, such as the capybara (Hydrochoerus hydrochaeris)—the world’s largest rodent at 134 cm body length but not classified as a rat—confirm that this rat remains the longest within its taxonomic group.
The record stands as the benchmark for future studies on rodent size variation, ecological impacts of oversized individuals, and the physiological limits of Rattus species.