It's about one-third as heavy as an Anchor of a Cruise Ship
In other words, 4,000 kilograms is 0.354 times the weight of an Anchor of a Cruise Ship, and the weight of an Anchor of a Cruise Ship is 2.82 times that amount.(for QE2 forward anchor, a.k.a. RMS Queen Elizabeth 2)
Each of the forward anchors of the RMS Queen Elizabeth 2 weighs 11,300 kg. The anchor of the QE2 now sits in front of the Holyrood Church in Southampton, England, United Kingdom, along a pedestrian tourist route known as "the QE2 mile."
It's about six times as heavy as a Cow
In other words, 4,000 kilograms is 5.9 times the weight of a Cow, and the weight of a Cow is 0.17 times that amount.(for Holstein, a.k.a. Holstein Friesian, a.k.a. Friesian, Bos primigenius) (adult, heifer)
A mature Holstein cow (the well-known black-and-white, spotted breed of cow) typically weighs 680 kg. President William Howard Taft (1909 - 1913) kept a Holstein cow named Pauline Wayne on the White House grounds — a gift from a Wisconsin senator and the source of the First Family's milk.
It's about seven-and-a-half times as heavy as a Grizzly Bear
In other words, 4,000 kilograms is 7.68 times the weight of a Grizzly Bear, and the weight of a Grizzly Bear is 0.13 times that amount.(a.k.a. brown bear, a.k.a. silver bear, Ursus arctos horribilis) (Adult, male, coastal area population average)
An adult, male grizzly bear from a coastal area (where food is plentiful) can weigh up to 521 kg. In spite of their tremendous size, grizzly bears can run at speeds of up to 55 kph (34 mph).
It's about eight times as heavy as a Polar Bear
In other words, 4,000 kilograms is 7.75 times the weight of a Polar Bear, and the weight of a Polar Bear is 0.129 times that amount.(Ursus maritimus) (adult, male)
An adult, male polar bear weighs between 352 and 680 kg. Polar bears are so heavily insulated by their 9.9 cm (3.9 in) layer of blubber that they are often difficult to detect using infrared photography sensors.
It's about nine times as heavy as a Grand Piano
In other words, 4,000 kilograms is 8.9 times the weight of a Grand Piano, and the weight of a Grand Piano is 0.11 times that amount.(for Steinway & Sons, Model D Concert Grand Piano)
A Grand Piano, of the kind used for concert performances in large music halls, weighs 450 kg. Well-made pianos such as this may last 75 to 100 years.
It's about nine-and-a-half times as heavy as a Horse
In other words, 4,000 kilograms is 9.5 times the weight of a Horse, and the weight of a Horse is 0.11 times that amount.(Equus ferus caballus) (Arabian, adult)
n Arabian riding horse (or similar breed) weighs between 380 and 450 kg. During races, horses must carry jockeys and their equipment, which in the Kentucky Derby, for example, can weigh up to 54.4 kg.
It's about sixteen times as heavy as a Pig
In other words, 4,000 kilograms is 16 times the weight of a Pig, and the weight of a Pig is 0.06 times that amount.(Domestic pig, Sus scrofa domesticus, a.k.a. S. domesticus) (adult)
Domestic pigs weigh between 50 kg and 450 kg. The titular character "Babe the pig" in the 1995 family film was played by 48 different American Yorkshire piglets due to the length of filming and the rate at which piglets reach adulthood.