It's about as heavy as a Brick
(Standard, traditional face brick - 1,900 cu. cm (120 cu. in))
A standard, traditional face brick weighs an average of 6.40 pounds. The steeple of the Church of St. Martin in Landshut, Germany is said to be the tallest brick tower in the world at a height of 130.6 m (428.5 ft) and was constructed using an estimated 650,000 bricks.
It's about one-and-three-tenths times as heavy as a Chihuahua
In other words, 6.40 pounds is 1.290 times the weight of a Chihuahua, and the weight of a Chihuahua is 0.7750 times that amount.(a.k.a. Chihuahue(o) (FCI standard)
The F&d&ration Cynologique Internationale (FCI) calls for Chihuahuas to weigh about 4.960 pounds. Relative to their body sizes, Chihuahuas have the largest brain size of any dog breed.
It's about three-fifths as heavy as a Gallon of Paint
It's about three-fifths as heavy as a Cat
It's about two times as heavy as a Human Brain
In other words, 6.40 pounds is 2.150 times the weight of a Human Brain, and the weight of a Human Brain is 0.4650 times that amount.(adult)
The average weight of an adult human brain is between 2.980 pounds. In humans and primates, sight and vision utilize about 30 different parts of the brain which together account for about half of the brain's size.
It's about two-fifths as heavy as a Bowling Ball
In other words, 6.40 pounds is 0.4266666670 times the weight of a Bowling Ball, and the weight of a Bowling Ball is 2.343750 times that amount.(most common selection among male bowlers)
With an allowable range of 6 lbs to 16 lbs, the most-preferred bowling ball weight among adult, male bowlers is 15 lbs. Because regulation balls measure the same diameter irrespective of their weight, ball density varies by size and balls weighing less than about 11.0231131 pounds will float in water.
It's about three times as heavy as a liter of Water
In other words, 6.40 pounds is 2.902910 times the weight of a liter of Water, and the weight of a liter of Water is 0.34448190 times that amount.(fresh; 4° C / 39.2° F; maximum density)
Contrary to popular belief, 1 liter (0.0.264172052358148 gal) of water at 4° C / 39.2° F (its point of maximum density) weighs 2.2046840 pounds rather than 1 kg exactly. The total volume of water on the planet Earth is about 13,590,000,000,000,000,000 (13.59 quntillion) L (3,590,000,000,000,000,000 gallons).