1,000,000,000 ("one billion" on the short scale; "one milliard" on the long scale; one thousand million) is the natural number following 999,999,999 and preceding 1,000,000,001. With a number, "billion" can be abbreviated as b, bil or bn.
In standard form, it is written as 1 × 109. The metric prefixgiga indicates 1,000,000,000 times the base unit. Its symbol is G.
One billion years may be called an eon in astronomy or geology.
Previously in British English (but not in American English), the word "billion" referred exclusively to a million millions (1,000,000,000,000). However, this is not common anymore, and the word has been used to mean one thousand million (1,000,000,000) for several decades.
The term milliard could also be used to refer to 1,000,000,000; whereas "milliard" is rarely used in English, variations on this name often appear in other languages.
It is a common metric used in macroeconomics when describing national economies.
Sense of scale
Visualization of powers of ten from one to 1 billion
The facts below give a sense of how large 1,000,000,000 (109) is, according to current scientific evidence:
Time
109 seconds (1 gigasecond) equal 11,574 days, 1 hour, 46 minutes and 40 seconds (approximately 31.7 years, or 31 years, 8 months, 8 days).
About 109 minutes ago, the Roman Empire was flourishing and Christianity was emerging. (109 minutes is roughly 1,901 years.)
About 109 hours ago, modern human beings and their ancestors were living in the Stone Age (more precisely, the Middle Paleolithic). (109 hours is roughly 114,080 years.)
About 109 days ago, Australopithecus, an ape-like creature related to an ancestor of modern humans, roamed the African savannas. (109 days is roughly 2.738 million years.)
About 109 months ago, dinosaurs walked the Earth during the late Cretaceous. (109 months is roughly 83.3 million years.)
A billion square inches could make a square about one half mile on a side.
A bolt of finely woven 1000-TC bed sheet linen with a billion thread crossings would have an area of 40 square metres (48sqyd), comparable to the floor area of a motel unit.
A billion grains of table salt or granulated sugar would occupy a volume of about 2.5 cubic feet (0.071m3).
A billion cubic inches would be a volume comparable to a large commercial building slightly larger than a typical supermarket.
Weight
Any object that weighs one billion kilograms (2.2×109lb) would weigh about as much as 5,525 empty Boeing 747-400s.
A cube of iron that weighs one billion pounds (450,000,000kg) would be 38.62 metres (126.7ft) on each side.
Products
As of July 2016, Apple has sold one billion iPhones. This makes the iPhone one of the most successful product lines in history, surpassing the PlayStation and the Rubik's Cube.
As of January 2025, Facebook has 3.065 billion users.
Nature
A small mountain, slightly larger than Stone Mountain in Georgia, United States, would weigh (have a mass of) a billion tons.
There are billions of worker ants in the largest ant colony in the world, which covers almost 4,000 miles (6,400km) of the Mediterranean coast.
A is a cube; B consists of 1000 cubes the size of cube A, C consists of 1000 cubes the size of cube B; and D consists of 1000 cubes the size of cube C. Thus there are 1 millionA-sized cubes in C; and 1,000,000,000 A-sized cubes in D.
