Aeons to Years (Gyr to yr)

1 aeon equals 1,000,000,000 years exactly.

1 aeon = 1,000,000,000 years

How to convert aeons to years

To convert aeons to years, multiply the number of aeons by 1,000,000,000. This factor is exact. To go the other way, multiply years by 1×10⁻⁹.

years = aeons × 1,000,000,000

Example: 10 aeons = 10,000,000,000 years.

Months and years are not constant. This site uses the average Gregorian year of 365.2425 days, so one 'year' converts to 365.2425 days, not 365; use 'common year' for exactly 365 days.

About these units

Aeon (Gyr)

AstronomicalCurrent unit

One billion years. The Earth is about 4.5 aeons old.

Aeon comes from a Greek word meaning life, vital force, or an age, and its Latin cousin aevum lies behind English words such as eternal and medieval. In ordinary speech it means any very long, indefinite stretch. Philosophical and religious traditions use it differently, with Buddhist and Hindu texts sometimes rendering kalpa as aeon and Gnostic writers using it for divine emanations.

Astronomers fix a definite size, defining an aeon as a billion years. The figure used here is therefore 10 to the power of 9 Gregorian years, about 3.16 times 10 to the power of 16 seconds, which is a convention rather than a measured length. Geologists use the closely related spelling eon for the largest divisions of Earth's history, namely the Hadean, Archean, Proterozoic and Phanerozoic, and these are not billion-year blocks, since the Phanerozoic covers only about 538.8 million years. With Earth about 4.54 billion years old, it is roughly 4.5 aeons old.

1 aeon = 3.1556952×10¹⁶ seconds (exactly).

Sources: Wikipedia: Aeon; Wikipedia: Geologic time scale

Year (yr)

CalendarCurrent unit

The average Gregorian calendar year of 365.2425 days (31,556,952 seconds). A common year has 365 days and a leap year 366.

A year is the Earth's trip around the Sun, but there are several versions. The tropical year, which tracks the seasons, is about 365.2422 days. The sidereal year, measured against the stars, is about 365.2564 days, roughly 20 minutes longer, because the Earth's axis precesses. Calendars must squeeze these into whole days, which is the origin of leap years. English year descends from Old English gear, while Latin annus, the source of annual, comes from a different root.

The Gregorian calendar, introduced by Pope Gregory XIII's bull of 24 February 1582, fixed the problem of Julian drift that had moved the March equinox away from 21 March and upset the date of Easter. Ten days were skipped, so Thursday 4 October was followed by Friday 15 October. Its rule of skipping leap days in century years not divisible by 400 gives a mean year of 365.2425 days, the value this site uses for the year. Britain and its empire switched in 1752 and Russia in 1918. Scientists write the year as a, with the Julian year fixed at 31,557,600 seconds.

1 year = 31,556,952 seconds (exactly).

Sources: Wikipedia: Year; Wikipedia: Gregorian calendar

Related conversions

See all time units.