13.8 billion years
13.8 GyrTime · definition
Time conversions use a Julian year of exactly 365.25 days.
Time
Just how long is 13.8 billion years?
A duration of 13.8 billion years is 4.354949 × 10¹⁷ seconds.
Deep time
13.8 Gyr
ELAPSED TIME
13.8 billion years
Time conversions use a Julian year of exactly 365.25 days.
13.8 GyrTime
0
Observable universe
The observable universe is the region from which light or other signals have had time to reach us since the early universe.
13.8 GyrAge
0
Both timelines start together. Length measures elapsed time, not a physical distance.
A little perspective
13.8 billion years is approximately equal to the age of the observable universe.
Measurements, assumptions & sources +
13.8 billion years
Time: 13.8 Gyr; definition.
Time conversions use a Julian year of exactly 365.25 days.
Observable universe
Age: 13.8 Gyr; cosmological estimate.
About 92 billion light-years across in present-day comoving distance. Space expanded while the light travelled. The 13.8-billion-year age is a time, not its radius divided by light speed. The total universe may be far larger, possibly infinite.
The marked age is calibrated. Unmeasured illustration details are representative.
Measurement details
Why these numbers?
Compare 13.8 billion years with the age of the observable universe. The notes below explain how each value was chosen.
Observable universe
13.8 GyrAge · cosmological estimate
About 92 billion light-years across in present-day comoving distance. Space expanded while the light travelled. The 13.8-billion-year age is a time, not its radius divided by light speed. The total universe may be far larger, possibly infinite.
- Comparing
- Time ↔ Age
- Relative size
- 13.8 billion years is approximately equal to the age of the observable universe.
How to read the visual
The diagram uses the recorded measurements. Details outside the marked spans do not set the scale.
- The age of the observable universe: The measurement is labelled cosmological estimate. Check the source notes for its basis.
A duration is an interval, not a calendar date.
4.3549 × 10¹⁷ sseconds
1.2097 × 10¹⁴ hhours
5.0405 × 10¹² daysdays
1.38 × 10¹⁰ yearsyears
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