Seconds to Years
Type a value in either box to convert between seconds and years. The factor is 3.16881e-08.
| Seconds | Years |
|---|---|
| 1 s | 3.16881e-08 yr |
| 2 s | 6.33762e-08 yr |
| 3 s | 9.50643e-08 yr |
| 5 s | 1.5844e-07 yr |
| 10 s | 3.16881e-07 yr |
| 25 s | 7.92202e-07 yr |
| 50 s | 1.5844e-06 yr |
| 100 s | 3.16881e-06 yr |
How to use
- Enter a value in the Seconds field.
- The Years figure appears immediately — no button to press.
- Typing in the Years field converts back to Seconds the same way.
- Use the reference table for the values that come up most often.
Seconds to Years formula
To convert seconds to years, multiply by 3.16880878e-08.
yr = s × 3.16880878e-08
Why this factor: the second and the year are both defined against the second, so dividing one definition by the other gives 3.16880878e-08 directly. Both definitions are set out in full below.
To go the other way, divide by 3.16880878e-08 — or use the Years to Seconds converter, which is the same calculation reversed.
Worked example
Start with 365 s. Multiply by 3.16880878e-08 to get 1.15662e-05 yr.
365 s × 3.16880878e-08 = 1.15662e-05 yr
The converter above does this for any value you type, in either direction.
What is a second?
The second is the SI base unit of time and the most precisely realized unit in all of measurement.
Definition: Defined by fixing the caesium-133 hyperfine transition frequency at exactly 9,192,631,770 hertz — the basis of every atomic clock.
Where it is used: Universal, and the reference for all other time units.
What is a year?
A year here means the Julian year, the fixed-length year used for scientific and financial arithmetic.
Definition: Exactly 365.25 days, so exactly 31,557,600 seconds.
Where it is used: Astronomy (the light-year is built on it), interest and depreciation calculations, and age arithmetic.
Worth knowing: The Gregorian calendar year averages 365.2425 days, so the two diverge by about 11 minutes per year.
Seconds vs Years
The second is an SI unit while the year is a specialized unit. That is why the factor between them is not a round number: the two systems were defined independently and only later tied together by exact agreement.
Frequently asked questions
How many years are in a second?
One second equals 3.16880878e-08 years.
What is the formula to convert seconds to years?
Multiply the number of seconds by 3.16880878e-08. To reverse it, divide by 3.16880878e-08 instead.
How do I convert years back to seconds?
Divide by 3.16880878e-08, which is the same as multiplying by 31557600.
How many years are in 10 seconds?
10 s works out to 3.16881e-07 yr.
Is there anything to watch out for with years?
The Gregorian calendar year averages 365.2425 days, so the two diverge by about 11 minutes per year.
How is the second defined?
Defined by fixing the caesium-133 hyperfine transition frequency at exactly 9,192,631,770 hertz — the basis of every atomic clock.