Seconds to Years Converter
Convert seconds to years — one year is 31,556,952 seconds on the Gregorian average. Results update as you type; exact factors shown.
One second is 3.1689e-8 year (365.2425 days) — see the exact factor, not a rounded rule of thumb.
How the seconds to years converter works
Time converts through the second. Minutes, hours, days and weeks are exact multiples. A month is taken as the Gregorian average (30.436875 days) and a year as the Gregorian average (365.2425 days = 31,556,952 s); calendar months and leap years vary from these averages.
The US uses customary units (US gallon, short ton, °F) in daily life; NIST SP 811 gives the exact SI factors.
Common time conversions
| From | To | Units |
|---|---|---|
| 86,400 s | 0.0027 yr | seconds to year (365.2425 days) |
| 604,800 s | 0.0192 yr | seconds to year (365.2425 days) |
| 1,000,000 s | 0.0317 yr | seconds to year (365.2425 days) |
| 2,629,746 s | 0.0833 yr | seconds to year (365.2425 days) |
| 10,000,000 s | 0.3169 yr | seconds to year (365.2425 days) |
| 31,536,000 s | 0.9993 yr | seconds to year (365.2425 days) |
| 31,556,952 s | 1 yr | seconds to year (365.2425 days) |
| 100,000,000 s | 3.1689 yr | seconds to year (365.2425 days) |
| 315,569,520 s | 10 yr | seconds to year (365.2425 days) |
| 1,000,000,000 s | 31.6887 yr | seconds to year (365.2425 days) |
| 3,155,695,200 s | 100 yr | seconds to year (365.2425 days) |
| 10,000,000,000 s | 316.8874 yr | seconds to year (365.2425 days) |
Units in this converter and their exact factors
| Unit | Symbol | One unit in seconds |
|---|---|---|
| millisecond | ms | 0.001 second |
| second | s | 1 second |
| minute | min | 60 second |
| hour | h | 3,600 second |
| day | d | 86,400 second |
| week | wk | 604,800 second |
| month (average, 30.4369 days) | mo | 2,629,746 second |
| year (365.2425 days) | yr | 31,556,952 second |
FAQFrequently asked questions about time conversion
How many seconds in a year?
31,556,952 on the Gregorian average; a common year of 365 days has 31,536,000.
What is a billion seconds in years?
31.69 years.
What is a million seconds?
About 11.6 days — far shorter than most people guess.
Why is a billion seconds so much longer than a million?
Because a billion is a thousand millions: 11.6 days becomes 31.7 years.
Is a year exactly 31.5 million seconds?
Close — 31,556,952, which is often approximated as pi times ten million (31,415,927), accurate to half a percent.
Where these figures come from
- BIPM — The International System of Units (SI Brochure, 9th edition) — definitions of the base and derived units.
- NIST Special Publication 811 — Guide for the Use of the International System of Units — the exact conversion factors used here.
- National Institute of Standards and Technology (NIST) — United States's national measurement authority.
Last checked: September 2026. Conversion factors are fixed by definition and do not change with tax years or regulations.