How seconds and years are converted
A day is 86,400 seconds. Multiply that by the chosen year length to get the seconds in one year.
years = seconds ÷ (year length in days × 86,400)
- Choose the year length. The default Gregorian average is 365.2425 days, or 31,556,952 seconds.
- Divide seconds by the seconds in that year. For the reverse direction, multiply years by that same number.
- Take out whole years using the selected length, then whole days, hours and minutes. The remainder is seconds.
- Years are shown to up to 6 significant figures. Small durations stay visible as plain decimal years rather than rounding to zero.
Worked example: 1,000,000,000 seconds ÷ 31,556,952 = 31.6887 average Gregorian years. Using 365-day common years gives 31.7098 years.
Seconds and years compared
| Seconds | Average Gregorian years |
|---|---|
| 1,000,000 s | 0.0316887 years |
| 10,000,000 s | 0.316887 years |
| 100,000,000 s | 3.16887 years |
| 1,000,000,000 s | 31.6887 years |
| 1,000,000,000,000 s | 31,688.7 years |
| 31,556,952 s | 1 years |
| 315,569,520 s | 10 years |
| 3,155,695,200 s | 100 years |
Swipe the table sideways to see the rest.
These rows use the average Gregorian year of 365.2425 days, regardless of the selection above.
Things to consider
- Use the average Gregorian year for a general comparison across many years.
- Choose a common or leap year when comparing against one known year's length.
- The leftover days follow whole years of the selected length. An average year includes a fractional day.
- For a birthday-based age, use the Age Calculator rather than treating every calendar year as the same length.
Frequently asked questions
How many seconds are in a year?
An average Gregorian year has 31,556,952 seconds. A common year of 365 days has 31,536,000 seconds and a leap year of 366 days has 31,622,400 seconds. A Julian year, used in astronomy, is exactly 365.25 days or 31,557,600 seconds; it is not the Gregorian average.
How long is a billion seconds?
About 31.7 years. More precisely, it is 31.6887 average Gregorian years or 31.7098 common years.
Why do year lengths differ?
Calendar years contain either 365 or 366 days because of leap years. The Gregorian calendar has 97 leap years in each 400-year cycle, giving an average of 365.2425 days. That average is useful for durations, but does not describe the length of every individual year.
How many seconds are in a day?
For this conversion, one day is 24 × 60 × 60 = 86,400 seconds. One million seconds is 11.5741 days.
How old am I in seconds?
For a rough estimate, multiply your age in years by 31,556,952. For a date-based estimate, use the Age Calculator to count days from your birth date, then multiply those days by 86,400. Exact seconds also depend on your birth time and time zone.
Results are estimates for general information only, not financial, medical or professional advice.