Days to Years Converter

What this converter does

This turns a number of days into years. Since a year is not a whole number of days, it works on an average year, which makes the result a close estimate rather than an exact count. It is handy for seeing how many years a large day count comes to. Enter the days and the years come straight back.

How to use it

1. Enter Days. Type the number of days.

Press Calculate and the equivalent in years appears.

The 365.25-day year

The conversion divides by 365.25, the average length of a year in days. A common year is 365 days, but every four years a leap day is added to keep the calendar in step with the seasons, and spreading that extra day across four years adds a quarter of a day to each on average. So 365.25 days is the average year once leap years are counted in, which is why it is used here instead of a flat 365.

Why it is an estimate

Because it uses an average, the answer is close rather than exact for any particular span. No single year is 365.25 days long, so a stretch with more or fewer leap years than average will come out a little different. You can even see the averaging at work: a plain 365-day year comes back as about 0.999 of a year here, just shy of 1, because it is being measured against the slightly longer average. For everyday purposes that is fine, but for the exact number of years between two real dates, a date-to-date tool that counts actual days is the better choice.

An example

Take 365.25 days. Divide by 365.25 and you get exactly 1 year. A span of 730.5 days is 2 years, and 1,000 days is about 2.74 years. A plain 365 days comes out as roughly 0.999 of a year, a hair under one, which is the leap-year averaging showing through.

Questions people ask

How many days are in a year?

365 in a common year and 366 in a leap year, which average to 365.25. This converter uses that 365.25 average.

Why 365.25 and not 365?

Because of leap years. Adding a leap day every four years works out to an extra quarter day per year on average, giving an average year of 365.25 days.

How many years is 1,000 days?

About 2.74 years, since 1,000 divided by 365.25 is roughly two and three quarters.

How do I go from years back to days?

Multiply the years by 365.25, or use a years-to-days converter, which uses the same average year.

References

1. U.S. Naval Observatory, Astronomical Applications Department: Leap Years. https://aa.usno.navy.mil/faq/leap_years