Days to Years Converter

About the d to yr calculation

One day is exactly 0.00273791 years, so converting between them is a single multiplication. Enter any value above and the result updates as you type. Twenty-four hours, or 86,400 seconds — one full rotation of the Earth relative to the Sun. The mean Gregorian year — 365.2425 days, which is why leap years exist.

Formula

yr = d × 0.00273791

1 d = 0.00273791 yr
1 yr = 365.243 d

Worked example

To convert 30 d, multiply by 0.00273791: 30 × 0.00273791 = 0.082137 yr.

Frequently asked questions

How many years are in a day?

There are 0.00273791 years in one day. To convert any amount, multiply the number of days by 0.00273791.

How do I convert years back to days?

Divide instead of multiplying, or equivalently multiply by 365.243. One year is 365.243 days.

Is this conversion exact?

For seconds through weeks, yes — they are fixed multiples. The year is the mean Gregorian year of 365.2425 days, which is an average rather than the length of any particular calendar year.

Where is each of these units used?

Days: twenty-four hours, or 86,400 seconds — one full rotation of the Earth relative to the Sun. Years: the mean Gregorian year — 365.2425 days, which is why leap years exist.

Sources

• NIST Special Publication 811 — Guide for the Use of the International System of Units