Years to Days
An instant years-to-days converter, with the formula and a reference table below.
| Years | Days |
|---|---|
| 1 yr | 365.25 day |
| 2 yr | 730.5 day |
| 3 yr | 1095.75 day |
| 5 yr | 1826.25 day |
| 10 yr | 3652.5 day |
| 25 yr | 9131.25 day |
| 50 yr | 18262.5 day |
| 100 yr | 36525 day |
How to use
- Enter a value in the Years field.
- The Days figure appears immediately — no button to press.
- Typing in the Days field converts back to Years the same way.
- Use the reference table for the values that come up most often.
Years to Days formula
To convert years to days, multiply by 365.25.
day = yr × 365.25
Why this factor: the year and the day are both defined against the second, so dividing one definition by the other gives 365.25 directly. Both definitions are set out in full below.
To go the other way, divide by 365.25 — or use the Days to Years converter, which is the same calculation reversed.
Worked example
Start with 90 yr. Multiply by 365.25 to get 32872.5 day.
90 yr × 365.25 = 32872.5 day
The converter above does this for any value you type, in either direction.
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.
What is a day?
A day is 24 hours, one nominal rotation of the Earth.
Definition: Exactly 86,400 seconds by convention. The Earth's actual rotation drifts slightly, which is what leap seconds correct.
Where it is used: Calendars, project schedules, hotel and rental periods, and interest accrual.
Years vs Days
The year and the day belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many days are in a year?
One year equals 365.25 days.
What is the formula to convert years to days?
Multiply the number of years by 365.25. To reverse it, divide by 365.25 instead.
How do I convert days back to years?
Divide by 365.25, which is the same as multiplying by 0.00273785079.
How many days are in 10 years?
10 yr works out to 3652.5 day.
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 year defined?
Exactly 365.25 days, so exactly 31,557,600 seconds.