Ready to calculate
Choose a mode, enter values, and calculate the result.
Formula used
Days to years: Years = Days ÷ Days per year
Years to days: Days = Years × Days per year
Different standards use slightly different year lengths. Select the standard matching your purpose. The Gregorian average is useful for long-term estimates.
How to use this calculator
- Select the required calculator mode.
- Choose a year definition or enter a custom value.
- Enter days, years, or dates.
- Choose precision and date-counting options.
- Press Calculate to view detailed results.
- Copy, print, or export the result.
Example conversions
| Days | Common years | Gregorian years | Approximate weeks |
|---|---|---|---|
| 30 | 0.082192 | 0.082137 | 4.285714 |
| 90 | 0.246575 | 0.246412 | 12.857143 |
| 365 | 1 | 0.999336 | 52.142857 |
| 730 | 2 | 1.998672 | 104.285714 |
| 1,000 | 2.739726 | 2.737907 | 142.857143 |
Frequently asked questions
How many days are in one year?
A common year has 365 days. A leap year has 366 days.
What is the average Gregorian year?
The Gregorian average year contains 365.2425 days. It reflects the calendar’s leap-year rules.
What is a Julian year?
A Julian year equals exactly 365.25 days. Astronomy often uses this fixed definition.
Can I convert decimal days?
Yes. The calculator accepts whole and decimal day values.
Can I use negative values?
Yes. Negative conversions and backward date calculations are supported.
How are remaining days calculated?
Complete years are removed first. The unused portion appears as remaining days.
Does business-day mode exclude holidays?
No. It excludes Saturdays and Sundays only. Public holidays require a local calendar.
Should the start date be included?
Include it when the first date counts as day one. Otherwise, leave it excluded.
Why do year results differ?
Results differ because each year standard uses another conversion factor.