Date Calculator
100 days after 1 January 2026 is Saturday, 11 April 2026.
How to use
- Pick the start date. It opens on today.
- Choose Add or Subtract, then enter how many years, months, weeks and days to move. Leave a box at 0 to skip it.
- The result shows the new date with its weekday and the exact number of days moved.
How it works
Years and months are applied first, then weeks and days. One year is 12 months, one week is 7 days.
If the target month is shorter than the start day, the result moves to the last day of that month. 31 January plus 1 month is 28 February, or 29 February in a leap year.
Days are real calendar days, so leap years and month lengths are handled automatically.
FAQ
What is 90 days from today?
Choose Add, put 90 in Days and leave the start date on today. The tool shows the date and the weekday.
Why does adding a month sometimes land on a different day?
Months have different lengths. When the day does not exist in the target month, the date falls back to that month's last day instead of spilling into the next month.
Is the order of years, months and days important?
Yes, in rare cases. Moving the month first and then the days can give a different result than days first. This tool always moves years and months first, then weeks and days.
How do I count the days between two dates instead?
Use the Days between dates calculator. This tool starts from one date and moves forward or back.