Add or Subtract Days from a Date
Start from any date, then move it forward or backward by days, weeks, months or years. Datewise gives you the resulting date, the weekday it lands on, and how far it sits from where you started.
How to shift a date
Choose the start date
Set the date you are counting from. It defaults to today, so for "30 days from now" you only need to press calculate.
Add or subtract
Pick a direction, then fill in any mix of years, months, weeks and days. Leave the fields you do not need at zero.
Get the exact date
See the resulting date written out, the day of the week it falls on, and the total number of days you moved.
When this comes in handy
Deadlines and reminders
Work out the date 90 days from signing, two weeks before an event, or six months after a purchase, without paging through a calendar.
Plans and returns
Find a return-by date, a renewal date, or the day a waiting period ends, and know in advance whether it lands on a weekend.
Everyday scheduling
Count forward to a due date or back to a start date for anything from a project timeline to a health milestone.
How date shifting works
Moving a date by a whole number of days is straightforward: the calculator adds or removes that many days on the calendar, rolling across month and year boundaries automatically. Weeks are just handled as sevens of those days. Months and years take a little more care, because they do not have a fixed length.
Months and years first, then days
When you add months or years, Datewise adjusts the month and year first, keeping the same day number where possible. It then applies any weeks and days on top. This mirrors how people describe dates naturally — "three months and ten days from now" — and keeps the result predictable.
End-of-month clamping
Adding one month to 31 January cannot land on 31 February, because that date does not exist. In cases like this the day is clamped to the last valid day of the target month, so 31 January plus one month becomes 28 February, or 29 February in a leap year. The same rule applies to a 29 February start date shifted into a non-leap year.
The total-days figure
Alongside the result, you get the plain number of days between your start date and the new one. Because months vary in length, adding "one month" will show as 28, 30 or 31 days depending on where you started — which is exactly right.
Frequently asked questions
Can I combine years, months, weeks and days at once?
Yes. Fill in any combination and they are applied together. Years and months are handled first, then weeks and days are added on top of that date.
What happens when the day does not exist in the target month?
The day is clamped to the last day of that month. So 31 January plus one month gives 28 February, or 29 February in a leap year, rather than spilling into March.
Does it tell me the day of the week?
Yes. The result includes the weekday the new date falls on, which is useful for spotting when a deadline lands on a Saturday or Sunday.
Can I count backwards in time?
Switch the direction to subtract and the same fields move the date into the past instead of the future, with the same clamping rules.
Why does adding one month not always add the same number of days?
Because calendar months are different lengths. "One month" from the start of February is 28 days, but from the start of July it is 31. The tool follows the real calendar.
Is my data kept?
No. Everything is calculated in your browser. The dates and numbers you enter are never uploaded or stored.