Date Calculator - Add or Subtract Days

Add or subtract days, weeks, and months from any date to find a future or past date.

How to use date calculator - add or subtract days

  1. Select a starting date and add or subtract
  2. Choose days, weeks, or months and an amount
  3. Check the resulting date and weekday

Worked example

January 31, 2026 + 1 month

February 28, 2026

How the result is calculated

Days and weeks move by calendar dates. Month addition preserves the day where possible and clamps to the last day of a shorter destination month.

Inputs stay in your browser. You can use this tool without joining the waitlist or creating an account.

From a calculation to a daily glance

Keep the whole month in view.

Add the resulting deadline to your calendar, then choose a monthly design in Edit Widget → Design.

  1. 1Add the events you want to see to your calendar.
  2. 2Enable that calendar in the app.
  3. 3Add Monthly Calendar; use Edit Widget → Design to choose its look.
Get early accessExplore widget designs

Web results do not automatically sync to the app. Setup is manual; calendar events appear through your enabled calendars.

February
SMTWTFS
1
2
3
4
5
6
7
Birthday ♡
8
9
10
11
12
13
14
MeetingsCelebration
15
16
17
18
19
20
21
CelebrationWorkshopMeetingProject reviewTeam dinner
22
23
24
25
26
27
28
Vacation
1
2
3
4
5
6
7
Monthly Calendar · example design from the app

Frequently asked questions

How do I add days to a date?
Choose a starting date, set the direction to 'Add', and enter how many days, weeks, or months you want to move forward. The calculator shows the resulting date and the day of the week instantly.
How do I find what date it was a number of days ago?
Set the direction to 'Subtract' and enter the number of days. The tool counts backward from your start date and shows the exact past date, including the weekday.
Can it count business days?
This calculator counts calendar days, including weekends and holidays. To keep track of upcoming dates at a glance, the Monthly Calendar Widgets month grid highlights every date and event on your iPhone Home Screen.

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