When this tool helps
Use a date offset when you know a starting date and a number of calendar days rather than two endpoints. Positive days move forward and negative days move backward. Calendar month lengths and leap days are handled by the date calculation.
Choose the start date, then enter a whole day count. Zero keeps the same date. This tool intentionally does not treat a “day” as a working day or skip holidays, so check contractual or official deadline rules separately.
What to enter
These are the candidate Android fields, not a form on this website. Editable fields in the app start empty; modes and units are selected separately.
- Start date
- The date from which to move.
- Days to add · negative to subtract
- A whole number between −365,000 and 365,000.
Try this example after the update is available
The values below explain the calculation. They are not a quote, a live measurement or an automatic answer for your situation.
- Start date
- 2024-03-01
- Days to add
- -1
Checked example result2024-02-29
Subtracting one calendar day from 1 March 2024 lands on 29 February because 2024 is a leap year.
Formula and assumptions
Resulting date = selected calendar date + signed whole-day offset
- Weekends and holidays are included. No country-specific business calendar is consulted.
- The output is a calendar date, not an exact timestamp or an appointment with a reminder.
A common mistake to avoid
Do not enter 1.5 to mean “one day and twelve hours.” The input accepts whole calendar days only; use duration arithmetic for hours, minutes and seconds.
Find this tool in the Android update
- When you have the redesigned Android update, open Tools and search for Add days to a date, or find it under Everyday.
- Open the tool, choose the mode or units relevant to your task, then enter your own values.
- Review the result and explanation. Use Calculate & save only if you want the calculation kept in local History; Copy result does not send it to our server.
This guide is an educational preview of the update in testing, not an announcement that Google Play has approved or published it. Calculations are in the native app; no web calculator or download is offered on this page.
Questions about Add days to a date
How do I subtract days?
Enter a negative day count, such as −1, to move backward from the selected date.
Does adding 30 days mean the same date next month?
Not necessarily. Months have different lengths; this tool adds exactly 30 calendar days, not one calendar month.