Date Add/Subtract
Add or subtract years, months, weeks, days or business days from a date, with the weekday, ROC date and month-end rules.
Result
Enter a start date and the years, months, weeks or days to add or subtract.
How to use
- Enter a “Start date”, such as 2024-05-01, 20240501 or the ROC date 113/05/01, or click “Today”.
- Choose “Add” or “Subtract”, then fill in years, months, weeks and days. Leave the rest empty.
- To count working days (for a payment deadline, say), check “Count days as business days”.
- The result shows the date, weekday, ROC date and the number of days from the start. Click “Copy” to grab it.
FAQ
What is January 31 plus one month?
February has no 31st, so the result is the last day of February: the 28th, or the 29th in a leap year. Most spreadsheets and programming languages use this month-end rule too, and the tool points it out when it happens.
In what order are years, months, weeks and days applied?
Years and months are combined and applied at once (so January 31 plus 2 months is March 31, not February 28 plus a month), then weeks (7 days each), then days.
How are business days counted? Are holidays skipped?
Business days skip Saturdays and Sundays only; public holidays are not included. From a weekend, counting starts at the nearest weekday, so Saturday plus 1 business day is Monday, as with the spreadsheet WORKDAY function.
What is February 29 plus one year?
The next year has no February 29, so by the month-end rule it is February 28. Plus 4 years lands in a leap year again, so it stays February 29.
Can I enter ROC (Minguo) dates?
Yes. 113/05/01, 1130501 and 民國113年5月1日 all work, as do full-width digits, and the result also shows the ROC date (ROC year + 1911 = Gregorian year).
Are the dates I enter uploaded?
No. Everything is calculated in your browser and never leaves your device.
Related tools
Date Difference
Count the days, weeks, months and years between two dates or times, plus weekdays. ROC (Minguo) dates work too.Countdown Timer
Run a timer (1, 5, 25 minutes or custom) or count down to a date, with pause, a sound alert, notifications and share links.ROC Year Converter
Convert ROC (Minguo) years and dates to Gregorian and back, with formats like 113/05/01 and 1130501, plus weekday and zodiac.