Quick answer: Count forward from the date you start on: 4 November 2026 plus 90 days is Tuesday, 2 February 2027.
How it's calculated
Pick a date, choose Add or Subtract, and enter any mix of days, weeks, months and years. The result updates as you type. The page opens with today's date in Riyadh plus 30 days, so you see an answer straight away.
Days and weeks are exact: a week is 7 days, and the starting date itself is day 0, so 1 day after Monday is Tuesday.
Months and years follow the calendar and are applied before weeks and days. A month step keeps the day of the month, so 4 November plus 1 month is 4 December, whatever the number of days in between.
To go the other way and count the days between two dates, use the date difference calculator. For service across several jobs, use the work experience calculator; for your age, the Hijri age calculator; and to see a result on the Hijri calendar, the Gregorian to Hijri converter.
Worked examples
- 4 November 2026 plus 90 days: = Tuesday, 2 February 2027
- 15 March 2026 minus 6 weeks (42 days): = Sunday, 1 February 2026
- 31 August 2025 plus 6 months: = Saturday, 28 February 2026 (February has no 31st)
Adding months at the end of a month
When the day you start on does not exist in the new month, the result moves back to that month's last day. So 31 January 2025 plus 1 month is 28 February 2025, and 31 January 2024 plus 1 month is 29 February 2024 because 2024 is a leap year.
Years work the same way: 29 February 2024 plus 1 year is 28 February 2025. If you enter months and days together, the months come first, so 31 January 2025 plus 1 month and 1 day is 1 March 2025.
Because months differ in length, “1 month” and “30 days” can give different dates. Use days when a contract or notice period is stated in days.
Frequently asked questions
What date is 90 days from today?
Enter 90 in Days with today's date selected. The page fills in today's date in Riyadh when it opens.
Is the starting date counted?
No. The starting date is day 0, so 1 day after 4 November is 5 November. If your notice or deadline counts the first day as day 1, subtract 1 from the number of days.
How do I subtract days from a date?
Choose Subtract, then enter the number of days, weeks, months or years. 15 March 2026 minus 6 weeks is 1 February 2026.
What is 31 January plus one month?
28 February, or 29 February in a leap year. When the day does not exist in the new month, the last day of that month is used.
Are weekends or public holidays skipped?
No. Every calendar day counts. To count only working days between two dates, use the date difference calculator.
Do you save the dates I pick?
No. The days are added in your browser and forgotten when you close the page. They aren't sent to us or written into the link.