Date Calculator
Add or subtract days, weeks, months or years from a date.
About this tool
Adds or subtracts calendar days, weeks, months or years, or weekdays only. Adding a month to the 31st lands on the last day of shorter months (31 January plus one month is 28 or 29 February). Public holidays are not skipped.
Need the date 90 days from today, the end of a 6-month notice period, or 10 working days before a deadline? Choose a start date, whether to add or subtract, an amount and a unit, and the calculator gives the resulting date, its day of the week and how many calendar days apart the two dates are. You can count weekdays only for business-day deadlines.
How to use the Date Calculator
- Pick a start date; today is filled in for you.
- Choose add or subtract and enter the amount.
- Choose days, weeks, months or years. For days, you can count business days only.
- Read the resulting date and the day of the week.
90 days from 16 October 2026
Adding 90 days to Friday 16 October 2026 gives Thursday 14 January 2027. Adding 90 business days instead, skipping weekends, gives Friday 19 February 2027, 126 calendar days later. Adding 3 months gives 16 January 2027, which shows that 3 months is not the same as 90 days.
How months, years and business days are counted
Days and weeks are simple: a week is always 7 days. Months are counted on the calendar, so the day number stays the same: 15 March plus one month is 15 April. When the target month is shorter, the date moves to its last day, so 31 January plus one month is 28 February, or 29 February in a leap year. Years work the same way, so 29 February 2028 plus one year is 28 February 2029. Business days skip Saturdays and Sundays but not public holidays, which differ by country; if a holiday falls inside the period, add a day for each one. Legal and contract deadlines can have their own counting rules, so check those when it matters.
Frequently asked questions
What date is 30 days from today?
Choose today as the start date, add 30 days and read the result. It also shows the day of the week.
Are public holidays skipped in business days?
No. Only Saturdays and Sundays are skipped, because public holidays vary by country. Add one day for each holiday in the period.
Why is 1 month not 30 days?
Months have 28 to 31 days, so adding a month keeps the same date in the next month instead of adding a fixed number of days.
How do I count the days between two dates?
Use the date difference calculator for that; this tool goes from a date and an amount to a new date.