How to use the Date Calculator
- Choose the start date (today is filled in).
- Pick add or subtract and enter years, months, weeks and/or days.
- Read the resulting date, weekday and week number.
How date arithmetic works
Years and months are added first, then weeks and days. Adding one month to 31 January gives the last day of February (28 or 29), because February has no 31st — the calculator always clamps to the end of the month rather than spilling into March. Days are counted on the calendar, so “30 days after 1 June” is 1 July.
Business days
Tick “business days only” to skip Saturdays and Sundays — useful for delivery estimates, notice periods and payment terms such as “net 10 business days”. Public holidays vary by country and are not removed.
Common questions it answers
- What date is 90 days from today?
- What was the date 6 weeks ago?
- When does a 3-month notice period end?
- What date is 1,000 days after my birthday?
To count the days between two dates instead, use a days-between-dates calculator.
Popular pages
Frequently asked questions
What is 90 days from today?
Enter today’s date (pre-filled) and add 90 days — the result shows the exact date and weekday.
Does it include the start date?
No. Adding 1 day to Monday gives Tuesday. That matches how deadlines are usually counted.
How are months of different lengths handled?
Adding months keeps the same day number where possible and otherwise uses the last day of the month.