Add or Subtract Days from a Date - Days, Weeks, Months, Years
Add or subtract time
Counting forwards, not counting between
Two questions about dates look alike and are not. One asks how far apart two days are; the other starts from one day and walks forward. "Ninety days from today" is the second kind, and it is the one that turns up on notices, contracts, returns policies and medical follow-ups. This page answers it, and tells you which weekday you land on, because that is usually the next thing you need to know.
Using it in three steps
- 1 The starting date is today by default. Change it if you are counting from somewhere else.
- 2 Choose forwards or backwards, then fill in any of the four amounts. You can combine them.
- 3 Read the date and the day of the week. The weekday count below is often the number people actually needed.
What happens when the month is too short
Adding a month is not adding thirty days, and the difference bites at the end of the month. One month after 31 January is 28 February - the last day of the target month - not 3 March. Many programming languages roll the overflow forward by default, and the resulting off-by-a-few-days errors are a well-worn bug. This page clamps instead, because clamping is what people mean when they say "the same date next month".
Business days are not a fixed length
The business-day mode counts only weekdays, so five business days from a Wednesday is the following Wednesday, not the Monday. That is genuinely useful for delivery windows and notice periods, but it knows nothing about public holidays, which differ by country and sometimes by region within one. If a national holiday falls inside your window, add a day for each one and the answer becomes yours rather than the tool's.