Date CalculatorPrivate, Instant, In Your Browser
"What date is 90 days from today?" is the kind of question that sends people counting on their fingers across a wall calendar. Pick a start date, choose add or subtract, type the number of days, and we'll name the resulting date — weekday included, since knowing it lands on a Sunday is often the point. Month lengths and leap years are handled by the calendar arithmetic itself, entirely on your device.
Thursday, August 6, 2026
Pure calendar arithmetic, computed on your device — even works offline.
Frequently Asked Questions
What is the result's weekday good for?
Deadlines, notice periods and return windows often shift when they land on a weekend. Because we name the weekday of the resulting date, you can spot a Saturday due-date before it surprises you.
Does it handle month boundaries and leap years?
Yes. Adding days walks the real calendar, so January 31 plus 1 day is February 1, and February 28, 2028 plus 1 day is February 29 — no 30-day-month approximations anywhere.
Can I subtract days as well as add them?
Yes — flip the add/subtract selector. Subtracting is handy for working backwards from a deadline: "the 60-day notice for this date must be sent by when?"
Is anything I type sent to a server?
No. Date arithmetic is pure JavaScript running in your tab. We built the whole site so that our tools work without sending data anywhere — this page even works offline.