Add or Subtract From a Date

Put a minus sign in front of any amount. For example -7 in the days box moves the date one week earlier, and -1 in the years box lands on the same date the previous year. You can mix positive and negative units in one calculation.

February has no 31st, so the day clamps to the last valid day of the target month, giving February 28 in a common year and February 29 in a leap year. Only the day is adjusted; the month and year land where you asked.

Years and months are applied first as calendar arithmetic, clamping the day of month if the target month is shorter. Weeks and days are then added afterward as exact 24-hour offsets, so a month plus five days means shift the month first, then step forward five days.

Adding one year to February 29, 2024 gives February 28, 2025 because 2025 has no leap day, and the day clamps down. Adding four years would land back on February 29 when the target year is itself a leap year.

No. Each amount must be a whole number. Half days or partial months are rejected with a short message, since the result is always a clean calendar date rather than a time of day.

No. Every date is computed in UTC, so clock changes and time zones never shift the result. You always get a plain calendar date with no hidden hours attached.

Yes. Subtracting more days than remain in the month rolls back through earlier months and years automatically. Subtracting three weeks from March 15, 2026 returns February 22, 2026, stepping across the month end for you.

There is no small cap. You can shift by hundreds of years in either direction and still get a valid date, as long as the start date is a real calendar date in YYYY-MM-DD form.

Yes. The calculation runs entirely in your browser and nothing is uploaded or stored, so the dates you enter never leave your device.