Add Days to Date Calculator

How to use this calculator

1. Enter the start date (year, month, and day).
2. Enter the number of days to add; use a negative number to subtract.
3. Get the resulting year, month, and day instantly.

Inputs explained

Start date

Year, month, and day of the date you’re counting from.

Days to add

Positive to move forward, negative to move backward.

When to use it

• Setting due dates or reminders a certain number of days after an event.
• Planning travel buffers or visa timelines.
• Calculating drip campaign or nurture sequence offsets.

Tips & cautions

• Use negative values to find dates before the start date (e.g., −30 days).
• For business days only, use the Business Days calculator.
• If you want weeks instead of days, multiply by 7 and enter the result.
• Counts calendar days, not business days or holidays.
• Gregorian calendar only; historical calendars may differ.
• Time zones aren’t considered—assumes local time when constructed.

Worked examples

Deep dive

FAQs

Does it include leap years?

Yes. JavaScript’s native Date object handles leap years and month boundaries automatically.

Can I subtract days?

Enter a negative number (e.g., −7) and the calculator will move backward from the start date.

Does it skip weekends or holidays?

No. It counts every calendar day. Use the Business Days calculator to exclude weekends and holidays.

Which calendar is used?

It uses the modern Gregorian calendar. Historical dates before adoption may differ.

What about time zones?

The calculation uses local time via JavaScript Date. For cross-time-zone plans, consider converting everything to UTC first.

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