Add / Subtract Days from Date
Calculate a date by adding or subtracting any combination of years, months, weeks, and days. Quick presets and swap mode included.
Quick Presets
Result Date
Tuesday, June 9, 2026
Unix Timestamp
1780963200
Days from Today
Today
- Result Date
- Tuesday, June 9, 2026
- Day of Week
- Tuesday
- Days from Today
- 0
- Unix Timestamp
- 1780963200
How to use Add / Subtract Days from Date
The date add/subtract calculator lets you add or subtract any combination of years, months, weeks, days, hours and minutes to or from a starting date and time. It handles month-end edge cases correctly (e.g. adding one month to January 31 yields the last day of February) and shows the result date, Unix timestamp and days from today. Quick presets for common intervals like +30 days, +1 year or −6 months are provided.
- Enter or select the starting date and time.
- Choose + Add or − Subtract mode.
- Enter the number of years, months, weeks, days, hours and/or minutes to apply.
- The result date updates instantly. Use quick presets for common intervals.
- Swap the result into the start field for chained calculations.
Your data never leaves your device — 100% private processing.
How month arithmetic handles edge cases
Adding months is not always as simple as adding 30 days. January 31 + 1 month should yield "end of February" (28th or 29th), not March 2nd or 3rd. This calculator clamps to the last valid day of the result month, matching behaviour used by most programming languages and spreadsheet applications.
Glossary
- Unix timestamp
- The number of seconds elapsed since 1 January 1970 00:00:00 UTC.
- ISO 8601
- The international date format standard: YYYY-MM-DD.
Related reading
Frequently Asked Questions
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Why use Add / Subtract Days from Date?
- Handles timezone conversions and DST automatically
- Supports date arithmetic across years and leap years
- ISO 8601 and human-readable output formats
- Works for historical and future dates with full accuracy
Common use cases
- Calculate how many days until a project deadline
- Find the day of the week for a date in the past
- Convert meeting times across different time zones
- Calculate age from a date of birth
- Add or subtract business days for contract terms
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