Free Online Add or Subtract Days Tool
An add-or-subtract-days tool shifts a starting date by an integer day count and returns the new date in ISO 8601, locale and weekday form.
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How to Use This Tool
- Pick a start date.
- Choose Add or Subtract.
- Enter the number of days to shift the date by.
- Read the resulting date, weekday and ISO 8601 form in the result panel.
What Is an Add or Subtract Days?
Of the date-calculator family, add-days is the simplest member: pick a starting date, type a count, get the date that many days away. It answers questions like "what date is 90 days from today?" (common in mortgage closings, visa applications and SLAs) or "what date was 30 days ago?" for back-dating an invoice. Unlike the multi-unit date calculator, this tool keeps the input to a single integer for fast lookup.
Legal teams handling notice periods rely on it for deadline math; contract administrators verify response windows; travel planners spot whether their proposed return date lands on a weekend. The tool counts calendar days, so weekends and public holidays are included — for working-day math, use the Work Days Calculator instead. Negative numbers are accepted; you can also flip the operation between Add and Subtract for readability.
The result shows the new date in your local format, as an ISO 8601 string for copy-paste into spreadsheets or APIs, and the weekday name so you know whether the target lands on a Saturday before committing.
Frequently Asked Questions
Can I go backward in time?
What date format does it accept?
Does it skip weekends?
Published by the WeGotEveryTool team. We build and test every tool in-house and update pages when the underlying spec, formula, or recommendation changes.
Reviewed: May 2026. Disclaimer: this tool is provided as-is for general informational use. For decisions with material consequences (medical, legal, financial, security) verify results against a qualified professional source.
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