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Date arithmetic

Add & Subtract Dates

Date Add & Subtract - free online add subtract date calculator tool with instant results. Use it for date, age,

No data stored Instant results Mobile-first 100% Free

Outputs

Smart roll

  • Month-end clamping
  • ISO week metadata

Base date & shift

Months/years use calendar rules (e.g. Jan 31 + 1 month → Feb end).

Guide, FAQs & related tools

What Is a Date Add & Subtract?

A date add/subtract calculator rolls a calendar date forward or backward by a chosen amount. Months and years use real calendar rules (e.g. Jan 31 + 1 month → Feb 28/29). We show the result in ISO format, weekday name, ISO 8601 week number and ordinal day of year.

Deadlines, contract notices, warranty windows and project milestones often need “30 days from signature” or “one year from today” without spreadsheet errors.

How to Use the Date Add & Subtract - Step by Step

  1. 1

    Pick a base date

    Use the date picker — format YYYY-MM-DD.

  2. 2

    Choose add or subtract

    Toggle direction.

  3. 3

    Enter amount and unit

    Days, weeks, months or years (whole numbers for months/years).

  4. 4

    Calculate

    Get the new date with weekday and ISO week metadata.

Frequently Asked Questions - Date Add & Subtract

Guide & insights

Date Add & Subtract — complete guide

Clear explanations, practical tips and how this free date add & subtract fits real workflows — optimized for reading on any device.

What is the Date Add & Subtract?

A date add/subtract calculator rolls a calendar date forward or backward by a chosen amount. Months and years use real calendar rules (e.g. Jan 31 + 1 month → Feb 28/29). We show the result in ISO format, weekday name, ISO 8601 week number and ordinal day of year.

Why people use this calculator

Deadlines, contract notices, warranty windows and project milestones often need “30 days from signature” or “one year from today” without spreadsheet errors.

How to use the Date Add & Subtract — summary

  • Pick a base date: Use the date picker — format YYYY-MM-DD.
  • Choose add or subtract: Toggle direction.
  • Enter amount and unit: Days, weeks, months or years (whole numbers for months/years).
  • Calculate: Get the new date with weekday and ISO week metadata.

Tips for best results

For official age proofs, always use documents issued by authorities — online calculators are for planning and curiosity. For legal contracts or immigration, confirm calendar rules (leap years, time zones) against official requirements.