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Date Add & Subtract

Find the date a whole number of days or weeks before or after another.

Local processing

Choose your date and interval

Enter a non-negative whole number, including zero. Calendar days include weekends and holidays. Dates use UTC, independent of time zone.

Your date

2026-01-02

2026-01-01 + 1 day = 2026-01-02.

Results stay between 0001-01-01 and 9999-12-31.

Your inputs stay on this device. No account or file upload needed.

A QUICK GUIDE

How to use date add & subtract

Add or subtract whole calendar days or weeks from a date. The calculation uses UTC calendar dates, so daylight saving time does not change the answer. One week always means seven calendar days.

  1. Choose a starting date.
  2. Choose Add or Subtract and enter a non-negative whole number of days or weeks.
  3. Read the resulting date or copy it in YYYY-MM-DD format.
TRY THIS EXAMPLE

Step across a leap day

2024-02-28 plus 1 day is 2024-02-29. Adding 2 days gives 2024-03-01. Subtracting 1 week from 2026-01-08 gives 2026-01-01.

Good to know

  • Supported dates range from 0001-01-01 through 9999-12-31. A result outside that range is rejected.
  • The count must be a non-negative whole number. Choose Subtract to move backwards; zero returns the starting date.
  • Every calendar day counts, including weekends and holidays. Months, years and business-day rules are not included.

Common questions

Does a daylight saving change add or remove a day?

No. The tool shifts UTC calendar dates instead of measuring elapsed local-time hours. A local 23-hour or 25-hour day still counts as one calendar day.

Why can’t I add a month?

Months have different lengths and need a rule for dates such as January 31. This version keeps the operation unambiguous by supporting only days and seven-day weeks.