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How-to

How do I add or subtract days from a date?

Short answer

Use a browser-based date calculator: enter a starting date and a number of days, weeks, months or years, and it gives you the resulting future or past date along with the exact day of the week. It runs on your device and takes the counting-across-months work off your hands.

Moving a date forward or back

Adding time to a date means carrying across month and year boundaries correctly, so 20 days after the 25th lands in the next month, and a leap year can shift the answer by a day. A date calculator handles all of that: you give it a start date and an amount to add or subtract in days, weeks, months or years, and it returns the exact resulting date rather than an estimate.

Common reasons to do this

Date math shows up in everyday planning: a 30-day return window, a 90-day notice period, when a subscription renews, the deadline that is six weeks out, or what the date was a certain number of days ago. Knowing the resulting weekday is often just as useful as the date itself. Add is one direction and subtract is the other, and because the tool runs in your browser the dates you enter stay on your device.

Step by step

  1. Enter the start date. Pick or type the date you are counting from.
  2. Set the amount. Enter how many days, weeks, months or years to add or subtract.
  3. Read the result. The tool shows the resulting date and its day of the week, computed locally.

Frequently asked questions

Can I add weeks or months, not just days?

Yes. You can add or subtract days, weeks, months or years and get the exact resulting date.

Does it tell me the weekday?

Yes. Along with the date, it shows the exact day of the week it falls on.

Is my date sent anywhere?

No. The calculation runs entirely in your browser.

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