DATE CALCULATOR

Contracts, returns windows, notice periods and warranties are usually written in calendar days — weekends and holidays included. A 30-day return window that starts on a Friday ends on a Sunday, and plenty of people lose the window assuming they had until Monday. When a document doesn't explicitly say "business days," assume calendar days and give yourself a buffer.

What is one month after January 31? There is no February 31, so software has to make a choice. The standard convention — used here and in most spreadsheets — is to clamp to the last valid day of the target month, giving February 28 (or 29 in a leap year). It's a reasonable rule, but it means adding a month and then subtracting one doesn't always bring you back where you started. When precision matters legally, count in days.

Most U.S. legal and administrative deadlines exclude the triggering day and start the count from the next day — "within 14 days of receipt" usually means the day after receipt is day one. This calculator counts pure calendar arithmetic from the date you enter, so if a rule says "the day after," advance your start date by one before calculating.

Once you have the date, don't leave it in a browser tab. Our free reminder tool drops it straight into your own calendar as a Google Calendar event or an iCal file — created entirely in your browser, with nothing stored on our servers.