About DateWise

DateWise is an independent website with free date and time calculators. It was started by the Crushjs Team after one too many arguments about whether a 30-day notice period ended on a Tuesday or a Wednesday, and a video call that one person joined an hour early because of daylight saving time.

What we believe

• Exact beats approximate. Our tools count real calendar days, including leap years and months of different lengths, instead of using averages.
• Show the steps. Every calculator explains its method and lists each step, so you can check it yourself.
• Your dates are yours. All calculations happen in your browser; nothing you type is sent to us.

How we keep results accurate

Date math on DateWise uses the Gregorian calendar and the international standard ISO 8601 for week numbers. Time zone conversions use the IANA time zone database built into your browser, which is the same data that phones and computers use and is updated with every browser release. Holiday dates come from fixed rules (such as the fourth Thursday of November) or, for lunar holidays, from published tables that we cite on each page. We test our results against worked examples and correct the pages when rules change.

Important note

DateWise is a planning tool. Legal deadlines, notice periods, visa stays and contract terms can follow special counting rules (for example, excluding the first day or extending to the next working day). When the date matters legally, confirm it with the organization or a qualified professional.

Get in touch

Found a bug or want a tool we don't have yet? Tell us on our contact page.