Date, Time & Timezone Tools
Timestamps, business-day maths and meeting windows that actually respect daylight saving in every city involved.
Built for remote teams, project managers, developers. 25 tools published.
Age Calculator
Months are not a fixed length, so dividing days by 365.25 gives a different answer from the calendar. This uses the calendar method every official form uses.
🕑App Review Buffer
Reserve review and correction time before a coordinated launch date.
🕑Business Days
Counting the start day or not changes the answer by a day, and nobody states which they mean. Count between two dates, or add days to one, with both conventions shown.
🕑Coursework Balance
Weight available study hours by course demand and current difficulty.
🕑Date Calculator
Days are exact. Months clamp to the end of a shorter month and never come back, which is why monthly billing drifts after its first February.
🕑Date Format Tester
In Unicode patterns YYYY is the week-numbering year. 31 December 2019 renders as 2020, which is where the New Year date bugs come from.
🕑Days Between Dates
Total days, working days, weekends and the exact years-months-days breakdown — plus the answer to whether the count should include the end date, which is where people differ.
🕑Deadline Buffer
Compare elapsed time, completed work and planned buffer in one progress signal.
🕑Epoch Rollover
It does not crash. It wraps to minus two billion and reports a date 137 years in the past, which is far harder to notice.
🕑Excel Serial Date
Serial 45658 is 1 January 2025. Serial 60 is 29 February 1900, a date that never happened — and Excel still ships that bug on purpose.
🕑FILETIME Converter
The 18-digit number in a registry export or an Active Directory dump. Too large for a JavaScript number, so parsing it the obvious way loses digits.
🕑Focus Fragmentation Cost
Convert daily context switches and recovery time into weekly capacity cost.
🕑Hours Between Times
Writing the clock form where payroll wants decimal loses 18 minutes an entry. Overnight shifts subtract to a negative unless you handle the wrap.
🕑HTTP Date Header
Expires and Last-Modified want \u201cMon, 10 Aug 2026 12:34:56 GMT\u201d \u2014 English month names, literal GMT, no milliseconds. Anything else is silently ignored.
🕑ISO 8601 Date Format
Build a valid ISO 8601 string, or paste one and see exactly how it is interpreted — including why a date without a time lands in a different day.
🕑ISO 8601 Duration
The same letter M means month before the T and minute after it. Paste a duration to see the parts, and where a conversion to seconds is genuinely undefined.
🕑Play Test Deadline
Calculate the earliest production-access date, track the twelfth tester and see how one dropout can reset that tester's continuous-day clock.
🕑RACI Matrix
Turn task-role assignments into a matrix with accountable and responsible conflict checks.
🕑Seconds to Duration
90061 seconds is 1d 1h 1m 1s. Paste a number to format it, or type a duration to get seconds back — with the zero components dropped.
🕑Stopwatch & Timer
Counting setInterval ticks loses time on every late fire. This reads the clock instead, so it stays accurate even when the tab is throttled.
🕑Time Zone Meeting Planner
Pick three cities and a working window, and see every hour scored green, amber or red for all of them at once — with real IANA timezone data, so daylight saving is handled.
🕑Timestamp Unit
1000000000 is September 2001 in seconds and January 1970 in milliseconds. Both parse, so validity cannot decide it. Here is every reading at once.
🕑Timezone Converter
New York is not always UTC-5. It is UTC-4 for eight months of the year. This converts for the exact date you pick, using the real timezone database in your browser.
🕑Unix Timestamp Converter
Paste any epoch number and it works out whether you gave it seconds, milliseconds or microseconds — then shows the date in UTC, your local zone and every common format.
🕑Weekly Timesheet
Whether overtime counts daily or weekly changes identical work by four hours of pay. A compressed week is where the two rules part company.