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TOOL TOPIC

Date, business day & time tools

Calculate deadlines, add or subtract dates, compare durations, and convert common date and time formats.

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Common tasks in this topic

Tools for business-day calculations, date arithmetic, durations, ISO 8601, Unix timestamps, calendars, countdowns, and time conversion.

1
Add or subtract business days from a date
2
Calculate differences between dates or times
3
Parse ISO 8601 and Unix timestamp values

Tools in this topic

Choose the tool that most closely matches the task you need to finish.

Business days from a date calculatorAdd N business days to a start date while skipping weekends and optional excluded dates.Open  →Business days before a date calculatorSubtract N business days from a date while skipping weekends and optional excluded dates.Open  →3–5 business days date range calculatorConvert a business-day range such as 3–5 days into earliest and latest calendar dates.Open  →ISO 8601 date parser and converterParse an ISO 8601 datetime and convert it to UTC, local time and Unix timestamps.Open  →ICS / iCalendar checkerCheck VCALENDAR / VEVENT structure, UID, DTSTART and basic fields.Open  →Japanese era / Gregorian date converterConvert Japanese era dates and Gregorian dates line by line.Open  →Unix timestamp converterConvert Unix seconds / milliseconds and human-readable dates.Open  →Age calculatorCalculate age from a birth date and target date.Open  →Date difference calculatorCalculate the difference between two dates in days and weeks.Open  →Business days calculatorCalculate business days between two dates with optional Japanese holidays, custom working weekdays, endpoint inclusion, and custom closure dates or ranges.Open  →Date add / subtract calculatorAdd or subtract days/weeks from a date.Open  →Time duration calculatorCalculate elapsed time between two clock times, including overnight.Open  →Run a Countdown Timer in Your BrowserCount down from a chosen duration in your browser.Open  →Run a Stopwatch with Lap Times in Your BrowserMeasure elapsed time and lap times in your browser.Open  →Weekday calculatorCalculate weekday, day of year, and nearby dates with the same weekday.Open  →ISO week calculatorCalculate ISO week number, ISO week-year, and the week start/end dates.Open  →Time zone converterConvert date/time values between IANA time zones and inspect UTC, offset, and localized output.Open  →Date / time format converterConvert a date/time value to ISO 8601, RFC 3339, Unix seconds/milliseconds, and localized forms.Open  →iCalendar / ICS event generatorCreate a downloadable ICS calendar event from title, dates, location, and description.Open  →Date range list generatorGenerate a list of dates from a start, end, and interval.Open  →Recurring date generatorGenerate recurring dates by day, week, month, or year from a start date.Open  →Deadline date calculatorCalculate a deadline after a number of calendar days or weekdays.Open  →Multi-time-zone meeting finderFind meeting times that fall inside working hours for multiple UTC offsets.Open  →Date range overlap checkerCheck whether two date ranges overlap and calculate the overlapping dates and duration.Open  →Time slot generatorGenerate appointment time slots from start/end times, slot duration, and interval.Open  →

Related guides

Use these when you need the decision context around the tools.

“Three business days later” sounds simple—until a holiday gets in the way.Review decisions, failure points and workflow context.Read →Why the same cron expression can behave differentlyReview decisions, failure points and workflow context.Read →

Browse by use case

Start from the job and follow the tools used in that workflow.

Office & data workChoose related tools from a practical workflow.Open →

Related references

Keep the relevant formats and units close while you work.

ISO 8601Open the related reference guideOpen  →Date formatsOpen the related reference guideOpen  →World calendarsOpen the related reference guideOpen  →