Date & Time

Date and time tools for developers: timestamp converters, cron expression parsers with next-fire-time preview, timezone math.

All Date & Time

• Unix Timestamp Converter Convert between Unix timestamps, ISO 8601, and human-readable dates.
• Cron Expression Parser Parse cron expressions, see next 10 fire times, and get plain-English descriptions.
• Cron to Plain English Translate cron expressions to natural-language descriptions.
• Time Difference Calculator Compute the difference between two timestamps. Days/hours/minutes/seconds.
• Cron Expression Builder Build cron expressions visually: pick minute/hour/day/month/weekday. See description.
• Cron Expression Decoder Decode any cron expression to plain English. See next 10 fires in your timezone.
• Timezone Converter Convert any time between timezones. Side-by-side comparison for distributed teams.
• Age Calculator (Years, Months, Days) Calculate exact age from a birthdate. Years, months, days, hours, total days lived.
• Duration Formatter (ISO 8601, Humanize) Convert between seconds, ISO 8601 duration, and human-friendly "2h 15m" strings.
• ISO 8601 Datetime Builder + Parser Construct or parse ISO 8601 datetimes. UTC, offsets, fractional seconds, durations, intervals.
• Relative Time Formatter ("2 hours ago") Format any timestamp as a relative phrase: "5 minutes ago", "in 2 weeks". 60+ locales via Intl.RelativeTimeFormat.
• Business Days Calculator (Skip Weekends + Holidays) Count business days between two dates, or add N business days to a date. Skips weekends and configurable holidays (US, UK, EU presets).
• Countdown Timer Generator (Embeddable HTML) Build a live countdown to any future date. Outputs self-contained embeddable HTML / CSS / JS snippet.
• Duration Between Two Dates (Years / Months / Days / Hours) Calculate exact duration between two timestamps. Years, months, weeks, days, hours, minutes, seconds.
• Time Since Event Counter (Live) How long has it been since X? Live count of years / days / hours / minutes elapsed since any past date.
• Day of Week from Date (Past, Present, Future) What day of the week was / will it be? Enter any date 1900-2100 and get the weekday. Plus ISO week number.
• Date to Roman Numerals (Copyright Notation) Convert a date to Roman numerals — common in copyright notices (MMXXVI). Year, month, day formats.
• IANA Timezone List (Searchable, 400+ Zones) Complete IANA timezone database. Search by city, country, offset. Current local time in each.
• Current Unix Timestamp (Live) Live Unix timestamp in seconds, milliseconds, and ISO 8601. Auto-updates every second; one-click copy.
• ISO Week Number Calculator Find the ISO 8601 week number for any date, plus the current week, with week start and end dates.
• Date Add / Subtract Calculator Add or subtract days, weeks, months, and years from any date and get the resulting date instantly.
• Unix Timestamp Converter Convert a Unix epoch timestamp to a human date and back. Seconds or milliseconds, UTC and local time.
• Date Format Converter Reformat a date from one pattern to another — ISO, US, European, custom tokens. Parse and re-emit any layout.
• Leap Year Checker Check whether any year is a leap year and list leap years in a range. Explains the divisible-by-4/100/400 rule.
• Weekday Finder — What Day of the Week Find the day of the week for any date, plus ISO weekday, day of year, ISO week, and days from today.
• Seconds to HH:MM:SS Converter Convert seconds to HH:MM:SS and back, with days, a human breakdown, and the ISO 8601 duration.
• Time Duration Calculator Calculate the duration between two date-times in years, months, days and total hours, minutes, seconds.
• Quarter of the Year Finder Find which quarter a date is in for both the calendar year and a custom fiscal year, with start and end dates.
• Decimal Time Converter Convert between HH:MM:SS and decimal hours for payroll and timesheets, plus decimal minutes and seconds.
• Nth Weekday of the Month Find the date of the first, second, third, fourth, fifth, or last given weekday in any month.
• ISO Week Date Converter Convert between a calendar date and the ISO-8601 week date (YYYY-Www-D) in both directions, with week numbers.
• Julian Day Converter (JD, MJD, JDN) Convert between a UTC date-time and the astronomical Julian Date, Modified Julian Date, and Julian Day Number.
• Day of the Year Converter (Ordinal Date) Convert a date to its day-of-year ordinal (1-366) and back, with days remaining and percent of the year elapsed.