Time & Date Calculators

Built for anyone converting a date and time between time zones — scheduling a call across countries, working out what time a message lands, or checking what time it is somewhere else — for anyone turning daily clock-in/clock-out times into an hours or payroll total, whether that’s a personal timesheet or a small team’s, for anyone working out an exact age from a date of birth, and for anyone counting the days between two dates, adding or subtracting days, or working out a business-day deadline.

Use the Time Zone Converter for single-instant conversion (one date/time, compared across as many zones as you add) with live daylight-saving handling pulled from your browser’s own time zone database rather than a printed chart. Use the Timesheet Calculator for a weekly, biweekly, or monthly grid of clock-in/clock-out times with lunch-break deduction, an optional overtime threshold, and an Excel export. Use the Age Calculator for an exact years/months/days age from a date of birth, as of today or any other date, with Excel/SQL/code formula references alongside it. Use the Days Calculator when the question is about a span between two dates instead — the total days between them, a date plus or minus a number of days, or a business-day count excluding weekends and holidays.

Use the Time Unit Converter when the question is a duration rather than a date — nanoseconds through fortnights on exact factors, with months and years shown as calendar ranges because neither has a fixed length.

If you specifically need a Unix timestamp, a Discord message-timestamp code, or a plain 12-hour ↔ 24-hour military-time conversion with no zone change involved, those are separate, more specialized tools that are planned but not yet published — see the FAQs below for the current state.

1. 1Enter the date and time you have, and the zone it’s in, in the Time Zone Converter.
2. 2Use a popular pair (EST to IST, IST to GMT/BST, and more) as a shortcut for the most commonly searched conversions.
3. 3For hours worked, pick a period length in the Timesheet Calculator and enter each day’s clock-in, clock-out, and break.
4. 4Turn on the overtime threshold if it applies, then use Download Excel to keep a copy of the totals.
5. 5For a deadline or date-duration question, use the Days Calculator to count days between dates, add/subtract days, or count business days excluding weekends and holidays.

• Assuming a zone’s abbreviation (like EST or CST) always means the same offset — several abbreviations are reused for unrelated zones on different continents; the converter always shows the full UTC offset alongside any abbreviation.
• Forgetting that a converted time can land on the next or previous calendar day — always check for the +1 day / −1 day marker before booking something.
• Treating a fixed-offset zone like India (IST) the same as a zone that observes daylight saving — the gap between them changes by an hour twice a year even though IST itself never moves.
• Assuming the Timesheet Calculator’s overtime option applies your specific state, country, or employer’s exact rules — it’s a single configurable weekly threshold, not a jurisdiction-specific calculation.
• Assuming the Days Calculator’s business-day mode automatically excludes public holidays — it only removes weekends and whatever holiday dates you explicitly list.

The Time Zone Converter is accurate for essentially all everyday and business scheduling use, but depends on your browser and operating system having an up-to-date time zone database — a device that hasn’t updated in a long time may not yet reflect a very recently changed political time zone or DST rule. For legal, contractual, travel, or safety-critical timing (flight departures, court deadlines, financial settlement windows), confirm with an authoritative source rather than relying on any calculator alone. The Timesheet Calculator applies simple, transparent arithmetic — it is not a substitute for your employer’s payroll system or a program’s mandated timesheet system, and does not implement jurisdiction-specific overtime law. The Days Calculator does not know public holidays automatically for any country or company, and is not a substitute for the specific counting method a legal document, contract, or payroll system requires.

The Time Zone Converter does not maintain its own offset table — every conversion is computed live from the browser’s built-in time zone API, which implements the IANA Time Zone Database, the authoritative source used by nearly every operating system and programming language worldwide. The Timesheet Calculator uses plain clock-time arithmetic; its optional overtime model is structured after the US Fair Labor Standards Act’s weekly-threshold concept as a generic, configurable reference point, not as jurisdiction-specific guidance. The Days Calculator uses standard Gregorian calendar-date arithmetic, with leap years applied automatically.

See the Methodology for how calculators are built and reviewed, who runs the site, the Disclaimer for the full terms, and the Contact page to report an issue.

Created and maintained by Jay Sudha, finance educator · Last reviewed 15 September 2026. See a formula issue, unclear assumption, or broken result? Report it through the contact page.