Time tools
Free time tools that run entirely in your browser. Convert between time zones using the IANA timezone database, decode Unix timestamps in seconds or milliseconds, and calculate days between dates.
Each tool uses the date and time support built into your browser, including its copy of the IANA time zone database, so daylight saving changes and leap years are handled without an extra download.
Read the complete time tools guide
How to use time tools
- Pick the tool you need from the list above.
- Enter your date, time, or timestamp in the input fields provided.
- Results appear instantly as you type or pick values.
- Copy the result or use the dedicated slug pages for specific use cases.
How the time tools work
The Unix timestamp converter builds a JavaScript Date from the number (seconds times 1000, or milliseconds as entered) and prints it in UTC, ISO 8601 and your local zone. The date calculator reads each date at local noon and counts whole calendar days, so daylight saving changes never shift a count. The timezone converter reads the wall-clock time in the source zone and formats the same moment in the target zone with Intl.DateTimeFormat, using the IANA rules that ship with the browser, and warns when a clock change skips or repeats the time you picked.
In-browser time tools vs the alternatives
| Approach | Privacy | Cost | Best for |
|---|---|---|---|
| In-browser (this site) | All local | Free | Quick conversions, timestamp decoding, day counting |
| Hosted time and meeting planners | Server-side | Free tier + paid | Scheduling polls, calendar integration, recurring invites |
| Operating system clock and calendar | All local | Free | Two-zone glances, ad-hoc reminders |
The in-browser time tools cover one-off conversions and timestamp work without leaving the page. For coordinating a meeting across many participants, a hosted scheduling tool will integrate with calendars and send invites. For long-running cross-zone collaboration, the operating system clock plus calendar may be enough.
When to use these tools
- Scheduling a meeting across regions? Use the timezone converter with the IANA database to find a workable hour for everyone.
- Debugging an API response or log entry? Decode Unix timestamps in seconds or milliseconds into human-readable dates.
- Counting down to a launch or working out how many days between two dates? Use the date difference and add or subtract tool.
- Curious about how old someone is in years, months, and days? Try the age calculator for an exact breakdown.
Frequently asked questions
- What are Time tools?
- Time tools is a collection of browser-based utilities for working with dates, time stamps, and time zones. The set currently includes a timezone converter, a Unix timestamp converter, and a date calculator.
- Are calculations accurate?
- Yes. Every tool uses the JavaScript Date API and Intl.DateTimeFormat, which rely on the IANA timezone database shipped with your browser. Leap years, daylight saving rules, and partial-hour offsets are all handled correctly.
- Do I need an account?
- All time tools are open access. Click any tool and start using it immediately. All calculations run in your browser. Our servers are not involved at any point.
- What time zones are supported?
- Every IANA zone exposed by Intl.supportedValuesOf('timeZone') is supported, currently more than 400 zones covering every region. Quick-pick shortcuts are included for major cities like New York, London, Tokyo, and Sydney.