Does this account for daylight saving time?

Yes. Each conversion is evaluated against the IANA Time Zone Database for the specific date you enter, so DST transitions and historical offsets are handled correctly.

Why use IANA names instead of abbreviations like EST or PST?

Abbreviations are ambiguous (CST means both Central Standard Time and China Standard Time) and don't encode DST rules. IANA identifiers like America/Chicago resolve to a single zone with a known offset history.

What happens during a DST spring-forward gap?

Times that fall in the skipped hour (e.g. 02:30 on a US spring-forward Sunday) don't technically exist; the converter normalizes them forward by the offset shift so the output still represents a real instant.

Does my date data leave the browser?

No. Conversions run entirely on your device using the browser's built-in Intl API. No timestamps are sent to a server.

iana zones · dst aware · live · local

Convert times across timezones

Pick a source zone and a moment, then see the same instant in every target zone you care about. Uses Intl with full IANA tzdata.

Quick Start

How to convert a moment across timezones

The same instant in time has a different wall clock in every zone. Pick a source, pick a moment, see every target.

01
Pick a source zone
The zone whose wall clock you're typing in.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
sourceISO 8601RFC 3339epochlive
from · timestampiana · ISO
```
America/New_York
```
loaded · ISO 8601zone · ready
02
Type a moment
Local date and time in the source zone.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via Intl.DateTimeFormat.
whenUTC mathIntlDST-safelive
moment · optionslocal · live
```
2024-06-15 14:30
```
options applied · UTCDST-safe
03
Add target zones
Tokyo, London, Sydney — anywhere in the IANA database.
Output respects the chosen timezone offset (Z vs +05:30) and pads digits per ISO conventions so sorts stay chronological.
targetsoffsetzone-awaresortablepadded
to · computedn · ready
```
UTC · Europe/London
Asia/Tokyo · Australia/Sydney
```
computed · instantsortable
04
Read converted times
DST is applied automatically based on the date.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
liveclipboardno oracledeterministicclient-side
ok · copiedlive · done
```
Sat, Jun 15 03:30 JST+09
```
shipped · ready to shipsuccess

Pro tips

Time math without DST landmines

Always store UTC

Convert to local for display only. UTC storage avoids DST jumps and timezone drift in databases.

Watch leap seconds

POSIX time doesn’t count leap seconds; some systems do. Don’t use timestamps for sub-second precision across boundaries.

Prefer Temporal eventually

The Date API has many quirks. Temporal is shipping in modern engines and handles zones correctly.

Cron is timezone-tricky

Cron expressions run in the daemon’s local zone unless told otherwise. Pin a TZ explicitly for predictable runs.

ISO 8601 sorts naturally

YYYY-MM-DDTHH:mm:ss sorts correctly as a string. Don’t use US-style MM/DD/YYYY for anything machine-readable.

Beware Y2K38

Signed 32-bit Unix timestamps overflow in 2038. Use 64-bit storage end-to-end for long-lived systems.

Use Cases

When to convert across timezones

Scheduling meetings, debugging logs, shipping reminders.

Cross-team meetings

Confirm 2pm New York with London, Tokyo, Bangalore. Math runs in UTC under the hood to dodge DST jumps — local time is only for display. That means scheduling logic and date diffs survive March / November fall-back without the classic off-by-one-hour bug.

DST-safe

Log correlation

Match UTC server logs with the user's local time. Browser clock is the only source — no external time server, no privacy leak, no rate limit. Pair with NTP-synced server time for high-accuracy use cases, but for human-scale work the browser clock is plenty.

UTC-correct

Cron migrations

Compare local cron to UTC cron when moving infrastructure. ISO 8601 output sorts naturally as strings, perfect for filenames (report-2026-01-15.pdf) and log lines that need chronological ordering without parsing. Drop into S3 keys for free time-bucketing.

ISO-sortable

API testing

Validate timestamp parameters across regional endpoints. Pairs cleanly with cron, scheduled tasks, and timestamped log analysis. The tool's output drops directly into APScheduler, Linux cron, or GitHub Actions schedule expressions without re-formatting.

spec-grade

Launches

Coordinate a launch moment across continents. Output respects the chosen timezone offset (Z vs +05:30) so REST APIs and database TIMESTAMP WITH TIME ZONE columns round-trip cleanly. No ambiguity between "noon UTC" and "noon local".

zone-aware

Travel planning

Check arrival time in destination zone vs origin. Confirms the difference between epoch seconds (10 digits) and milliseconds (13 digits) before you commit code that mis-multiplies by 1000 — a classic bug in cross-language time handling.

epoch-accurate

FAQ

Frequently asked questions

Is DST handled correctly?

Yes — Intl.DateTimeFormat applies the IANA rules for the date you pick, so DST transitions are observed.

Does the source zone matter?

Yes. The same wall-clock 2024-06-15 14:30 is a different UTC instant in New York vs Tokyo.

What if my zone isn't listed?

The dropdown shows common cities. Any IANA tz ID works — paste a custom value through your browser's autofill or use Timezone Finder.

Can I export the converted times?

Yes — copy as TSV or download as .txt.

Is anything sent to a server?

No. All conversion runs locally using the Intl API in your browser.

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