one instant · many zones

Timestamp Timezone Converter

Q: How do I convert a timestamp to a specific timezone in JavaScript?

Use Intl.DateTimeFormat with the timeZone option: new Intl.DateTimeFormat("en-GB", { timeZone: "Asia/Tokyo", dateStyle: "short", timeStyle: "medium" }).format(new Date(ts * 1000)) . JavaScript has no native zoned datetime type yet — the Temporal API will add one.

Enter a Unix timestamp once and see it rendered in every timezone that matters to you — side by side, with IANA identifiers and correct DST offsets for the exact instant. Add, remove, reorder and copy any row.

Unix timestamp or date

Timestamps are timezone-free

A Unix timestamp answers "how many seconds since 1970-01-01 00:00:00 UTC?" — an absolute question with one answer worldwide. Timezones describe how a region displays that instant. Confusing the two is the source of most time bugs: store and transmit timestamps (or UTC instants), and only apply a zone when showing a wall clock to a human.

Worked example

Timestamp 1758000000 is the same moment everywhere:

Timezone	Local time	Offset
UTC	2025-09-16 05:20:00	+00:00
America/New_York	2025-09-16 01:20:00	−04:00 (EDT)
Europe/London	2025-09-16 06:20:00	+01:00 (BST)
Asia/Kolkata	2025-09-16 10:50:00	+05:30 (IST)
Asia/Tokyo	2025-09-16 14:20:00	+09:00 (JST)
Australia/Sydney	2025-09-16 15:20:00	+10:00 (AEST)

Notice New York is on EDT (−4) and London on BST (+1) — summer offsets. In January the same zones would show −5 and +0. Fixed-offset conversions get this wrong; the IANA database this tool uses never does.

Need the full format set?

The universal converter below adds milliseconds, microseconds, nanoseconds, ISO 8601, RFC 3339, RFC 2822 and relative time for any single zone.

Timestamp or date

Interpret input as

Display timezone

Accepts Unix timestamps (s / ms / µs / ns), ISO 8601, RFC 2822 and common date strings.

Frequently asked questions

Does the timestamp change when I change the timezone?

No — that is the key insight. A Unix timestamp is an absolute instant, identical everywhere on Earth. The timezone only changes the human-readable rendering: timestamp 1758000000 is 05:20 UTC, 01:20 in New York (EDT) and 14:20 in Tokyo, all describing the same moment.

What are IANA timezone identifiers?

Names from the IANA Time Zone Database (tzdata), the standard reference for world timezone rules — for example America/New_York, Europe/London, Asia/Kolkata. They encode the full history of a region's offsets and DST rules, unlike fixed offsets such as UTC−5, which are wrong for part of the year.

How do I convert a timestamp to a specific timezone in JavaScript?

Use Intl.DateTimeFormat with the timeZone option:

new Intl.DateTimeFormat("en-GB", { timeZone: "Asia/Tokyo", dateStyle: "short", timeStyle: "medium" }).format(new Date(ts * 1000))

. JavaScript has no native zoned datetime type yet — the Temporal API will add one.

Why do some timezones have 30- or 45-minute offsets?

Offsets follow politics, not astronomy. India uses UTC+05:30, Nepal UTC+05:45, parts of Australia UTC+08:45 or UTC+09:30. This converter uses the IANA database, so every historical and current offset — including these — resolves correctly.

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