What's the IANA Time Zone Database?

Also called tz database or zoneinfo, it's the authoritative catalog of historical and current timezone rules maintained by IANA. Most operating systems and runtimes ship a copy and update it several times a year.

Why does Buenos Aires have such a long zone name?

Argentina has multiple provinces with slightly different historical offsets. Each gets its own identifier (America/Argentina/Buenos_Aires, America/Argentina/Cordoba, etc.) so historical timestamps round-trip correctly.

Should I prefer canonical or alias zone names?

Prefer canonical names like Asia/Kolkata over deprecated aliases like Asia/Calcutta. The finder marks aliases and points to the canonical identifier.

Is the search done locally?

Yes. The zone list is bundled with the page and queried in your browser. Nothing is sent to a server.

IANA · search · live offsets · live

Find any IANA timezone

Search the IANA timezone database by city, region or country. Each match shows the live UTC offset and current local time.

Timezone Finder

Query

(all)

Matches

of 53

Database

IANA

live

Mode

client

no server

input · query

Tip

Type a city like "kolkata", a region like "europe", or a country abbrev like "us". Click a card to copy the IANA id.

Result count

output · zones

Quick Start

How timezone search works

The IANA database uses Continent/City IDs. We match substring across the full list and show the live offset using browser Intl.

01
Type a fragment
"york" finds America/New_York; "asia" finds every Asian zone.
Parsing accepts ISO 8601, RFC 3339, RFC 2822, and Unix epoch seconds/milliseconds. The Date constructor handles the rest with browser-engine consistency.
queryISO 8601RFC 3339epochlive
q · timestampstring · ISO
```
q: "kolkata"
```
loaded · ISO 8601zone · ready
02
Read offsets
Offset is computed live — DST-aware.
All math runs in UTC internally to avoid DST landmines; presentation converts back to the user’s zone via Intl.DateTimeFormat.
offsetUTC mathIntlDST-safelive
UTC · options±HH:mm · live
```
UTC+05:30
```
options applied · UTCDST-safe
03
Click to copy
One click puts the IANA id on your clipboard.
Output respects the chosen timezone offset (Z vs +05:30) and pads digits per ISO conventions so sorts stay chronological.
copyoffsetzone-awaresortablepadded
→ · computedclip · ready
```
Asia/Kolkata
```
computed · instantsortable
04
Paste into code
Use the id in Intl.DateTimeFormat or any library accepting IANA names.
Copy writes via the Async Clipboard API; nothing pings a time server — the browser’s clock is the only oracle.
useclipboardno oracledeterministicclient-side
✓ · copiedready · done
```
new Date().toLocaleString("en", { timeZone: tz })
```
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 search timezones

Scheduling, logging, internationalisation.

Scheduling

Pick the right zone before sending a calendar invite. 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

Logging

Standardise on IANA IDs in your structured logs. 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

User onboarding

Map user-provided city to an IANA zone for storage. 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

Code lookups

Find the exact identifier accepted by Intl APIs. 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

Travel apps

Surface local time for destinations on your itinerary. 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

Multi-region

Compare offsets across regions for capacity planning. 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

Are deprecated zones included?

Only the common, currently-active ones. Aliases like US/Eastern may still resolve, but we prefer canonical IDs.

Why does UTC+05:30 exist?

Some zones (India, Sri Lanka, Nepal at +05:45) use half- or quarter-hour offsets. They're real.

How is current time computed?

browser Intl.DateTimeFormat with timeZone option — no library.

Does DST affect offsets?

Yes — offsets are evaluated live, so DST regions tick on and off automatically.

Is anything sent to a server?

No. The search runs entirely in your browser.

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