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Date & Time Studio — Unix Timestamp & Time Zone Converter

Paste a Unix timestamp or almost any date string — the unit and format are detected automatically and shown in 15 formats and multiple time zones. DST gaps, month ends and Japanese era boundaries are handled precisely.

On-device・No upload

Your files and input are processed only inside your browser on this device and are never uploaded to our servers.

Current time · UTC--:--:--—
Unix time (seconds)—

How to use

  1. Pick a base time zone at the top (your device’s zone by default). The current time and Unix time update live.

  2. Enter a timestamp or date in the converter. Seconds, milliseconds, microseconds and nanoseconds are detected from the digit count, and ISO 8601, RFC 2822, month-name and other formats are recognized automatically.

  3. Copy any output format with one click, choose another zone to display, or add zones to the world clock.

  4. Use “Duration” for the difference between two dates, “Add / subtract” for date arithmetic, and “Japanese era” for Reiwa/Heisei conversions.

What it does

Automatic unit and format detection

Timestamps are classified by digit count — seconds (10), milliseconds (13), microseconds (16) or nanoseconds (19) — and nanoseconds are kept exact. ISO 8601, RFC 2822, HTTP-date, JavaScript Date strings, month names, ISO week dates and more are parsed.

15 output formats

ISO 8601 (with offset, UTC and basic), RFC 2822, HTTP-date, SQL DATETIME, Unix time in four units, ISO week date, ordinal date, Excel serial number and Japanese formats — each one click to copy — plus a custom token-based pattern.

Correct DST handling

Offsets come from your browser’s IANA time zone database. Local times that do not exist (spring forward) or occur twice (fall back) are detected and the chosen interpretation is explained. Compare several zones side by side.

Durations and date arithmetic

Differences are shown as years, months, days, hours, minutes and seconds plus totals and weekdays. Adding months clamps to month end (Jan 31 + 1 month = Feb 29/28) and adding days keeps the local clock time across DST.

Japanese era conversion

Converts between Gregorian dates and the Meiji, Taisho, Showa, Heisei and Reiwa eras with day-exact boundaries, and rejects impossible dates such as Showa 64-01-08 with the correct answer.

Use cases

  • Turn epoch values from logs or databases (1700000000, 1700000000123) into readable dates
  • Produce ISO 8601 / RFC 3339 strings for APIs, or HTTP-date headers
  • Schedule a meeting across New York, London and Tokyo with correct DST
  • Count the days, weeks or weekdays between two dates
  • Find the date 90 days or 3 months from a given day

Capability matrix

FeatureSupportNotes
Unix time in s / ms / μs / ns (auto-detected)Supported—
ISO 8601 / RFC 3339 / RFC 2822 / SQL parsingSupported—
IANA time zones and DSTSupportedUses the time zone data in your browser
Durations and add / subtractSupported—
Japanese era ⇔ GregorianPartialFrom the start of Meiji (23 Oct 1868); pre-1873 lunisolar dates are not converted
Business days excluding public holidaysNot supportedOnly weekends are excluded
Leap secondsNot supported23:59:60 is treated as :59, as in Unix time
Natural language (“next Monday”)Not supported—
Offline useSupportedWorks without a connection once loaded

Limits & notes

  • Dates are limited to JavaScript’s range (about 270,000 years either side of 1970).
  • Ambiguous inputs like 01/02/2024 are read as month/day/year, and the tool says so.
  • Time zone rules come from your browser and may not include very recent government changes.
  • Weekday counts exclude Saturdays and Sundays only.

Privacy & safety

All parsing and calculations run in your browser; nothing you enter is sent to or stored on a server. The current time comes from your device clock — no external time server is contacted.

FAQ

What is a Unix timestamp?
The number of seconds since 1 January 1970 00:00:00 UTC. JavaScript and Java often use milliseconds (13 digits) and some systems use microseconds or nanoseconds; this tool detects the unit from the number of digits.
How do I tell seconds from milliseconds?
Current timestamps have 10 digits in seconds and 13 in milliseconds — 1700000000 and 1700000000000 are the same moment (14 Nov 2023 22:13:20 UTC). 16 digits means microseconds, 19 nanoseconds.
How does the tool handle daylight saving time?
“1 day later” keeps the same local clock time, while “24 hours later” adds exact elapsed time, so they differ by an hour across a DST change. Times that do not exist or occur twice are flagged with the interpretation used.
What is the difference between ISO 8601 and RFC 3339?
RFC 3339 is a stricter profile of ISO 8601 for internet use, always with date, time and offset, e.g. 2024-01-15T10:30:00+09:00. The “ISO 8601 / RFC 3339 (with offset)” output satisfies both.
How are ISO week numbers calculated?
Weeks start on Monday and week 1 contains the year’s first Thursday, so early January can belong to the previous year’s week 52 or 53 (e.g. 3 Jan 2021 is 2020-W53-7).
Is anything sent to a server?
No. Everything runs locally in your browser, including the live clock.

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