FIRST CH TOOLS LOCAL PROCESSING — NOTHING IS UPLOADED 日本語

FIRST CH TOOLS / 32 Unix Time Converter

Unix Timestamp Converter

Turn 1755999999 into a date — and a date back into a timestamp. Unix seconds, milliseconds, microseconds and nanoseconds all convert both ways against ISO 8601 and local time, with UTC and your time zone side by side and a relative reading such as 5 minutes ago. Paste a whole block of log lines to convert them all at once.

NOW — UNIX SECONDS
—
NOW — MILLISECONDS
—
NOW — ISO 8601 (UTC)
—
NOW — LOCAL TIME
—

Results

0
Converted
0
Not readable
—
Time zone
—
UTC offset

Paste timestamps or dates above — one per line — and the conversions appear here.

The table scrolls sideways. The TSV copy carries every field, including how each line was read and the UTC offset.

How to Use

  1. Paste a timestamp or a dateDrop in values pulled out of a log — 1755999999, 2026-08-24T09:30:00Z — one per line. However many lines you paste, they all convert at once.
  2. Pick the time zoneIt starts on the zone your device is set to. Switch to UTC when you are reading server logs, or to any IANA zone such as Asia/Tokyo to see the same instant where your users are.
  3. Read the row and copy itUnix seconds, milliseconds, ISO 8601 in UTC, local time and the relative reading sit side by side. Copy the whole table as TSV and paste it straight into a spreadsheet. Everything runs in your browser — nothing you type is uploaded.

About This Tool

The unit of a plain number is detected from its digit count. Up to 10 digits is read as Unix seconds, up to 13 as milliseconds, up to 16 as microseconds and anything longer as nanoseconds (Java and JavaScript hand you milliseconds; Python's time.time_ns() and Go's UnixNano() hand you nanoseconds). Set “Number unit” if you would rather say it outright. Digits below the millisecond are dropped, and the row says so. Negative values (before 1970) and fractional seconds such as 1755999999.123 work too.

Date strings are accepted in the shapes you actually paste. 2026-08-24T09:30:00Z (ISO 8601), 2026-08-24 18:30, 2026/8/24 9:05, the Japanese 2026年8月24日 18時30分, and Sun, 24 Aug 2026 03:00:00 GMT as it appears in HTTP headers. Type now for the current time. Quotes, brackets and trailing commas picked up from CSV or JSON are stripped for you.

A date with no offset is read as a local time in the selected zone. That is the single most common way to be an hour or nine out, so every such row is flagged. A wall-clock time that does not exist because of a daylight-saving jump (2:30 on the second Sunday in March in the US, say) is moved forward to the moment after the change, and flagged as well. If the input carries +09:00 or Z, that offset wins no matter which zone is selected.

An 8-digit number is a timestamp here, not a date. 20260824 as Unix seconds lands in August 1970, so reading it as a date would be badly wrong. Rows like that carry a warning — write the value as 2026-08-24 if you meant the date.

Relative readings (“just now”, “5 minutes ago”, “in 3 days”) are measured against the clock at the moment the page renders them. Up to 500 lines are converted at a time. Zone maths uses the Intl time zone database in your browser, so the results hold on daylight-saving transition days too.

You can share a value in the URL: /en/unixtime/?t=1755999999&tz=Asia/Tokyo (t takes several values separated by commas)

From AI Agents

This conversion logic is also available as the unixtime_convert tool of the MCP (Model Context Protocol) server @first-ch/tools-mcp, so an AI agent can call it directly without driving a browser. See How to use from AI agents for setup.

Install

claude mcp add firstch-tools -- npx -y @first-ch/tools-mcp

Calls

# Unix seconds in Tokyo local time
unixtime_convert(
  input="1755999999", timeZone="Asia/Tokyo")

# a block of lines lifted out of a log
unixtime_convert(
  input="1755999999\n2026-08-24T09:30:00Z\nnow",
  timeZone="UTC")

# say the unit outright instead of detecting it
unixtime_convert(
  input="1755999999123456", unit="us")

Other Tools