Epoch in, four formats out

A Unix timestamp converter that returns every format at once

Paste an epoch value — Unix seconds or milliseconds — or an ISO 8601 string, press Enter, and read the same instant as UTC ISO 8601, Unix seconds, Unix milliseconds, and your local system time. The Timestamp tab of CodePrettify’s Data Converter runs entirely on your device.

Install for ChromeRead the manual section
  • Seconds and milliseconds auto-detected
  • ISO 8601 with Z or ±HH:MM
  • Negative and fractional values
  • Local processing
CodePrettify Data Converter utilities with the Timestamp tab for Unix timestamp conversion beside Convert, Hash and HMAC, and ID Generator
The Data Converter keeps Convert, Hash & HMAC, Timestamp, and ID Generator utilities together in one dialog.
Conversion example

Unix time to date — one input, four answers

Most timestamp questions are really four questions: what is this instant in UTC, in epoch seconds, in epoch milliseconds, and on my own clock? One conversion answers all of them.

Epoch input

A bare number from a log line

The value is below 100,000,000,000, so auto-detection reads it as Unix seconds. No format picking, no guessing which log used which unit.

1786699800
Converted result

The same instant in every representation

UTC for correctness, epoch values for code and queries, local time for reading it as a human.

UTC ISO 8601       2026-08-14T09:30:00Z
Unix seconds       1786699800
Unix milliseconds  1786699800000
Local time         2026-08-14 11:30  (example: UTC+02:00)
1

Paste or use now

Enter any epoch or ISO 8601 value, or press Use current time to fill the present moment in milliseconds.

2

Press Enter

Enter converts directly on the Timestamp tab — no mouse trip to a button.

3

Read all four outputs

UTC ISO 8601, Unix seconds, Unix milliseconds, and local system time appear together.

Timestamps from private systems stay private.

Conversion runs locally in the extension launcher, in any viewer tab, or in the Windows app. Epoch values copied from production logs, tokens, or database rows are never uploaded to a web service.

Hands-on tutorial

Convert epoch seconds, milliseconds, and ISO 8601 in one session

Seven short exercises cover the whole Timestamp tab, including the edge cases — negative values, fractions, and strings that deserve rejection.

  1. Open the Timestamp tab

    Open Data Converter from More Actions or the Command Palette in a viewer tab, from Tools in the Windows app, or directly from the extension launcher. The dialog has four tabs — Convert, Hash & HMAC, Timestamp, and ID Generator — and the arrow keys cycle between them.

  2. Convert a Unix-seconds value

    Paste 1786699800 and press Enter. Because the absolute value is below 100,000,000,000, it is treated as seconds. Confirm the UTC result reads 2026-08-14T09:30:00Z and that the local-time line matches your system clock’s timezone.

  3. Convert the same instant in milliseconds

    Now paste 1786699800000. The value exceeds the detection boundary, so it is read as milliseconds — and every output matches the previous step. This is the fastest way to confirm which unit a log or API actually uses.

  4. Convert an ISO 8601 string with an offset

    Paste 2026-08-14T11:30:00+02:00 and press Enter. The explicit +02:00 offset makes the instant unambiguous, so the UTC output is again 09:30:00Z. A trailing Z works the same way, and ISO seconds and fractions (up to nine digits) are optional.

  5. See why a zoneless string is refused

    Try 2026-08-14 11:30 without any timezone. The converter rejects it rather than silently assuming UTC or your local zone — a wrong assumption here shifts every derived value by hours. Add Z or an explicit ±HH:MM offset and retry.

  6. Capture the current moment

    Press Use current time. The input fills with the present moment in milliseconds; press Enter to expand it into all four representations. Handy when you need “now” as an epoch value for a query or a token expiry check.

  7. Exercise the edge cases deliberately

    Convert -86400 — negative pre-1970 values are accepted, and it resolves to 1969-12-31T00:00:00Z. Convert 1786699800.5 — fractional Unix values are accepted, and the half second appears in the millisecond output. For far-future dates or early-epoch millisecond values, choose the unit explicitly instead of relying on auto-detection.

Timestamp sanity checklist

Before pasting a converted value into code, a query, or a bug report, confirm these points.

  • The detected unit — seconds or milliseconds — matches what the source system emits.
  • Every ISO 8601 input carried Z or an explicit UTC offset.
  • The milliseconds output is exactly 1,000 times the seconds output.
  • The local-time line matches the timezone your system is actually set to.
  • Far-future or early-epoch values were converted with an explicitly chosen unit.
Inputs and outputs

What the epoch converter accepts and what it returns

Unix input

  • Unix seconds
  • Unix milliseconds
  • Negative pre-1970 values
  • Fractional values

ISO 8601 input

  • Z for UTC
  • Explicit ±HH:MM offsets
  • Seconds optional
  • Fractions up to nine digits

Automatic unit detection

  • Below 100,000,000,000 → seconds
  • Larger → milliseconds
  • Explicit unit choice available
  • Needed for far-future and early-epoch cases

Four outputs per conversion

  • UTC ISO 8601
  • Unix seconds
  • Unix milliseconds
  • Local system time

Current time in one click

Use current time fills the present moment in milliseconds — a quick source for “now” when writing queries or checking expiries.

Keyboard flow

  • Enter converts on the Timestamp tab
  • Arrow keys cycle the four tabs
  • No mouse required for repeat conversions

Strict and local

  • Zoneless date strings rejected, never assumed
  • Overall range ±8,640,000,000,000,000 ms
  • Runs on your device — no upload
Detection rules

How the converter interprets what you paste

Auto-detection covers the common cases; the table shows where it applies and where an explicit unit choice is the safer move.

What you enterHow it is interpretedWhy
1786699800Unix seconds → 2026-08-14T09:30:00ZAbsolute value below 100,000,000,000 is treated as seconds.
1786699800000Unix milliseconds → the same instantValues above the boundary are treated as milliseconds.
-86400One day before the epoch → 1969-12-31T00:00:00ZNegative pre-1970 values are accepted.
1786699800.5Fractional seconds → the half second lands in the millisecond outputFractional Unix values are accepted.
86400000 meant as millisecondsAuto-detected as seconds — choose the unit explicitlyEarly-epoch millisecond values fall below the detection boundary.
2026-08-14T11:30:00+02:00ISO 8601 with an explicit offset → 09:30:00ZThe offset makes the instant unambiguous.
2026-08-14 11:30RejectedNo timezone — add Z or a ±HH:MM offset instead of letting a tool guess.
Beyond the dialog

Timestamps stay readable across CodePrettify

The Timestamp tab is the precise instrument, but epoch values show up everywhere — so the rest of the toolset helps too.

CodePrettify Data Converter dialog showing operation controls, input and output panes, and the four utility tabs
Data Converter in the viewer — the Timestamp tab sits one arrow-key press away from Convert, Hash & HMAC, and ID Generator.
1

Hover hints in the JSON viewer

Structured JSON adds human-readable timestamp hints for integer Unix values dated 2000–2050 and for ISO-like strings — you often read the date without opening the converter at all.

2

Time-ordered IDs next door

The ID Generator tab creates UUID v7 and ULID values that embed the current Unix-millisecond timestamp, so generated identifiers sort by creation time.

3

Same tool in both products

The Data Converter behaves identically in the browser extension and the Windows app, so one set of habits covers both.

FAQ

Unix timestamp conversion questions

How does the converter decide between seconds and milliseconds?

Auto-detection treats absolute values below 100,000,000,000 as Unix seconds and larger values as milliseconds, so everyday timestamps sort themselves out. Choose the unit explicitly for far-future dates or early-epoch millisecond values, where magnitude alone cannot tell the two apart.

Why was my date string rejected?

A date string without a timezone is ambiguous — 2026-08-14 11:30 names a different instant in every region. The Timestamp tab rejects such strings instead of silently assuming a zone. Add Z for UTC or an explicit offset such as +02:00 and it converts.

Does the Unix timestamp converter work offline?

Yes. Conversion runs entirely on your device — in the extension launcher, in any viewer tab, or in the Windows app. Nothing is uploaded, so timestamps from private logs and tokens never leave your machine.

What outputs does a conversion produce?

Every conversion returns the same four results: UTC ISO 8601, Unix seconds, Unix milliseconds, and the time in your system’s local timezone. Convert once and read whichever representation the destination needs.

Related guides

JSON Formatter and Viewer

Inspect API responses with folding and diagnostics — epoch values dated 2000–2050 get readable hover hints inline.

Explore the JSON viewer →

HTTP Client Browser Extension

Send requests and read the timestamped responses, headers, and tokens the converter helps you decode.

Explore the HTTP client →

Data Converter Manual

Review every tab — Convert, Hash & HMAC, Timestamp, ID Generator — with controls, shortcuts, and limits.

Open the manual →

Stop pasting production timestamps into random websites

Convert epoch seconds, milliseconds, and ISO 8601 on your own device — four outputs per conversion, Enter to convert, nothing uploaded.

Install for ChromeSee $0 early access