Unix Timestamp Converter

Paste an epoch timestamp, or pick a date, time and timezone. Everything is converted on your device — nothing is sent anywhere.

ISO 8601 (UTC)
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ISO 8601 (selected zone)
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RFC 2822 (UTC)
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Locale string
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Relative
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Seconds
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Milliseconds
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Now: —

Epoch time, in one place

A Unix timestamp is just a running count of time since midnight UTC on 1 January 1970. Because it is a single number tied to UTC, it means the same moment on every machine — no timezone attached, no ambiguity. That is why logs, databases and APIs lean on it. The catch is that it is unreadable at a glance, and half the ecosystem counts seconds while the other half counts milliseconds.

Seconds or milliseconds

This converter decides by magnitude. A ten-digit number like 1,700,000,000 is seconds (November 2023); a thirteen-digit number like 1,700,000,000,000 is milliseconds. The threshold sits at 1012, which as a seconds count would land tens of thousands of years in the future — so a number that large can only be milliseconds. The detected unit is spelled out under the field so you are never guessing.

Both directions

Leave the timestamp box empty and the date-and-time field takes over: pick a wall-clock time and a zone, and the seconds and milliseconds rows show that instant's epoch value. The zone list is your browser's own — the same database that powers Intl — so the offsets, including past and future daylight-saving rules, are as good as the platform has.

Related

Working with tokens that carry iat and exptimestamps? Decode them with thehash generator's neighbour tools, or hash a payload for a cache key here. For a plain span between two dates rather than an instant, use the percentage calculator for ratios or theword counter for text stats — all of them, like this one, run entirely in the page.

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Frequently asked questions

What is a Unix timestamp?
A count of the time elapsed since 1970-01-01 00:00:00 UTC — the Unix epoch. Most systems count in seconds; JavaScript, Java and many APIs count in milliseconds. The number is always UTC-based, so it means the same instant everywhere.
How does it know seconds from milliseconds?
By size. Anything from 1,000,000,000,000 upward is treated as milliseconds — that value is the year 33658 if read as seconds, so it can only be a millisecond count. Smaller values are read as seconds. The detected unit is shown under the input.
Why does the date not match my local clock?
The ISO (UTC) line is the instant in UTC. The second ISO line and the locale line are the same instant shown in the timezone you selected. Pick your own zone from the list to see your wall-clock time.
What formats does it output?
ISO 8601 in UTC and in your chosen zone, an RFC 2822 / HTTP-style UTC string, a full locale string, a relative phrase like “3 days ago”, and the raw seconds and milliseconds.
Can I go from a date back to a timestamp?
Yes. Fill in the date-and-time field and choose a timezone; the seconds and milliseconds rows update to that instant's epoch value. Leave the timestamp field empty so it does not take priority.
How accurate is the timezone conversion around daylight saving?
The zone list and offsets come from your browser's own timezone database, which knows historical and future DST rules. The one soft spot is the single ambiguous hour that repeats or is skipped at a DST switch, where the result can be an hour out.
Is the ticking “now” line doing anything network-related?
No. It is your device clock, read once a second with a timer that is cleared when you leave the page. Nothing about your time or timezone is transmitted.

Last reviewed: September 2026. Figures and formulas are checked against their published sources; see the site's data notes.