Example 1
- 1704067200
- mode sec
2024-01-01T00:00:00.000Z
What ISO at 1704067200 s? 2024-01-01T00:00:00.000Z. Frozen ISO from the JSON.
Unix Timestamp Converter
Type a stamp or ISO. 1704067200 s give 2024-01-01T00:00:00.000Z. 1711929600 give 2024-04-01T00:00:00.000Z. 2024-06-15T12:00:00Z stays 2024-06-15T12:00:00.000Z. Frozen ISO from the JSON.
Seconds × 1000 or ISO into Date, then toISOString. Extras freeze the JSON examples. IANA zones sit on Timezone converter.
Results
Enter data and click Calculate.
How it works
Unix Timestamp Converter in this calculator shows ISO UTC from the input. 1704067200 s give 2024-01-01T00:00:00.000Z. 1711929600 s give 2024-04-01T00:00:00.000Z. 2024-06-15T12:00:00Z stays 2024-06-15T12:00:00.000Z. Extras take frozen ISO from the JSON, not a clock.
Field ts-val is text. Select ts-mode stays sec in the examples. 1704067200 × 1000 is midnight 1 January 2024 UTC. 1711929600 is 1 April. The third extras pastes ISO and gets the same ISO with milliseconds.
2024-01-01T00:00:00.000Z is not Date.now. 2024-04-01 does not come from a Now button. 2024-06-15 does not use your zone in the result. You type the stamp.
Timezone converter next door counts UTC from an IANA date. Duration stacks hours. Here 1704067200 stays 2024-01-01T00:00:00.000Z.
Type 1704067200 and mode sec, then Calculate. The ISO is 2024-01-01T00:00:00.000Z. A blank field stops. This is not a live clock.
1704067200 gives 2024-01-01T00:00:00.000Z. 1711929600 gives 2024-04-01T00:00:00.000Z. 2024-06-15T12:00:00Z stays 2024-06-15T12:00:00.000Z.
Formula
ISO UTC = Date from seconds × 1000 or from pasted ISO. Extras freeze the JSON. Not a clock.
How to use
- Type 1704067200 and mode sec.
- Click Calculate. ISO is 2024-01-01T00:00:00.000Z.
- 1711929600 gives 2024-04-01T00:00:00.000Z. 2024-06-15T12:00:00Z stays 2024-06-15T12:00:00.000Z.
- Frozen ISO from the JSON, not a clock.
- IANA zones sit on Timezone converter.
1704067200 = 2024-01-01T00:00:00.000Z
Frozen ISO from the JSON. 1704067200 s give 2024-01-01T00:00:00.000Z.
- Unix
- Seconds from epoch. 2024-06-15T12:00:00Z returns 2024-06-15T12:00:00.000Z.
- Timestamp
- Field ts-val. 1704067200 leaves 2024-01-01T00:00:00.000Z.
- Converter
- Mode sec in extras. 1711929600 gives 2024-04-01T00:00:00.000Z.
Examples
Example 2
- 1711929600
- mode sec
2024-04-01T00:00:00.000Z
What ISO at 1711929600 s? 2024-04-01T00:00:00.000Z.
Example 3
- 2024-06-15T12:00:00Z
- mode sec
2024-06-15T12:00:00.000Z
What ISO at 2024-06-15T12:00:00Z? 2024-06-15T12:00:00.000Z.
Related calculators
Common questions
What ISO at 1704067200 s?
2024-01-01T00:00:00.000Z. Frozen ISO from the JSON, not a clock.
What ISO at 1711929600 s?
2024-04-01T00:00:00.000Z.
What ISO at 2024-06-15T12:00:00Z?
2024-06-15T12:00:00.000Z. Pasted ISO returns with .000Z.
Is this a live clock or a Now button?
No. Extras keep three frozen inputs from the JSON.
Does ms mode change 1704067200?
Yes. The examples keep sec. In ms the same number is another epoch.
Is the result local time?
No. The result is ISO UTC. The local row sits beside it.
Is 2024-01-01T00:00:00.000Z today?
No. It is 1704067200. There is no Date.now in extras.
Where do I convert Warsaw 12:00?
On Timezone converter. Here the ISO from 1704067200 stays.
Does a blank field count?
No. Without a stamp or ISO the calculator stops.
Knowledge sources
The calculator counts bits, bytes or throughput from your numbers. Below are SI and bit definitions (NIST).
Page updated in 2026.
The Unix epoch (1970)
A Unix timestamp is the number of seconds elapsed since 1970-01-01 00:00:00 UTC — a point called "the epoch." Dates before the epoch have negative values. It’s the simplest way to store time as a single number, independent of time zone or text format.
Timestamps in logs and APIs
- Server logs, message queues, and databases often store time as epoch — easy to sort, compare, and index.
- REST APIs return time as
created_at: 1700000000(seconds) or as ISO 8601 ("2023-11-14T22:13:20Z") — this calculator accepts both input formats. - JWTs use Unix seconds in the
iat,exp, andnbfclaims.
Digit length: seconds vs milliseconds
Mixing units is a common bug (JS Date.now() = ms; many APIs = seconds). Digit length is a quick sanity check.
| Digits | Usually means | Example |
|---|---|---|
| ~10 | seconds since epoch | 1700000000 |
| ~13 | milliseconds | 1700000000000 |
| ~16 | sometimes microseconds | 1700000000000000 |
Seconds vs milliseconds — a common pitfall
JavaScript’s Date.now() returns milliseconds, while many APIs and databases use seconds. Mixing up units produces a date off by thousands of years (treating seconds as milliseconds lands you back near 1970 plus a fraction of a day). Tell-tale sign: a seconds timestamp has about 10 digits (valid until ~2286); a milliseconds one has about 13.
UTC vs local time
A Unix timestamp has no time zone of its own — it always represents the same instant, regardless of where in the world you view it from. The "local time" in the result is that same instant interpreted through your device/browser’s time zone — a different user will see a different wall-clock time for the same timestamp.
Dates before 1970 (negative timestamps)
A timestamp can be negative — it represents a date before the epoch (e.g. -100000 is 1969-12-30). Most modern systems handle this correctly, but some older APIs and binary formats (e.g. 32-bit unsigned) cannot.
Examples
0(seconds) = 1970-01-01T00:00:00Z — the epoch itself.1700000000(seconds) = 2023-11-14T22:13:20Z.1700000000000(milliseconds) = the same instant — just a different unit.