What is epoch time?
Epoch time (Unix time) counts the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970. The counter ignores leap seconds and keeps ticking even when your local region flips into daylight saving. Many APIs and logs expose raw epoch values because they are compact, timezone-neutral, and safe for arithmetic.
Systems vary on whether they use seconds or milliseconds. Node.js Date.now() returns milliseconds; POSIX tools
like date +%s emit seconds. Mixing them leads to values that are off by exactly 1,000, which is how
you end up thinking an event occurred in 51382 when it was really 2026.
Examples you will actually use
Example: Log correlation
You receive an alert referencing epoch 1771737600. Paste that value into the TimeyKit Epoch tool, choose “seconds,” and it resolves to March 24, 2026 00:00:00 UTC. Switch the output timezone dropdown to “America/Denver” to see it as March 23, 18:00 MDT. Copy the ISO 8601 representation (2026-03-24T00:00:00Z) straight into your incident timeline.
Example: API payloads
A webhook returns "expires_at": 1774513200000. The trailing three zeros signal milliseconds. Divide
by 1,000 or select “milliseconds” in the Epoch tool to convert. You will see it translates to April 24, 2026
05:00:00 UTC.
Going between epoch and ISO 8601
ISO 8601 strings look like 2026-02-22T18:45:00Z. The Z suffix means UTC. Localized
strings might include offsets such as +02:00. To convert ISO to epoch, parse the string in UTC, then
subtract the Unix epoch start. Modern browsers expose Date.parse(), but for repeatable workflows a
purpose-built tool is faster. Paste the ISO string into the Epoch converter, toggle “ISO → Epoch,” and the
seconds value appears instantly.
For multi-step date math, convert both timestamps to epoch seconds, subtract, then convert the difference back to a human-friendly format. This avoids confusion when one timestamp includes a daylight saving shift.
Best practices
- Store canonical timestamps in UTC.
- Document whether APIs expect seconds or milliseconds.
- When sharing data with humans, always include an ISO 8601 string alongside the raw number.
- When in doubt, test conversions using the Epoch tool before pushing to production.
Try the tool
The Epoch converter handles seconds, milliseconds, ISO 8601, and even relative deltas. Use it as a scratchpad next to your terminal.
FAQ
- Do leap seconds break epoch time?
- Unix time ignores leap seconds, so the difference between two timestamps stays integer-friendly. Most operating systems smear leap seconds gradually rather than pausing.
- What happens after 2038?
- 32-bit signed integers overflow at 03:14:07 UTC on 19 January 2038. Modern systems use 64-bit integers or store timestamps as floating-point numbers, so you are safe, but legacy embedded gear may need upgrades.
- Can I convert multiple timestamps at once?
- Yes—paste a comma-separated list into the Epoch tool’s batch mode or script it with your favorite language.