You have seen it in logs, databases, and JWTs: a number like 1754200000. That is a
Unix timestamp — and once you understand it, converting it becomes trivial. This guide shows how,
using the DevToolbox Timestamp Converter.
What is a Unix timestamp?
A Unix timestamp (or "epoch time") is the number of seconds since January 1, 1970, 00:00:00 UTC. It is a single, unambiguous number that does not depend on time zones or formatting conventions — which is exactly why servers and databases prefer it.
A brief history of the epoch
The "1970" start, called the Unix epoch, was chosen by early Unix engineers because it was a convenient recent round date. Decades later it became the universal baseline for timestamps across nearly every operating system and programming language.
Why systems love it
- Universal — one integer, no locale or daylight-saving ambiguity.
- Sortable — later moments are simply larger numbers.
- Efficient — cheap to store and compare.
- Portable — the same number means the same instant everywhere.
How to read a timestamp by hand
Take 1754200000. Divide by 86,400 (seconds per day) and you get roughly 20,304 days
since the epoch — about 55.6 years, landing in mid-2026. It is not something you compute mentally,
which is exactly why a converter helps; but the math shows why the number grows predictably.
Seconds vs milliseconds
Some systems (notably JavaScript Date.now()) use milliseconds.
If a timestamp looks ten digits too long, divide by 1,000. The converter shows both. Mixing the two
is a classic bug: a date set 1,000 times in the future.
Time zones, explained simply
The epoch is anchored to UTC. Your local time is UTC plus or minus an offset that may also shift
with daylight saving. A timestamp of 1754200000 is the same instant in New York and Tokyo;
only the displayed clock differs. Always record instants as epoch and convert for display.
Epoch in three environments
- Python —
datetime.fromtimestamp(1754200000)andtime.time(). - JavaScript —
new Date(1754200000 * 1000)(note the milliseconds). - SQL —
FROM_UNIXTIME(1754200000)in MySQL,to_timestamp()in Postgres.
Storing timestamps in databases
Prefer native TIMESTAMP or timestamptz columns over integer epoch when your
database supports them — they carry timezone semantics. But when exchanging data between services,
epoch integers remain the safest common language.
Converting epoch to a date
To read a timestamp, multiply by 1,000 to get milliseconds and feed it to a date function. The Timestamp Converter does this both ways:
- Paste the seconds into the "Unix timestamp" field.
- Click Convert to see UTC and your local time.
- Or pick a local date/time and click To Unix to get the epoch value.
- What about leap seconds?
- Unix time ignores leap seconds; it counts continuous seconds since the epoch. Most applications never need to worry about this.
- Does the converter need the internet?
- No. All conversion happens in your browser — nothing is sent anywhere.
- The year 2038 problem?
- 32-bit systems overflow on 19 January 2038. Modern 64-bit systems are unaffected; just avoid storing epochs in signed 32-bit integers.
Negative timestamps (before 1970)
Timestamps can be negative for dates before the epoch, such as -2208988800 for
1900-01-01. Most languages handle these correctly, but some naive parsers or spreadsheets choke on
them. If you work with historical data, test the boundary.
Converting between zones safely
Never "fix" a time by adding or subtracting a fixed offset yourself — daylight saving makes offsets change by date. Store epoch (zone-agnostic) and let a library convert to the viewer's zone at display time.
Timestamps in logs and tracing
Distributed systems stamp every event with epoch time so logs from different machines can be merged into one ordered timeline. Inconsistent clocks are the enemy here; that is why NTP synchronization matters.
Human-readable alternatives: ISO 8601
Sometimes you want a string a person can read, like 2026-08-03T12:00:00Z. ISO 8601
carries the same instant as an epoch but includes the zone, reducing ambiguity. Keep epoch for storage,
ISO for interchange with humans.
Displaying relative time
"3 hours ago" is friendlier than a raw number, but it is a display concern, not a storage one. Store the epoch, then compute the relative label at render time so it stays correct whenever the page refreshes.
Integer vs ISO in your database
Integers sort and compare fastest and avoid timezone ambiguity. ISO strings are more debuggable when read directly. Pick one convention per project and convert at the edges, not in the middle of your logic.
Epoch and HTTP caching
Cache headers like Expires and Last-Modified are expressed as epoch seconds.
Understanding the format helps you debug why a resource was served stale or re-fetched unnecessarily.
The 2038 bug, revisited
Systems storing epochs in a signed 32-bit integer overflow on 19 January 2038, wrapping to a negative number and breaking date math. If you maintain older software, audit for 32-bit time fields now — the fix is simply using 64-bit storage.