What Is a Unix Timestamp?
A Unix timestamp (also called Unix time, POSIX time, or epoch time) is a single integer representing the number of seconds that have elapsed since midnight on January 1, 1970, UTC. This moment is called the Unix epoch.
Right now, the Unix timestamp is approximately 1,746,000,000 (it grows by 1 every second). Negative numbers represent moments before 1970.
Why January 1, 1970?
When Unix was being developed at Bell Labs in the late 1960s, the team needed a universal reference point for representing time. 1970 was simply a round, recent date. The exact choice was partly practical: it put most dates the system would handle as small positive integers, which were efficient to store and compare.
There's nothing special about 1970 itself — it was a convention that became a standard because Unix became ubiquitous.
Why a Single Number Is Useful
**Timezone-agnostic.** A Unix timestamp represents a single, unambiguous moment in time. When you store a timestamp in a database and retrieve it in a different timezone, the timestamp doesn't change — only the human-readable conversion changes.
**Easy to compare.** Comparing two timestamps is a single integer comparison. Calculating the difference between two times is subtraction.
**Language-universal.** Every programming language has built-in functions to convert between timestamps and human-readable dates. A timestamp of 1714000000 means the same thing in Python, JavaScript, Go, and SQL.
**No ambiguity around DST.** Daylight saving time causes human-readable times to repeat (2:30 AM can occur twice in one day when clocks fall back). A timestamp has no such ambiguity.
Converting Timestamps
In JavaScript: new Date(1714000000 * 1000) — note the multiplication by 1000, because JavaScript's Date uses milliseconds while Unix timestamps use seconds.
In Python: datetime.fromtimestamp(1714000000)
In SQL: FROM_UNIXTIME(1714000000) (MySQL) or to_timestamp(1714000000) (PostgreSQL)
A common bug: forgetting the ×1000 in JavaScript. If a date shows as "January 1, 1970", you've passed seconds where milliseconds were expected.
The Year 2038 Problem
32-bit signed integers can store values up to 2,147,483,647. That's January 19, 2038 at 03:14:07 UTC. Systems that store Unix timestamps as 32-bit integers will overflow on that date, rolling over to a large negative number and interpreting it as December 13, 1901.
Modern 64-bit systems use 64-bit integers, which can store timestamps until approximately the year 292 billion — not an immediate concern. The 2038 problem affects legacy embedded systems and old software that hasn't been updated to use 64-bit time values.
Millisecond and Nanosecond Timestamps
Many modern APIs use millisecond timestamps (multiply by 1,000) or nanosecond timestamps (multiply by 1,000,000,000) for higher precision. JavaScript's Date.now() returns milliseconds. Go's time.Now().UnixNano() returns nanoseconds. Always check the units when working with a new API — an off-by-1000 error will make every date appear in 1970.
Working With Timestamps in Practice
NoxaKit's Unix Timestamp to Date converter handles both directions — paste a timestamp to see the human-readable date in your local timezone and UTC, or enter a date to get the corresponding timestamp. Useful when debugging API responses, log files, or database records that store dates as integers.