Unix Timestamp Guide

The Unix epoch is midnight UTC on January 1, 1970: 1970-01-01T00:00:00Z in ISO 8601 notation. A Unix timestamp counts the number of seconds that have elapsed since that moment. June 15, 2026 at midnight UTC is approximately 1750032000.

Timestamps are always in UTC. They do not carry timezone information. When you see a timestamp, it represents the same instant everywhere on Earth—the local clock reading will differ by timezone, but the underlying moment is the same.

Timestamps sort correctly as integers. A later moment always has a larger timestamp. This makes them ideal for sorting events, measuring durations, and storing instants in databases where you need deterministic ordering.

The name Unix timestamp reflects the origin: the convention was established in Unix operating systems in the late 1960s and early 1970s and has since been adopted by almost every programming language and platform.

Original Unix timestamps count seconds. A ten-digit integer like 1750032000 is a second-precision timestamp. Many modern systems—JavaScript in particular—count milliseconds instead. A thirteen-digit integer like 1750032000000 is a millisecond-precision timestamp representing the same moment.

The simplest heuristic: if the timestamp is ten digits, it is seconds. If it is thirteen digits, it is milliseconds. Divide a millisecond timestamp by 1000 to get the equivalent second value.

Mixing seconds and milliseconds in one system is a common bug. A timestamp of 1750032000000 fed into a function that expects seconds will produce a date in the year 57000-something—an obvious signal that you have the wrong precision. The reverse produces a date in 1970, near the epoch.

JavaScript's Date.now() returns milliseconds. Python's time.time() returns seconds as a float. Database TIMESTAMP columns often store seconds. Always confirm the precision of a timestamp before converting or comparing.

To convert a timestamp to a human-readable date, paste it into the Unix Timestamp Converter on DateToolsHQ. The tool accepts both second and millisecond timestamps and displays the UTC date and time in ISO 8601 and long-form formats.

To convert a date to a timestamp, enter the date and time in the converter. The tool outputs the Unix second timestamp for that UTC moment. Use this when your system requires a timestamp and you have a calendar date.

In programming, timestamp conversion is a one-liner in most languages. In Python: datetime.utcfromtimestamp(ts). In JavaScript: new Date(ts * 1000) for second timestamps or new Date(ts) for millisecond timestamps. The Unix Timestamp Converter is useful for quick checks without writing code.

For date math on timestamps—how many days between two timestamps, or what date is 30 days after a timestamp—convert both to dates first, then use the Days Between Dates or Add/Subtract Days calculator.

Timestamps before the Unix epoch—January 1, 1970—are negative. December 31, 1969 at midnight UTC has timestamp −86400. Systems that store negative timestamps correctly can represent any date in the Gregorian calendar, though very early dates (before around 1678 or after 9999) may exceed the range of some 64-bit implementations.

Some older or embedded systems use 32-bit signed integers for timestamps. The maximum 32-bit signed value (2,147,483,647) corresponds to January 19, 2038 at 03:14:07 UTC—the Year 2038 problem. Modern systems use 64-bit integers which extend the range by billions of years.

The Unix Timestamp Converter accepts negative values for dates before 1970. For typical business date calculations, negative timestamps are uncommon—most date questions involve dates after 1970.

A timestamp has no timezone. It represents an instant in UTC. When you display a timestamp to a user, your application must convert that UTC instant to the user's local timezone. The same timestamp appears as different clock readings in New York, London, and Tokyo.

Timestamp 1750032000 is midnight UTC on approximately June 15, 2026. In New York (UTC−4 during daylight saving), it is 8 PM on June 14. In Tokyo (UTC+9), it is 9 AM on June 15. The underlying instant is identical; only the local representation differs.

Use the Timezone Converter to see how a UTC datetime appears in another timezone. When you need to share a specific moment across timezones—a meeting time, a deadline, a server event—timestamps or explicit UTC notation (2026-06-15T00:00:00Z) are the safest representations.

Storing timestamps in UTC and converting to local time at display is the standard pattern in web development. Storing local times without timezone information is a common source of bugs when users or servers are in different timezones.

The Days Until Calculator counts calendar days to any future date—or how many days ago a past date was—with an optional include-today setting for planning.

Countdown To Date adds an optional UTC time, event name, and hour/minute updates when you need more detail than calendar days alone.

Seasonal pages target the next occurrence automatically: Valentine's Day (February 14), Mother's Day (second Sunday in May), Independence Day (July 4), Halloween (October 31), Thanksgiving (fourth Thursday in November), Black Friday (the following Friday), Cyber Monday (the Monday after Thanksgiving), Easter Sunday (Gregorian), Christmas (December 25), and New Year's Day (January 1).

For a live second-by-second display with hours and minutes, use the Countdown Timer when the target includes a specific time of day in UTC.