Unix Timestamp Converter

What is a Unix timestamp?

A Unix timestamp counts the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970 — called the Unix epoch. It is a single integer that uniquely identifies any moment in time regardless of timezone, making it the universal standard for storing timestamps in databases and APIs.

To convert a timestamp to a readable date, divide by 86400 to get days, then add to 1970-01-01. In practice, browsers and programming languages provide built-in functions that handle this. Negative timestamps represent dates before 1970.

How do I convert a Unix timestamp to a date?

To convert a Unix timestamp to a date, treat it as the number of seconds since 00:00:00 UTC on 1 January 1970 and add that many seconds to the epoch; to go the other way, subtract the epoch from a UTC date and count the elapsed seconds. Example: timestamp 1000000000 converts to 2001-09-09T01:46:40Z.

Steps to convert between timestamp and date

1. Take the Unix timestamp as a count of whole seconds elapsed since the epoch, 1970-01-01T00:00:00 UTC.
2. Multiply by 1000 if your programming environment expects milliseconds instead of seconds (JavaScript's Date object uses milliseconds).
3. Add that duration to the epoch instant to get the corresponding UTC date and time.
4. To convert a date back to a timestamp, express the date in UTC, subtract the epoch, and count the number of whole seconds between them.
5. Timestamps before 1970 are represented as negative numbers, counting seconds backward from the epoch.

Unix timestamp formula

• Epoch = 1970-01-01T00:00:00 UTC, the fixed reference point (timestamp 0)
• 86400 = number of seconds in one day, used to convert a day count to seconds and back

Example timestamp-to-date conversions (UTC)

Frequently asked questions

Why does the Unix timestamp use UTC instead of my local time?

Using a single UTC reference point avoids ambiguity from time zones and daylight saving time changes — a timestamp always refers to the same exact instant everywhere in the world, and each application converts it to the viewer's local time only for display.

What does a negative timestamp mean?

A negative timestamp represents a moment before the epoch, 1970-01-01T00:00:00 UTC. For example, -86400 means 86,400 seconds (one day) before the epoch, which is 1969-12-31T00:00:00 UTC.

Why do some systems use milliseconds instead of seconds?

The Unix timestamp standard is defined in seconds, but some languages and APIs (notably JavaScript's Date.now()) use milliseconds for finer precision. Multiply a seconds-based timestamp by 1000 to get milliseconds, or divide a milliseconds timestamp by 1000 to get seconds.

What happens to Unix timestamps after the year 2038?

Systems that store the timestamp as a signed 32-bit integer will overflow on 19 January 2038 at 03:14:07 UTC, a problem known as the Year 2038 issue. Most modern systems now use 64-bit integers for timestamps, which extends the usable range by billions of years and avoids this overflow.

This tool converts between Unix timestamps and calendar dates using the browser's built-in Date object; results depend on your device's clock and time zone settings for the local-time display, though the underlying timestamp and UTC value are always unambiguous.

Sources: POSIX / IEEE Std 1003.1 - Base Definitions (Seconds Since the Epoch)

Privacy and safety

• Runs in your browser — Everything you type is calculated on your own device. Your inputs are never sent to a utilduck server.
• Encrypted connection — Pages are served over HTTPS, so nobody on the network can read what you load.
• Not shared with third parties — Your inputs are not passed to analytics or advertising services.
• Nothing is stored — Results are not saved to any server, and there is no account to create.

Last updated: 2026-08-17