Turn the long number computers use for time (a "Unix timestamp", or epoch time) into a normal date — and turn any date back into a timestamp. It shows your local time and UTC, and detects whether your number is in seconds or milliseconds.
About this Unix timestamp converter
A Unix timestamp (also known as epoch time) is the number of seconds since 1 January 1970, midnight UTC. It is how most computers, databases and programming languages store a moment in time as a single number. That is efficient for machines but unreadable for people — which is where this converter helps. Paste a timestamp and it shows the matching date in both UTC and your own local time zone. Type a date and it gives you the timestamp back, in seconds and milliseconds. It even detects whether the number you pasted is in seconds or milliseconds, a common source of bugs for developers. The live counter at the top shows the current timestamp ticking up second by second. Everything runs in your browser.
Frequently asked questions
- What is a Unix timestamp?
- The number of seconds since 1 January 1970 (UTC) — how computers store dates as one number.
- Seconds or milliseconds?
- Both are used. The tool detects which you pasted and converts it correctly.
- Which time zone?
- It shows your local time and UTC. Timestamps are always counted from UTC.
The Logic and Limits of Epoch Time
The core logic of Unix time relies on a linear count of seconds that ignores the complexities of the Earth's rotation. While UTC includes leap seconds to account for variations in planetary movement, the Unix convention treats every day as a fixed block of 86,400 seconds. This design choice simplifies calendar arithmetic, as the difference between two timestamps always equals the number of seconds elapsed between them. Consequently, the system is highly predictable for software, even if it requires manual adjustments to stay perfectly aligned with solar time.
Storage limits dictate how far into the future a system can track time. Legacy 32-bit signed integers reach their maximum capacity at 2,147,483,647, which corresponds to a specific moment in January 2038. Once this limit is exceeded, the integer overflows and reverts to its lowest possible negative value, effectively resetting the clock to late 1901. Transitioning to 64-bit integers resolves this constraint, providing a range that spans hundreds of billions of years.
Precision mismatches are the primary cause of bugs when integrating different programming environments. High-level languages like JavaScript and Java represent time in milliseconds, requiring a 13-digit integer to store current dates. In contrast, systems like C, Python, and PHP frequently use 10-digit integers to represent whole seconds. Mixing these units without conversion results in dates that appear to be either in the distant future or the 1970s, making it essential to verify the scale of the input data.