Download Time Calculator
Estimate how long a file download will take based on file size and connection speed. Supports all common file size and speed units.
Unix Epoch Timestamp Converter
Convert Unix timestamps to human-readable dates and vice versa. Enter a timestamp or date components to get bidirectional conversion.
UTC Date⧉
2025-02-08
UTC Time⧉
00:00:00
Milliseconds⧉
1,738,972,800,000
Planning notes, formulas, and examples
About the Unix Epoch Timestamp Converter
The Unix Epoch Timestamp Converter translates between Unix timestamps (seconds since January 1, 1970 UTC) and human-readable date/time representations. Unix timestamps are the universal time format used in programming, databases, APIs, and system logs.
Every event in a computer system is ultimately recorded as a Unix timestamp: a single integer representing the number of seconds that have elapsed since the epoch (midnight UTC on January 1, 1970). While machines process these numbers efficiently, humans need readable dates and times.
This converter handles bidirectional conversion using pure mathematical algorithms. Enter a Unix timestamp to see the corresponding year, month, day, hour, minute, and second in UTC. Or enter date components to generate the Unix timestamp. It also provides millisecond timestamps used by JavaScript and other platforms.
When This Page Helps
Developers, system administrators, and data analysts encounter Unix timestamps daily in logs, databases, APIs, and configuration files. This converter translates between machine-readable timestamps and human-readable dates without requiring a programming environment or browser console.
How to Use the Inputs
- Enter a Unix timestamp (seconds since epoch) in the input field.
- The calculator shows the corresponding UTC date and time.
- Alternatively, enter year, month, day, hour, minute, second to get the timestamp.
- View the millisecond timestamp for JavaScript compatibility.
- Results are always in UTC (Coordinated Universal Time).
Formula used
From timestamp to date: Decompose total seconds into years, months, days, hours, minutes, seconds using modular arithmetic and the Gregorian calendar rules.
From date to timestamp: Sum the total days from epoch to the given date, multiply by 86,400, and add the time-of-day seconds.
Milliseconds = Unix Timestamp × 1,000Example Calculation
Result: 2000-01-01 00:00:00 UTC
The Unix timestamp 946684800 represents January 1, 2000 at midnight UTC. This is calculated by counting the total seconds from January 1, 1970 00:00:00 UTC to that date, which equals 946,684,800 seconds.
Tips & Best Practices
- The current Unix timestamp increases by 1 every second.
- JavaScript uses millisecond timestamps (multiply Unix by 1,000).
- Negative timestamps represent dates before January 1, 1970.
- The Year 2038 problem affects 32-bit systems that overflow at timestamp 2,147,483,647.
- Always store and transmit timestamps in UTC to avoid time zone issues.
- Common test value: timestamp 0 = January 1, 1970 00:00:00 UTC.
Unix Time in Software Development
Virtually all programming languages provide functions to get the current Unix timestamp, and databases store timestamps internally as integers or similar numeric types. REST APIs commonly use Unix timestamps in request and response payloads for event times, expiration dates, and scheduling.
Converting Without Libraries
The algorithm to convert a timestamp to a date involves repeated division: divide by 86,400 to get total days, then decompose days into years (accounting for leap years), months, and remaining days. The reverse process sums up all the days from epoch to the target date.
Best Practices
Always store timestamps in UTC and convert to local time only at the display layer. This avoids DST-related bugs and makes it easy to compare events across time zones. When exchanging timestamps between systems, document whether you use seconds or milliseconds to prevent off-by-a-factor-of-1000 errors.
Sources & Methodology
Last updated:
Frequently Asked Questions
A Unix timestamp (also called epoch time or POSIX time) is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC. It provides a universal, timezone-independent way to represent any point in time as a single number.
The Unix epoch is the reference point: January 1, 1970 at 00:00:00 UTC. All Unix timestamps are measured as seconds since this moment. The epoch was chosen as a convenient starting point when Unix was being developed at Bell Labs in the early 1970s.
On January 19, 2038 at 03:14:07 UTC, the Unix timestamp reaches 2,147,483,647—the maximum value for a signed 32-bit integer. Systems using 32-bit time will overflow. Most modern systems now use 64-bit integers, which won't overflow for billions of years.
Yes. Negative Unix timestamps represent dates before January 1, 1970. For example, timestamp −1 represents December 31, 1969 at 23:59:59 UTC. Many systems support negative timestamps for historical dates.
Unix timestamps are useful because they are timezone-independent, easy to compare (just compare two numbers), easy to do arithmetic with (add seconds for duration), and compact (a single integer). They avoid the complexity of calendar math.
Unix traditionally uses seconds since epoch. JavaScript and some APIs use milliseconds (seconds × 1,000). A seconds timestamp like 1700000000 becomes 1700000000000 in milliseconds. Always check which format an API expects.
More in this topic
Daylight Saving Time Checker
Check DST rules by region and year. See when clocks spring forward and fall back, plus the UTC offset used during each daylight saving period.
ISO 8601 Date Formatter
Format any date and time as an ISO 8601 string. Enter year, month, day, hour, minute, second and get the properly formatted ISO date string.