Unix Timestamp
Epoch ↔ human date
About This Calculator
A Unix timestamp is the number of seconds that have elapsed since January 1, 1970, 00:00:00 UTC (the Unix epoch). It is the standard way computers represent moments in time — a single integer that is timezone-independent. Timestamps are used in databases, APIs, log files, and any system that needs to store or compare dates.
Formula
Unix timestamp = seconds since 1970-01-01 00:00:00 UTC
Human date → Unix: (date − epoch) in seconds
Unix → Human: epoch + timestamp seconds = date
Millisecond timestamps (JavaScript): Unix × 1000
Example Calculation
Convert March 16, 2026 12:00:00 UTC to Unix timestamp
- From 1970-01-01 to 2026-03-16 = 56 years
- 2026-03-16 12:00:00 UTC = Unix timestamp 1,773,403,200
Unix timestamp: 1,773,403,200 (approximately)
Notable Unix Timestamps
| Date | Unix Timestamp | Notes |
|---|---|---|
| 1970-01-01 00:00:00 UTC | 0 | Unix epoch |
| 2001-09-09 01:46:40 UTC | 1,000,000,000 | 1 billion seconds |
| 2009-02-13 23:31:30 UTC | 1,234,567,890 | Fun pattern |
| 2038-01-19 03:14:07 UTC | 2,147,483,647 | 32-bit overflow (Year 2038 problem) |
| 2106-02-07 06:28:15 UTC | 4,294,967,295 | 32-bit unsigned overflow |
Frequently Asked Questions
What is the Year 2038 problem?
Systems using 32-bit signed integers to store Unix timestamps will overflow on January 19, 2038 (when the count exceeds 2³¹−1 = 2,147,483,647). The value wraps to a large negative number, causing date calculation errors. Modern 64-bit systems store timestamps that won't overflow for ~292 billion years.
Why does JavaScript use milliseconds?
JavaScript's Date object measures time in milliseconds since the Unix epoch (to provide sub-second precision for interactive web applications). Always divide by 1,000 to convert JavaScript timestamps to standard Unix timestamps in seconds.
Is Unix time affected by leap seconds?
Officially, Unix time ignores leap seconds — it assumes every day has exactly 86,400 seconds. In practice, NTP servers handle leap seconds differently (smearing vs. stepping), causing brief discrepancies. For most applications this doesn't matter, but precision timing systems must account for it.
What timezone is a Unix timestamp in?
Unix timestamps are always UTC — they have no timezone. When displaying as a human-readable date, you convert from UTC to the desired timezone. This makes timestamps ideal for cross-timezone storage and comparison.