Unix Timestamp Converter

The Complete Guide to Unix Timestamps and Epoch Time

Every computer, server, database, and API that handles time relies on Unix timestamps. They power scheduling systems, log files, authentication tokens, financial transactions, and IoT devices worldwide. Yet despite their ubiquity, timestamps are one of the most common sources of bugs in software — particularly around time zones, milliseconds vs. seconds, and the looming Year 2038 problem. Our free Timestamp Converter lets you instantly convert between Unix epoch time and human-readable dates in both directions.

What is Unix Epoch Time?

Unix time (also called Epoch time, POSIX time, or Unix timestamp) is a system for describing a point in time as a single integer: the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC. This reference point is called the "Unix epoch."

Why January 1, 1970? When Unix was being developed in the early 1970s, the team needed a simple, universal reference point for time. They chose January 1, 1970 as it was recent and round. The exact time (midnight UTC) ensures it is time-zone neutral.

Key facts about Unix timestamps:

• The current Unix timestamp (as of 2024) is approximately 1,700,000,000+
• Unix timestamps are always in UTC — time zone conversion is the developer's responsibility
• Standard Unix timestamps count seconds (10-digit number)
• JavaScript and Java use milliseconds (13-digit number)
• Unix timestamps do NOT count leap seconds (they skip them)

Seconds vs. Milliseconds vs. Microseconds

One of the most common timestamp bugs occurs when mixing second-level and millisecond-level timestamps. The difference:

• Seconds (Unix standard): 1700000000 — 10 digits as of 2023
• Milliseconds (JavaScript Date.now()): 1700000000000 — 13 digits, multiply seconds by 1,000
• Microseconds (Python time.time_ns() / 1000): 1700000000000000 — 16 digits
• Nanoseconds: 1700000000000000000 — 19 digits

Our tool automatically detects seconds vs. milliseconds based on the number of digits, so you don't need to worry about which format you have.

The Year 2038 Problem (Y2K38)

The Year 2038 problem is the software equivalent of Y2K. On January 19, 2038 at 03:14:07 UTC, a 32-bit signed integer storing Unix seconds will overflow — wrapping around from its maximum value (2,147,483,647) to the minimum (-2,147,483,648). Systems that haven't been upgraded will think the date suddenly jumped back to December 13, 1901.

Affected systems include:

• Embedded systems with 32-bit processors (IoT devices, industrial controllers)
• Legacy databases using 32-bit INT columns for timestamps
• Old Unix/Linux systems on 32-bit architectures
• Some older file systems and backup systems

The solution is to use 64-bit signed integers, which can represent dates up to approximately 292 billion years in the future. Modern 64-bit operating systems and languages are already immune.

ISO 8601: The Universal Date Format

ISO 8601 is the international standard for representing dates and times in a machine-readable, sortable format. Our converter outputs ISO 8601 alongside the Unix timestamp:

• Date only: 2024-01-15 (YYYY-MM-DD)
• Date and time (local): 2024-01-15T10:30:00
• Date and time (UTC): 2024-01-15T10:30:00Z (Z = Zulu = UTC)
• With offset: 2024-01-15T16:00:00+05:30 (India Standard Time)

ISO 8601 is always preferred over locale-specific formats like "01/15/2024" (ambiguous — is it January 15 or the 1st day of the 15th month?) or "15-Jan-24" (language-dependent). Use ISO 8601 in APIs, log files, and any data that crosses time zones.

Common Timestamp Use Cases in Development

• API responses: REST APIs should return timestamps in ISO 8601 or Unix seconds. Never return locale-formatted date strings.
• Database storage: Store timestamps as UTC Unix integers or UTC datetime columns — never in local time.
• JWT expiration: JWTs use exp (expiration) and iat (issued at) claims as Unix timestamps in seconds.
• Logging: Log files should use UTC ISO 8601 timestamps to make correlation across servers and time zones possible.
• Cache control: HTTP headers like Last-Modified and Expires use RFC 7231 date format, which is convertible from Unix time.
• Cron jobs: Scheduling systems use Unix time internally to determine when the next job fires.

Use our free Timestamp Converter to instantly translate between Unix epoch and human-readable dates. For scheduling with cron expressions, also try our Cron Expression Generator.