Free UNIX Timestamp Converter — Epoch to Date, Batch Mode & Code Snippets
Convert any Unix timestamp to a human-readable date — or any date back to a timestamp. Supports seconds and milliseconds with auto-detection. Furthermore, natural language input lets you type "tomorrow" or "next Friday" and get the timestamp instantly. Batch mode converts up to 50 timestamps at once, and built-in code snippets show the conversion in Python, JavaScript, PHP, Bash and SQL.
How to use the UNIX Timestamp Converter
Unix timestamp formats and input types
Unix timestamps appear in three main formats across modern systems. Understanding the difference prevents the most common timestamp conversion errors. Furthermore, the Auto-detect unit option handles the most common formats correctly without any manual configuration.
| Format | Digits | Example | Used by |
|---|---|---|---|
| Seconds (Unix standard) | 10 | 1735689600 | Linux/Unix systems, POSIX APIs, most REST APIs |
| Milliseconds | 13 | 1735689600000 | JavaScript Date.now(), Java, Android, databases |
| Microseconds | 16 | 1735689600000000 | Python datetime.timestamp() × 1e6, InfluxDB |
Natural language input
Natural language input converts plain English date expressions into Unix timestamps instantly. Furthermore, supported phrases include: "today", "tomorrow", "yesterday", "next Monday", "next Friday", "in 7 days", "in 30 days", "3 days ago" and "10 days ago". This feature is particularly useful for quickly generating test timestamps for API development without manually calculating epoch values.
For more specific dates or times, enter a date string such as "2025-06-15" or "June 15 2025". Moreover, the tool parses standard date formats through JavaScript's native Date.parse function, which accepts most common international date formats.
What is a Unix timestamp and how is it calculated?
A Unix timestamp counts the number of seconds — or milliseconds — that have elapsed since the Unix Epoch: 1 January 1970 at 00:00:00 UTC. Furthermore, this reference point was chosen during the development of the Unix operating system in the early 1970s as a practical starting date that preceded any real-world production use of the system.
÷ 1000 = Converts milliseconds to seconds
UTC = All Unix timestamps are timezone-independent — always relative to UTC
Epoch = The reference point: 1 January 1970 00:00:00 UTC (timestamp 0)
The Year 2038 problem
32-bit systems store Unix timestamps as signed integers. The maximum value of a signed 32-bit integer — 2,147,483,647 — represents 03:14:07 UTC on 19 January 2038. Furthermore, any system using 32-bit timestamps will overflow on that date, rolling back to negative values representing 1901. Modern 64-bit systems extend this limit to the year 292,277,026,596, which effectively eliminates the practical concern. However, legacy embedded systems and old databases still risk the 2038 overflow without upgrades.
Worked example: debugging an API response
A developer receives a JSON API response containing a created_at field with the value 1700000000. When was this record created, and how long ago was it?
| Input | Value |
|---|---|
| Raw timestamp | 1700000000 |
| Digit count | 10 digits → auto-detected as seconds |
| Output format | Value |
|---|---|
| ISO 8601 UTC | 2023-11-14T22:13:20.000Z |
| UTC readable | Tue, 14 Nov 2023 22:13:20 GMT |
| Unix milliseconds | 1700000000000 |
| Relative time | ~18 months ago |
Batch conversion example
A data analyst receives an export file with 40 Unix timestamps in a created_at column. Furthermore, pasting all 40 values into Batch mode converts them simultaneously, saving the time of running 40 individual conversions. Each result includes the UTC date, local time and a relative label that shows at a glance how old each record is.
What is a Unix timestamp?
A Unix timestamp — also called an epoch timestamp or POSIX time — is a single integer that represents a specific moment in time as the number of seconds elapsed since 1 January 1970 at 00:00:00 UTC. Furthermore, because it is a single timezone-independent integer, every system in the world can represent the same moment with the same number, eliminating ambiguity across time zones.
Modern applications frequently use millisecond precision — multiplying the second-based timestamp by 1000. JavaScript's Date.now() returns milliseconds, while most Unix command-line tools and POSIX-compliant APIs return seconds. Moreover, some high-frequency systems use microseconds or nanoseconds, but these are less common in web-facing applications.
Where Unix timestamps appear in practice
Nearly every modern web API returns timestamps as Unix epoch values. Furthermore, REST APIs represent created_at and updated_at fields as integers. Furthermore, database systems including PostgreSQL, MySQL and MongoDB store datetime values internally as epoch offsets. Server logs and monitoring tools use Unix timestamps because they sort as plain integers. Furthermore, they need no timezone conversion for comparisons.
Why Unix timestamps are preferred in distributed systems
Distributed systems spanning multiple time zones benefit from shared UTC timestamps. Furthermore, integer comparison eliminates timezone ambiguity entirely. Additionally, integer comparison runs faster than datetime string comparison. As a result, epoch timestamps are preferred in high-throughput database queries. Moreover, Unix timestamps are immune to daylight saving time transitions. This removes a common source of bugs in regional datetime code.
Why Unix timestamp conversion matters for developers
API debugging is significantly faster when a developer can instantly read a timestamp in a JSON response. An opaque 10-digit number provides no immediate information about the data's age or validity. Furthermore, converting it to an ISO date string in under a second lets the developer immediately assess whether the record is current, stale or from an unexpected time period.
JWT token validation requires timestamp checking. JSON Web Tokens contain iat and exp fields as Unix timestamps. Moreover, converting these values quickly helps developers verify token windows without writing code.
How batch conversion speeds up data analysis
Data engineers working with exported database snapshots or analytics event logs routinely encounter columns full of Unix timestamps. Converting them one at a time is impractical at any meaningful scale. Furthermore, batch mode handles 50 timestamps simultaneously. Additionally, each result shows UTC dates and relative time labels for instant context.
Frequently asked questions
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