🛠️

Unix Timestamp Converter

Convert Unix timestamps to human-readable date/time and convert dates back to epoch format.

Mode

Enter Unix Timestamp

Unix Timestamp (seconds or milliseconds)

Quick Reference

Current Timestamp--

How It Works

Unix Timestamp = Number of seconds elapsed since January 1, 1970, 00:00:00 UTC (the Unix epoch)

To Date: Create a Date object from timestamp x 1000 (JavaScript uses milliseconds)

To Timestamp: Date.UTC(year, month-1, day, hours, minutes) / 1000

Milliseconds: Timestamp in seconds x 1000

Auto-detection: If the input exceeds 9,999,999,999, it is treated as milliseconds and divided by 1000

What Is a Unix Timestamp?

A Unix timestamp (also known as Unix time, POSIX time, or epoch time) is the number of seconds that have elapsed since January 1, 1970, at 00:00:00 Coordinated Universal Time (UTC). This moment is known as the Unix epoch. Unix timestamps provide a simple, unambiguous way to represent a specific moment in time as a single integer, making them the universal standard for recording time in computer systems, databases, APIs, and log files.

The Unix Epoch: Why January 1, 1970?

The choice of January 1, 1970, as the epoch was an early design decision by the creators of Unix at Bell Labs. The original Unix system stored time as a 32-bit signed integer counting seconds from the epoch. This was a practical choice that provided a simple, monotonically increasing counter that would be valid for decades. At the time of its creation in the early 1970s, the epoch was set to a recent, round date. The decision proved remarkably durable, and the Unix epoch is now used far beyond Unix systems, including Windows, web browsers, mobile operating systems, databases, and virtually every programming language.

The Year 2038 Problem (Y2K38)

The original 32-bit signed integer representation of Unix time can store values up to 2,147,483,647, which corresponds to January 19, 2038, at 03:14:07 UTC. After this moment, a 32-bit counter overflows and wraps to a negative number, representing a date in December 1901. This is known as the Y2K38 problem or the Unix Millennium Bug. Modern systems have largely mitigated this by using 64-bit integers for timestamps, which extends the range to approximately 292 billion years from the epoch. However, legacy embedded systems, older databases, and some file formats that still use 32-bit timestamps remain vulnerable.

Seconds vs. Milliseconds

The traditional Unix timestamp is measured in seconds. However, many modern systems, particularly JavaScript and Java, use millisecond-precision timestamps (the number of milliseconds since the epoch). A millisecond timestamp is simply the second-based timestamp multiplied by 1000. You can easily distinguish the two by length: a seconds timestamp is currently 10 digits (for example, 1700000000), while a milliseconds timestamp is 13 digits (for example, 1700000000000). This converter automatically detects which format you have entered and handles the conversion accordingly.

Unix Timestamps in Programming Languages

Every major programming language has built-in support for Unix timestamps. In JavaScript, Date.now() returns milliseconds and Math.floor(Date.now() / 1000) returns seconds. In Python, import time; time.time() returns seconds as a float. In PHP, time() returns seconds. In Java, System.currentTimeMillis() returns milliseconds. In C / C++, time(NULL) returns seconds. In Go, time.Now().Unix() returns seconds. In Ruby, Time.now.to_i returns seconds. In Rust, SystemTime::now().duration_since(UNIX_EPOCH) gives you the duration in seconds and nanoseconds. Understanding these differences is essential when working with APIs that may return timestamps in different precisions.

Common Date Formats Explained

ISO 8601 is the international standard for date and time representation (for example, 2024-01-15T10:30:00.000Z). The trailing Z indicates UTC. This format is unambiguous, sortable as a string, and the recommended format for APIs and data exchange. RFC 2822 is used in email headers and HTTP (for example, Mon, 15 Jan 2024 10:30:00 +0000). The US format uses month-first ordering (January 15, 2024), while the EU format uses day-first ordering (15/01/2024). When building software, always store and transmit dates as Unix timestamps or ISO 8601 strings, and convert to localized display formats only at the presentation layer.

Negative Timestamps

Unix timestamps can be negative, representing dates before the epoch. For example, a timestamp of -86400 represents December 31, 1969 (one day before the epoch). This is useful for historical data. However, not all systems handle negative timestamps correctly, so test thoroughly if your application needs to work with dates before 1970.

Loading interactive tool...

Share this tool

How to Use the Unix Timestamp Converter

1
Enter your values
Open the Unix Timestamp Converter and fill in the required input fields with your numbers or selections.
2
Review the calculation
The tool automatically computes the result as you type. Double-check your inputs to ensure accuracy.
3
Interpret your results
Review the calculated output along with any breakdowns, charts, or explanations provided to understand what the numbers mean for your situation.

Sources & Verification

MDN Web Docs ECMAScript Language Specification

Published by ConvertCrunch Editorial Team | Our Methodology

Frequently Asked Questions

What is the Unix Timestamp Converter?

The Unix Timestamp Converter is a free browser-based tool on ConvertCrunch. Convert Unix timestamps to human-readable date/time and convert dates back to epoch format. It requires no downloads, installations, or account signups. Simply enter your values and get instant, accurate results. The tool is designed for quick calculations and informed decision-making, whether you are a professional, student, or everyday user looking for reliable answers.

How do I use the Unix Timestamp Converter?

Using the Unix Timestamp Converter is straightforward. Enter your values into the input fields provided on the page, then calculate or adjust parameters to explore scenarios. Most processing happens locally in your browser. If a feature uses a third-party service, the tool identifies that connection and the privacy policy explains it. Most users get the answers they need in under a minute.

Is the Unix Timestamp Converter free to use?

Yes, the Unix Timestamp Converter is completely free to use with no account signup, email requirement, or premium tier. Most calculations run locally in your browser. Features that depend on live data or a third-party service require a network connection and are identified in the tool. You can use it as many times as you need for personal, educational, or professional purposes.

How accurate is the Unix Timestamp Converter?

The Unix Timestamp Converter uses standard algorithms, encoding specifications, and well-tested implementations. Output is deterministic and verifiable against official specifications. For encoding, hashing, and conversion tools, results match the relevant RFC or standard exactly. For estimation tools, results are based on industry benchmarks and may vary based on your specific environment and configuration.

Explore Related Resources

Go deeper with workflow guides, side-by-side comparisons, and reusable embeds connected to this tool.

Guides

Best Free Developer Tools & Utilities Online (2026)

Embed This Tool

Add this calculator to your website with a simple iframe.

Continue Through Topic Hubs

This tool is part of larger workflows. Open a hub to continue with the next relevant tools.

Conversion and Data Pipelines Hub

High-demand document, media, and data conversion flows for repeat utility usage.

file convertersdeveloper toolsreference tools

Related Tools

🛠️

Base64 Encoder / Decoder

Encode text to Base64 or decode Base64 strings instantly. Supports UTF-8 and file encoding.

🛠️

cURL Command Generator

Build cURL commands with headers, auth, query params, and body payloads for reliable API testing.

🛠️

Hash Generator

Generate SHA-1, SHA-256, SHA-384, and SHA-512 hashes from text or files. All hashing runs locally in your browser.

🛠️

Prompt Compression Tool

Compress verbose prompts into tighter instructions while preserving intent and reducing estimated token usage.

🛠️

Prompt Variant Generator

Generate multiple high-quality prompt rewrites from one base instruction to improve reliability, structure, and output style.

🛠️

SQL Query Formatter

Format messy SQL into readable clauses, normalize keyword casing, and produce compact minified queries.

🛠️

JSON Output Repair Tool

Repair common malformed JSON issues from AI outputs and return valid formatted JSON for downstream workflows.

🛠️

HTML Entity Encoder/Decoder

Encode special characters to HTML entities or decode entities back to readable text.