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What Is a Unix Timestamp

A Unix Timestamp (Epoch Time) is the number of seconds elapsed since January 1, 1970, 00:00:00 UTC. It's a pure integer — for example:

• 1700000000 → November 14, 2023 22:13:20 UTC
• 1700000000000 → Same moment, but in milliseconds

Timestamps are the most common time representation in programming because they are timezone-agnostic, easy to store, compare, and calculate with.

Why You Need Timestamp Conversion

1. API debugging: Backend responses return timestamps that need human-readable conversion
2. Log analysis: System logs use timestamps that must be converted to local time
3. Database queries: SQL timestamp fields require conversion to dates
4. Cross-timezone collaboration: Timestamps provide a universal time baseline

How to Use an Online Timestamp Converter

Using DevToolkit Pro's Timestamp Converter:

1. Timestamp → Date: Paste a timestamp number; the tool auto-detects seconds/milliseconds/microseconds
2. Date → Timestamp: Select or enter a date-time, generate a timestamp instantly
3. Auto-detection: Paste any timestamp and the tool automatically determines the unit (s/ms/μs)

Timestamp Units Explained

| Unit | Digits | Example | Common Usage | |------|--------|---------|-------------| | Seconds (s) | 10 | 1700000000 | Unix/Linux, SQL, Redis | | Milliseconds (ms) | 13 | 1700000000000 | JavaScript, Java, Go | | Microseconds (μs) | 16 | 1700000000000000 | MySQL, high-precision timing |

Quick Identification

Count the digits to determine the unit:

• 10 digits → seconds (e.g., 1700000000)
• 13 digits → milliseconds (e.g., 1700000000000)
• 16 digits → microseconds (e.g., 1700000000000000)

Timestamps in Programming Languages

JavaScript / TypeScript

// Current timestamp (milliseconds)
const ms = Date.now();  // 1700000000000

// Current timestamp (seconds)
const s = Math.floor(Date.now() / 1000);  // 1700000000

// Milliseconds → Date object
const date = new Date(1700000000000);

// Date → milliseconds
const timestamp = date.getTime();

Python

import time
from datetime import datetime

# Current timestamp (seconds)
timestamp = int(time.time())

# Timestamp → datetime
dt = datetime.fromtimestamp(1700000000)

# datetime → timestamp
timestamp = int(dt.timestamp())

Go

import "time"

// Current timestamp (seconds)
timestamp := time.Now().Unix()

// Timestamp → Time
t := time.Unix(1700000000, 0)

Common Timestamp Pitfalls

Milliseconds vs. Seconds Confusion

The most common mistake. JavaScript's Date.now() returns milliseconds, while Unix standard is seconds. Passing a 13-digit millisecond timestamp to new Date() as seconds results in a date far in the future.

Timezone Issues

Timestamps are inherently UTC, but new Date().toLocaleString() uses the local timezone. For cross-timezone work, always anchor to UTC.

The Year 2038 Problem

A 32-bit signed integer maxes out at 2147483647, corresponding to January 19, 2038. At that point, 32-bit Unix timestamps will overflow. Modern systems have migrated to 64-bit timestamps, but embedded systems and legacy databases still need attention.

FAQ

Are Timestamps Timezone-Agnostic?

Yes. A Unix timestamp is the number of UTC seconds — it represents the same moment regardless of timezone. Timezone only matters when converting to a human-readable date string.

What Unit Does JavaScript's Date.now() Return?

Milliseconds (ms). This is the most common beginner mistake — treating a 13-digit millisecond timestamp as a 10-digit second-level timestamp.

How Do I Get the Current Timestamp?

In a browser console, type Date.now() (milliseconds) or Math.floor(Date.now()/1000) (seconds). You can also use DevToolkit Pro's online tool for one-click access.

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