Epoch to Date Converter
Our free time converter handles epoch date conversions. See tables, ratios, and examples for quick reference. Includes formulas and worked examples.
Formula
Date = new Date(epoch * 1000)
Unix epoch time counts seconds since January 1, 1970 00:00:00 UTC. To convert to a date, multiply seconds by 1000 to get milliseconds (JavaScript standard). To convert a date back, divide the millisecond timestamp by 1000.
Worked Examples
Example 1: Convert Epoch to Date
Problem: What date does the epoch timestamp 1609459200 represent?
Solution: Multiply by 1000 to get milliseconds: 1609459200 x 1000 = 1609459200000\nCreate date: new Date(1609459200000)\nResult: January 1, 2021 00:00:00 UTC\nThis is midnight on New Year's Day 2021.
Result: 1609459200 = January 1, 2021 00:00:00 UTC
Example 2: Convert Date to Epoch
Problem: What is the epoch timestamp for July 4, 2025 at noon UTC?
Solution: Date: 2025-07-04T12:00:00Z\nCalculation: days from 1970-01-01 to 2025-07-04 = 20,273 days\n20273 x 86400 + 12 x 3600 = 1751623200 + 43200 = 1751630400\nOr use Date.UTC(2025, 6, 4, 12, 0, 0) / 1000
Result: July 4, 2025 12:00 UTC = 1751630400
Frequently Asked Questions
What is Unix epoch time?
Unix epoch time (also called POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970 at 00:00:00 UTC, not counting leap seconds. It is used by virtually all modern computer systems and programming languages as the standard way to track time. For example, the timestamp 1700000000 represents November 14, 2023 at 22:13:20 UTC.
What is the difference between epoch seconds and milliseconds?
Epoch seconds count whole seconds since January 1, 1970, while epoch milliseconds provide 1000 times more precision by counting thousandths of a second. Most Unix systems and languages like Python use seconds (10 digits, e.g., 1700000000), while JavaScript and Java use milliseconds (13 digits, e.g., 1700000000000). If your timestamp has 13 digits, it is in milliseconds.
Why does epoch time start on January 1, 1970?
The choice of January 1, 1970 as the epoch origin was made by early Unix developers at Bell Labs. It was a recent, round date that was easy to remember and provided a sufficiently large range for computing needs at the time. Using a fixed reference point simplifies time calculations across different time zones and systems, since all conversions are just arithmetic on a single integer value.
How do leap seconds affect epoch time?
Unix epoch time does not account for leap seconds. When a leap second is inserted by international timekeeping authorities, Unix time essentially repeats a second or adjusts gradually. This means Unix timestamps are not perfectly synchronized with astronomical time (UTC), but the difference is negligible for most applications. Since 1972, only 27 leap seconds have been added, so the maximum discrepancy is 27 seconds.
What formula does Epoch to Date Converter use?
The formula used is described in the Formula section on this page. It is based on widely accepted standards in the relevant field. If you need a specific reference or citation, the References section provides links to authoritative sources.
Can I use the results for professional or academic purposes?
You may use the results for reference and educational purposes. For professional reports, academic papers, or critical decisions, we recommend verifying outputs against peer-reviewed sources or consulting a qualified expert in the relevant field.