This online calculator transforms human-readable calendar dates and times into precise Unix Timestamps. While humans organize time using years, months, and days, computer systems, databases, and APIs rely on a continuous integer count known as “Epoch Time.” This tool allows developers to input a specific future or past date and instantly generate the corresponding machine-readable code in both seconds (standard) and milliseconds (JavaScript/Java).
// Enter a date below. Select "Local" or "UTC", or choose a specific timezone from the list.
How to Use This Calculator
This widget features a modular, digital input system designed for precision. Follow these steps to generate your timestamp:
- Enter Date Parameters: Input the numerical values for Year, Month, and Day in the top row of fields.
- Enter Time Parameters: Input the Hour (0-23 format), Minute, Second, and Millisecond. If left empty, these default to zero.
- Select Timezone Mode: Use the toggle switch to define how the tool interprets your input. Choose Treat as Local Time to calculate based on your computer’s current timezone, or Treat as UTC for absolute Coordinated Universal Time.
- Generate: Click the Get Timestamp button. The tool will output the result in two formats simultaneously: Seconds and Milliseconds.
- Copy Data: Click the clipboard icon next to either result to copy that specific value.
Definitions of Time Inputs
The Gregorian Date (Human Time)
This tool accepts dates based on the Gregorian calendar, the international standard. It requires specific components (YYYY-MM-DD) and a 24-hour clock format (HH:MM:SS). Converting these variable components (where months have different lengths and years have leap days) into a linear integer is the primary function of this converter.
Timezone Sensitivity
The most critical factor in converting a date to a timestamp is the timezone. “January 1st, 00:00” happens at different moments depending on where you are on Earth.
- Local Mode: The tool assumes the date you entered is relative to your current location (e.g., if you are in New York, it applies the EST/EDT offset).
- UTC Mode: The tool treats the input as “Zulu Time” (zero offset), which is the standard for server logs and international data exchange.
Conversion Formula
Converting a Gregorian date to a Unix Timestamp involves calculating the total number of seconds that have passed between the Unix Epoch (1970-01-01 00:00:00 UTC) and the target date. This algorithm must account for every leap year, the varying number of days in each month, and the precise time of day.
The Logic: Timestamp = (Total Days since 1970 × 86,400) + (Hours × 3600) + (Minutes × 60) + Seconds
This calculation assumes UTC. If Local Time is used, the result is adjusted by adding or subtracting the timezone offset (in seconds) specific to that date.
Source: The algorithms for time conversion are formally defined in POSIX.1-2017 Standard (Base Definitions).
Date to Timestamp Conversion Table (UTC)
| Target Date (UTC) | Unix Timestamp (Seconds) |
|---|---|
| 1970-01-01 00:00:00 | 0 |
| 1980-01-01 00:00:00 | 315532800 |
| 1990-01-01 00:00:00 | 631152000 |
| 2000-01-01 00:00:00 | 946684800 |
| 2010-01-01 00:00:00 | 1262304000 |
| 2020-01-01 00:00:00 | 1577836800 |
| 2023-01-01 00:00:00 | 1672531200 |
| 2024-01-01 00:00:00 | 1704067200 |
| 2025-01-01 00:00:00 | 1735689600 |
| 2026-01-01 00:00:00 | 1767225600 |
| 2027-01-01 00:00:00 | 1798761600 |
| 2028-01-01 00:00:00 | 1830297600 |
| 2029-01-01 00:00:00 | 1861920000 |
| 2030-01-01 00:00:00 | 1893456000 |
| 2038-01-19 03:14:07 | 2147483647 |
Real World Use Cases
Why do we need to convert readable dates back into these long integers? Here are 10 common scenarios where this conversion is required:
- Database Filtering: Writing SQL queries to select rows created after a specific date (e.g., `WHERE created_at > 1704067200`).
- API Parameters: Sending a request to an API for data within a specific time range (e.g., `?start=1672531200&end=1704067200`).
- Cookie Expiration: Setting a browser cookie to expire exactly one year from today.
- Cron Jobs: Scheduling a server task to run at a specific future moment.
- License Keys: Generating a software license that becomes invalid after a specific date.
- Countdown Timers: Calculating the remaining seconds until a product launch or event.
- Caching Headers: Setting HTTP headers (`Expires`) to control how long content is stored by browsers.
- File Systems: Manually modifying the “Last Modified” attribute of a file using command-line tools like `touch`.
- Digital Certificates: Defining the “Not Before” and “Not After” validity periods for SSL/TLS certificates.
- Testing: Mocking time in unit tests to verify how software behaves during leap years or year rollovers.
We hope this tool simplifies your development workflow. Do you use this calculator for setting API parameters, database management, or system administration? If there are other time-related utilities you would like to see, please let us know in the comments section below.
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