Free Epoch Calculator
Convert between human-readable date/time and Unix epoch timestamp in seconds or milliseconds.
Date/Time → Epoch
Epoch → Date/Time
What Is an Epoch Timestamp?
An epoch timestamp (often called a Unix timestamp) is the number of seconds or milliseconds that have elapsed since January 1, 1970 at 00:00:00 UTC. This baseline point is known as the Unix epoch.
Computers and APIs use epoch values because they are compact, language-agnostic, and easy to compare. Instead of passing around long date strings, systems can pass a single integer.
Why You Might Need an Epoch Calculator
If you work with software logs, APIs, databases, analytics dashboards, or automation scripts, you will regularly encounter timestamps like 1700000000 or 1700000000000. An epoch calculator helps you quickly convert these values to meaningful date and time information.
- Debug app and server logs
- Validate API request/response payloads
- Convert frontend JavaScript dates for backend storage
- Check expiration times for tokens and sessions
- Schedule events with precise cross-timezone behavior
Seconds vs Milliseconds (The Most Common Mistake)
The most frequent timestamp bug comes from mixing units:
- Epoch seconds: 10 digits (example:
1700000000) - Epoch milliseconds: 13 digits (example:
1700000000000)
Many databases and backend services store seconds, while JavaScript Date.now() returns milliseconds. If you accidentally pass milliseconds where seconds are expected, your date can appear thousands of years in the future.
UTC vs Local Time
Use UTC for storage and transport
UTC avoids ambiguity from daylight saving transitions and regional offsets. For data exchange between systems, UTC should usually be your default.
Use local time for display
People read dates in local context. A product dashboard might store UTC internally, then display local time in the user interface.
Best Practices for Developers
- Store timestamps in UTC.
- Document whether your API uses seconds or milliseconds.
- Normalize user input at the application boundary.
- Test around DST changes and midnight boundaries.
- Prefer ISO 8601 for readability (
2026-02-16T14:30:00Z) alongside epoch where useful.
Quick FAQ
Can epoch timestamps be negative?
Yes. Dates before January 1, 1970 are represented as negative values.
Why does one tool show a different time than another?
Usually because one tool is showing UTC and the other is showing your local timezone. Always check timezone labels.
Should I save timestamps as integers or strings?
Use integers for efficient storage and sorting. Convert to formatted strings only when displaying to users.
Final Thoughts
A reliable epoch calculator saves time, prevents subtle date bugs, and improves confidence when integrating systems. Use the converter above whenever you need to go from timestamp to date (or back) quickly and accurately.