How do I know if my timestamp is in seconds or milliseconds?

10-digit timestamps (e.g. 1718000000) are in seconds. 13-digit timestamps (e.g. 1718000000000) are in milliseconds.

Updated: August 2026 • Verified v1.2

Unix Timestamp Converter

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Convert Unix epoch timestamps (seconds & milliseconds) to human-readable dates (UTC, Local, ISO-8601, RFC 2822) and vice versa.

Local Browser Execution: Your input is processed locally in your browser and is not sent to UTL servers.

Epoch Milliseconds = Date.getTime(); Epoch Seconds = floor(Date.getTime() / 1000)

Understanding Your Results

Unix timestamp measures the continuous number of non-leap seconds elapsed since January 1, 1970 00:00:00 UTC. 10 digits = seconds; 13 digits = milliseconds.

Practical Guidance & Next Steps

Click 'Use Current Timestamp' to grab the current epoch time for testing JWT expiration dates (`exp`) or setting database created_at test values.

What is this?

A bi-directional time converter that translates between Unix epoch timestamps (seconds elapsed since January 1, 1970 UTC) and human calendar dates.

How does it work?

1. Paste a Unix epoch timestamp (10 digits for seconds, 13 digits for ms) OR select a calendar date. 2. Instantly see UTC date, local time, relative time ('3 hours ago'), and ISO-8601 format. 3. Click 'Current Time' to capture the exact live epoch timestamp.

Why use it?

Indispensable for debugging API payloads, database record timestamps, JWT expiration claims (`exp`), and log files.

Technical Scope & Calculation Limitations

32-bit signed integer timestamps will overflow on January 19, 2038 (the Year 2038 problem). This tool uses 64-bit JavaScript numbers and is immune to 2038 overflow.

Frequently Asked Questions

The Unix epoch is the moment 00:00:00 UTC on January 1, 1970. All Unix timestamps measure elapsed seconds or milliseconds from this fixed point in time.

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