Unix Timestamp Converter

Why Unix Timestamps Exist

Time is surprisingly complicated. Timezones, daylight saving, leap years, leap seconds - human time measurement has countless edge cases. Unix timestamps sidestep all of it by counting seconds from a fixed moment: the Unix Epoch (January 1, 1970, 00:00:00 UTC).

This creates a universal reference that works identically everywhere. A timestamp of 1700000000 means the same instant in New York, Tokyo, and London. Converting to local time happens at display time, not storage time.

Seconds vs Milliseconds

Traditional Unix timestamps count seconds, producing 10-digit numbers (through 2286). JavaScript's Date.now() and many modern APIs use milliseconds, adding three more digits. The difference is whether you're at second or sub-second precision.

This converter auto-detects the format. If your number has more than 10 digits, it's treated as milliseconds and converted accordingly. You can input either format and get accurate results.

Common Timestamp Scenarios

Developers encounter timestamps constantly:

• JWT tokens - 'exp' and 'iat' claims are Unix timestamps
• API responses - Created/updated times often come as timestamps
• Database records - Many databases store dates as epoch time
• Log files - Events are frequently timestamped in epoch format
• Cron jobs - Scheduling often involves timestamp calculations
• Cache expiration - TTL values relative to current timestamp

The Year 2038 Problem

32-bit systems represent timestamps as signed integers with a maximum value of 2,147,483,647. This corresponds to January 19, 2038, at 03:14:07 UTC. One second later, the integer overflows and wraps to a large negative number - suddenly it's 1901.

Modern 64-bit systems use 64-bit timestamps, pushing this problem past the year 292 billion. If your software still runs on 32-bit timestamps, 2038 planning isn't optional - it's the next Y2K.

Working with Timezones

Unix timestamps are inherently UTC. The number itself has no timezone - it represents an absolute moment in time. When converting to human-readable format, you apply a timezone offset to display local time.

This page shows times in your browser's local timezone. If you need a timestamp for a specific timezone, convert the local time to UTC first, or adjust the displayed time by your target offset.

Timestamp Tips

When debugging, paste suspicious timestamps here to quickly verify they represent expected dates. A timestamp from 1970 usually means an uninitialized value. One from 2038+ on a 32-bit system might indicate overflow.

For testing, generate specific timestamps by entering dates. Need a token that expires in one hour? Enter that future time and grab the timestamp. Testing expiration logic becomes straightforward.