Unix Timestamp Converter: Frequently Asked Questions

The Unix Epoch is the point in time from which Unix timestamps are counted: 00:00:00 UTC on Thursday, 1 January 1970. It was chosen when Unix was first developed as a convenient starting point. Timestamps before this date (negative timestamps) are valid and represent moments before January 1, 1970.

JavaScript: Math.floor(Date.now()/1000) (seconds) or Date.now() (ms). Python: import time; int(time.time()). PHP: time(). Ruby: Time.now.to_i. Go: time.Now().Unix(). Java: Instant.now().getEpochSecond(). Bash: date +%s. SQL (PostgreSQL): EXTRACT(EPOCH FROM NOW())::int.

You are likely passing seconds to a function that expects milliseconds. JavaScript's Date constructor expects milliseconds. Multiply your seconds timestamp by 1000: new Date(timestamp * 1000). A timestamp of 1700000000 in seconds = November 2023. The same value in milliseconds = January 1970 plus 1.7 million seconds ≈ January 20, 1970.

Unix time counts seconds from the epoch as a simple integer, with no concept of time zones, leap years, or calendar structure. UTC is a human-readable time standard (year, month, day, hour, minute, second) aligned with atomic time. Converting between them requires knowing the UTC offset for your timezone and accounting for leap seconds (which Unix time actually ignores).

Systems storing Unix timestamps as 32-bit signed integers can only represent values up to 2,147,483,647 — which corresponds to 03:14:07 UTC on 19 January 2038. After this point, the value overflows to a large negative number. Modern 64-bit systems are not affected, but legacy embedded systems and some older databases may be.

Yes. Negative Unix timestamps represent moments before the epoch. -1 is one second before midnight on January 1, 1970. -86400 is January 1, 1969. Most modern systems handle negative timestamps correctly, but some older software assumes timestamps are always positive.