Utilities & Converters

Unix Timestamp Converter

Epoch seconds and milliseconds to dates, in any zone.

What it does. A Unix timestamp counts seconds since 1 January 1970 UTC. JavaScript uses milliseconds instead, which is the most common source of confusion — a value around 1.7 billion is seconds, and around 1.7 trillion is milliseconds.

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How to use Unix Timestamp Converter

Paste a timestamp or pick a date.
The unit is detected from the magnitude.
Read it in UTC, your local zone or any other.

Seconds or milliseconds

Unix time is seconds. JavaScript’s Date.now() returns milliseconds. Most other languages return seconds.

The tell is length: a current timestamp in seconds is 10 digits, in milliseconds 13. Passing milliseconds to something expecting seconds produces a date around the year 55,000 — which is at least obviously wrong.

The dangerous direction is the other one. Passing seconds where milliseconds are expected gives a date in January 1970, which looks like a missing value rather than a unit error and is often silently treated as one.

Why 1970

It is arbitrary. Unix engineers chose the start of 1970 as a convenient recent epoch when the convention was established in the early 1970s.

Other systems chose differently: Windows file times count 100-nanosecond intervals from 1601, and several databases use their own epochs.

That is why timestamps are not portable between systems without knowing the epoch and the unit. A raw integer is meaningless without both.

The 2038 problem

A signed 32-bit integer holding seconds overflows on 19 January 2038, wrapping to a negative number and producing a date in 1901.

This is not hypothetical — it is the same class of bug as Y2K, and it affects embedded systems, older file formats and any code still using a 32-bit time_t.

Modern 64-bit systems are unaffected for a period longer than the age of the universe. The remaining exposure is in embedded devices, long-lived file formats and databases with 32-bit timestamp columns, which is a real and unglamorous migration still under way.

Frequently asked questions

Is my timestamp in seconds or milliseconds?

Count the digits. A current timestamp is 10 digits in seconds and 13 in milliseconds. JavaScript uses milliseconds; most other languages use seconds.

Why did my date come out as 1970?

Seconds were passed where milliseconds were expected. That is the dangerous direction, because a 1970 date looks like a missing value rather than a unit error and often gets treated as one.

Why does Unix time start in 1970?

It is arbitrary — a convenient recent epoch when the convention was set in the early 1970s. Windows file times count from 1601, and several databases use their own epochs.

What is the 2038 problem?

A signed 32-bit seconds counter overflows on 19 January 2038 and wraps to 1901. 64-bit systems are unaffected; the remaining exposure is embedded devices, old file formats and 32-bit database columns.

Do timestamps include time zone?

No. Unix time is always UTC — it is a count of seconds, not a local time. The zone is applied only when you format it for display.