What is the Year 2038 problem?

Older 32-bit signed integer Unix timestamps overflow on January 19, 2038 at 03:14:07 UTC — the largest value a signed 32-bit integer can hold (2^31 − 1 seconds). After that, unpatched systems would see time wrap to 1901. Modern 64-bit systems and most updated software use 64-bit timestamps, pushing the overflow billions of years into the future.

Are Unix timestamps always in UTC?

Yes. Unix timestamps are timezone-agnostic — they represent a precise moment in time independent of location. You only apply a timezone when you display a timestamp as a human-readable date. This is exactly what makes Unix time so useful for systems that span timezones and for databases syncing across regions.

Why use Unix timestamps instead of ISO dates?

Simpler arithmetic (just integer subtraction for durations), universal compatibility across languages and systems, compact storage (a single number instead of a string), and no timezone or daylight-saving bugs during computation. For display purposes, convert to a human-readable format at the last possible moment.

How are leap seconds handled?

Unix time ignores leap seconds by convention — a day is always treated as exactly 86,400 seconds. POSIX systems either repeat a second or skip one during a leap second event to stay aligned. This means Unix time occasionally differs from true UTC by a few seconds, but only systems requiring astronomical precision care.

Why was January 1, 1970 chosen as the epoch?

It was a convenient round date chosen by Ken Thompson and Dennis Ritchie when designing Unix in the early 1970s. Originally, Unix counted 60ths of a second from 1971, but the system was soon redesigned to count seconds from 1970. There is no deeper significance — just a practical choice that stuck.

Can Unix timestamps go negative?

Yes — negative timestamps represent dates before January 1, 1970. For example, timestamp −86,400 corresponds to December 31, 1969 00:00:00 UTC. Most programming languages support negative Unix time, though some databases and APIs require dates to be from 1970 onward.

How do I get the current Unix timestamp?

In JavaScript: Math.floor(Date.now() / 1000). In Python: int(time.time()). In Unix/Linux shell: date +%s. On this page, the input field shows the current timestamp and updates live, so you can just read it directly.

Unix Timestamp Converter

Utility

Convert between Unix epoch timestamps and human-readable dates.

Utility

Unix Timestamp Converter

Generated on April 24, 2026

Timestamp → Date

Date → Timestamp

?What is the Unix Timestamp Converter?

A Unix timestamp is the number of seconds that have elapsed since January 1, 1970, at 00:00:00 UTC — known as the Unix epoch. It is the universal time format used by virtually every computer system, database, log file, and programming language for storing and comparing dates. This converter translates bidirectionally between Unix timestamps (in seconds or milliseconds) and human-readable dates in ISO, UTC, and local timezone formats. It is essential for developers debugging logs, analysts processing time-series data, and anyone who has ever received a large integer and wondered what date it represents.

The Formula

Timestamp (seconds) = (Date − Jan 1 1970 UTC) ÷ 1000 milliseconds. Date = Epoch + timestamp. Milliseconds version: timestamp × 1000 = ms since epoch.

Unix time counts seconds (or milliseconds in JavaScript and several APIs) since midnight on January 1, 1970 UTC. This epoch was chosen arbitrarily when the Unix operating system was being designed at Bell Labs. Because the timestamp is a plain integer, time arithmetic (duration, comparison, sorting) becomes trivial — subtracting two timestamps gives seconds elapsed, no timezone math required. This calculator auto-detects seconds vs milliseconds: values below 10^12 are treated as seconds, values above are treated as milliseconds.

Practical Examples

Unix timestamp 1700000000 equals November 14, 2023 at 22:13:20 UTC — a handy reference point for recent logs.

Timestamp 0 represents January 1, 1970 00:00:00 UTC — the beginning of Unix time and a common 'not set' sentinel value.

Timestamp 1609459200 equals January 1, 2021 00:00:00 UTC — useful when filtering for data since the start of 2021.

The current Unix timestamp changes every second; copy the running value when you need 'now' in an API call.

In JavaScript, Date.now() returns the current timestamp in milliseconds, which is the current second × 1,000 plus a few hundred extra milliseconds.

A log line with timestamp 1672531200 corresponds to January 1, 2023 00:00:00 UTC — making log analysis across timezones trivially consistent.

Frequently Asked Questions

Traditionally it is in seconds, which is the original C and Unix convention. JavaScript's Date.now() and many modern APIs use milliseconds to support higher precision. A simple rule: if the number is about 10 digits long, it's seconds; 13 digits long means milliseconds. This calculator auto-detects which one you entered.

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Unix Timestamp Converter

Unix Timestamp Converter

Timestamp → Date

Date → Timestamp

?What is the Unix Timestamp Converter?

The Formula

Practical Examples

Frequently Asked Questions

Is a Unix timestamp in seconds or milliseconds?

What is the Year 2038 problem?

Are Unix timestamps always in UTC?

Why use Unix timestamps instead of ISO dates?

How are leap seconds handled?

Why was January 1, 1970 chosen as the epoch?

Can Unix timestamps go negative?

How do I get the current Unix timestamp?

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