Timestamp Converter

Convert Unix timestamps to human-readable dates and back. Supports seconds, milliseconds, ISO 8601, and multiple timezones.

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Unix Timestamp → Human Date

Human Date → Unix Timestamp

Current Timestamp

Updates live every second

Common Use Cases

Inspect a JWT token's iat (issued at) or exp (expiry) claim by converting the numeric timestamp to a readable date to debug authentication issues
Convert a database record's created_at Unix timestamp to local time when analyzing logs or audit trails across different timezones
Generate the Unix timestamp for a specific future date and time to set a correct expiry, schedule, or deadline value in an API request
Quickly grab the current Unix timestamp in seconds or milliseconds to use as a cache-busting query parameter, a nonce value, or a 'now' reference in a script

About Timestamp Converter

Unix timestamps, also called epoch time, measure time as the number of seconds elapsed since January 1, 1970 at 00:00:00 UTC (the "Unix epoch"). This format is ubiquitous in software: database records, API responses, log files, JWT tokens, HTTP headers (like Last-Modified), and cryptographic signatures all express time as a Unix timestamp rather than a human-readable string, because numbers are unambiguous, timezone-agnostic, and trivially comparable.

There are two common variants: seconds (a 10-digit number like 1741618800) and milliseconds (a 13-digit number like 1741618800000). JavaScript's Date.now() always returns milliseconds. Most Unix/Linux system calls and POSIX APIs use seconds. Databases vary: PostgreSQL stores timestamps with microsecond precision while Redis typically uses seconds or milliseconds depending on the command. This tool auto-detects which unit you're using based on the magnitude of the value.

Converting between timestamps and human-readable dates is more subtle than it appears, because the same Unix timestamp represents different local times in different timezones. 1741618800 is 15:00 UTC, but that's 10:00 AM in New York (ET), 16:00 in Paris (CET), and 00:00 the following day in Tokyo (JST). For this reason, ISO 8601, the international standard format, always includes a timezone offset (like 2025-03-10T15:00:00Z for UTC, or 2025-03-10T10:00:00-05:00 for Eastern Time).

When building APIs, always store and transmit timestamps in UTC, and convert to the user's local timezone only at the presentation layer. This tool handles both directions: paste a Unix timestamp to see all its human-readable equivalents, or pick a date, time, and timezone to get the corresponding Unix value. Section 3 shows the current timestamp updating live every second, useful for quickly grabbing "right now" as a Unix value.

Frequently Asked Questions

What is a Unix timestamp?
A Unix timestamp is the number of seconds (or milliseconds) that have elapsed since January 1, 1970, 00:00:00 UTC, a moment known as the Unix epoch. It is timezone-independent: the same number means the same absolute instant in time everywhere in the world, making it ideal for storing and comparing times in databases, APIs, and distributed systems.
How do I tell if a timestamp is in seconds or milliseconds?
Count the digits. Current Unix time in seconds is around 1.74 billion (a 10-digit number), while the same time in milliseconds is around 1,741,000,000,000 (a 13-digit number). As a rule: if the value is 10 digits or fewer, it's seconds; if it's 13 digits or more, it's milliseconds. This tool auto-detects the unit and tells you which it assumed.
Why does the same timestamp show different times in different timezones?
A Unix timestamp represents an absolute moment in time: one fixed point on the timeline. But 'what time is it there?' depends on where you are. When you convert a timestamp to a human-readable date, you must choose a reference timezone. UTC is the universal reference; local time is UTC shifted by the timezone offset. New York (ET) is UTC-5 in winter and UTC-4 in summer, so the same Unix timestamp shows a different hour in New York versus London versus Tokyo.
What is ISO 8601 and why is it useful?
ISO 8601 is the international standard for representing dates and times. The format looks like 2025-03-10T15:45:00Z (UTC) or 2025-03-10T10:45:00-05:00 (with timezone offset). The Z suffix means UTC (Zulu time). ISO 8601 is unambiguous, sortable lexicographically, and universally understood by parsers across all programming languages, making it the best format for storing or transmitting timestamps in APIs and logs.
What does 'relative time' mean in the output?
Relative time expresses how far a timestamp is from right now in plain English, for example '2 hours ago', 'in 3 days', or '5 months ago'. It is useful for quickly understanding whether a timestamp is recent, current, or far in the past or future, without having to mentally compute the difference. The value updates each time you change the input.
How do I convert a JavaScript Date object to a Unix timestamp?
Use Date.now() to get the current time in milliseconds, or new Date().getTime() / 1000 to get seconds. To convert an existing Date object d to Unix seconds, use Math.floor(d.getTime() / 1000). To go the other way, from Unix seconds back to a Date object, use new Date(unixSeconds * 1000). This multiplication by 1000 is one of the most common sources of bugs when working with timestamps in JavaScript.

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