How does the tool tell seconds from milliseconds?

By magnitude. Values below ~1e11 are treated as seconds (Unix epoch seconds through ~5138 AD), values above as milliseconds. This covers nearly all real-world timestamps. The detected mode is shown below the input.

What timezone is used for the 'Now' button?

The current moment is universal; 'Now' just inserts the current epoch value. The timezone only affects how the timestamp is displayed in the 'In selected timezone' field — the underlying instant is the same.

Why is my date showing as 'Invalid'?

The input couldn't be parsed. Browsers accept ISO 8601 ('2024-01-15T10:00:00Z'), RFC 2822, and most common formats. Ambiguous formats like '01/02/2024' (which month?) are interpreter-specific — prefer ISO 8601 for reliability.

Is this accurate for historical dates or leap seconds?

JavaScript's Date object ignores leap seconds and uses the proleptic Gregorian calendar. Accurate for most practical use cases (1970-2100 business timestamps) but not suitable for astronomical or pre-1582 historical precision.

Timestamp Converter

Paste a Unix timestamp (seconds or milliseconds), an ISO 8601 string, or any date-string your browser can parse — get all the other formats back instantly. Pick a timezone from common IANA zones plus your browser default. See relative time ('3 hours ago') against the current moment, which ticks live. Runs 100% in the browser with no network call.

Now:starting live clock...

Input (Unix seconds, milliseconds, ISO 8601, or date string)10 / 100,000

Timezone

Detected as: Unix seconds

Relative

in 0 seconds

Unix seconds

Unix milliseconds

ISO 8601 (UTC)

In selected timezone (UTC)

UTC (RFC 2822)

Frequently Asked Questions

How does the tool tell seconds from milliseconds?: By magnitude. Values below ~1e11 are treated as seconds (Unix epoch seconds through ~5138 AD), values above as milliseconds. This covers nearly all real-world timestamps. The detected mode is shown below the input.
What timezone is used for the 'Now' button?: The current moment is universal; 'Now' just inserts the current epoch value. The timezone only affects how the timestamp is displayed in the 'In selected timezone' field — the underlying instant is the same.
Why is my date showing as 'Invalid'?: The input couldn't be parsed. Browsers accept ISO 8601 ('2024-01-15T10:00:00Z'), RFC 2822, and most common formats. Ambiguous formats like '01/02/2024' (which month?) are interpreter-specific — prefer ISO 8601 for reliability.
Is this accurate for historical dates or leap seconds?: JavaScript's Date object ignores leap seconds and uses the proleptic Gregorian calendar. Accurate for most practical use cases (1970-2100 business timestamps) but not suitable for astronomical or pre-1582 historical precision.

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About Timestamp Converter

Convert between Unix epoch (seconds/ms), ISO 8601, and human-readable dates. Timezone picker, relative time, and 'Now' buttons included. This tool runs entirely in your browser, so your content is not sent to a server. MarkdownMe provides free, fast, and reliable Markdown tools for developers, writers, and anyone who works with Markdown.