Regex for Unix timestamp (milliseconds)
13-digit Unix epoch in milliseconds.
The Unix timestamp (milliseconds) regex is ^\d{13}$ — copy it below, or open it in the explainer for a token-by-token breakdown.
The pattern
^\d{13}$
What it matches
17000000000001234567890123
What it doesn't match
170000000017000000000000
Notes & gotchas
13 digits — JavaScript Date.now() output. Will start having 14 digits in the year 5138.
Code in your language
Use the explainer's Code tab to generate ready-to-paste snippets in JavaScript, Python, Java, .NET, Go, Ruby, and PHP for this pattern.
Open in explainer →Token-by-token breakdown
Every part of the pattern, left to right:
| Token | Meaning |
|---|---|
^ | start of string (or line in multiline mode) |
\d{13} | exactly 13 times: digit (0–9) |
$ | end of string (or line in multiline mode) |
About this pattern
Date and time formats vary enormously across regions and systems. The regex here validates structure only — a date like 2024-02-30 would pass format validation but isn't a real date. After regex passes, parse with your language's date library to confirm semantic validity.
Quick usage in different languages
This exact pattern — with the correct escaping and idioms for each language:
- JavaScript:
/^\d{13}$/.test(value) - Python:
re.match(r"^\d{13}$", value) - Java:
Pattern.compile("^\\d{13}$").matcher(value).matches() - C# / .NET:
Regex.IsMatch(value, @"^\d{13}$") - Go:
regexp.MustCompile(`^\d{13}$`).MatchString(value) - Ruby:
/^\d{13}$/.match?(value) - PHP:
preg_match('~^\d{13}$~', $value)
The explainer’s Code tab regenerates these for any pattern you paste, and the downloadable cheat sheet bundles the breakdown, all seven snippets, and the pitfalls below onto one printable page.
Common pitfalls
- Anchored to the whole string. This pattern uses ^ and $, so it requires the entire input to match. To find it inside a longer text, drop the anchors and use the global (g) flag.
- Escape it correctly per language. In Java and JavaScript strings each backslash must be doubled (\\d); in Python, Go, and C# use raw/verbatim strings so the backslashes survive.
- Validate beyond format. Matching the format doesn't guarantee the value is real. Confirm the unix timestamp (milliseconds) against a source of truth (database, API, or checksum) where it matters.
Standards & sources
This pattern is based on the following authoritative specification(s) and issuing authorities. Formats can change — always confirm against the primary source.
Related patterns
More patterns in the Date & time category:
- Unix timestamp (seconds)
- RFC 2822 date
- ISO 8601 duration
- ISO 8601 week date
- Timezone offset
- Month name
See also
Browse all 300 patterns in the library, or open this regex in the interactive explainer to see a token-by-token breakdown, test against custom input, and generate code in seven languages.