Pattern

Regex for IBAN

International Bank Account Number — 15 to 34 alphanumeric chars.

The pattern

^[A-Z]{2}\d{2}[A-Z0-9]{1,30}$

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What it matches

GB29NWBK60161331926819
DE89370400440532013000
FR1420041010050500013M02606

What it doesn't match

GB29 NWBK 6016 1331 9268 19
12NWBK60161331926819
GB29

Notes & gotchas

Format: 2-letter country + 2-digit check + up to 30 alphanumerics. Total length varies by country (e.g., 22 for UK, 22 for Germany, 27 for France). Strip spaces before matching. Run the mod-97 check in code for full validation.

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.

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About this pattern

European Union identifiers follow standards set by individual member states with EU-wide coordination (VAT VIES, IBAN/SEPA, etc.). The regex validates structure; for production use, validate via the appropriate registry.

Quick usage in different languages

Once you've validated a candidate value matches this pattern, you'll typically use it inside your application code. Each language has its own regex syntax:

JavaScript: new RegExp(pattern).test(value)
Python: re.match(pattern, value) with raw strings: r"pattern"
Java: Pattern.compile(pattern).matcher(value).matches()
C# / .NET: Regex.IsMatch(value, pattern)
Go: regexp.MustCompile(pattern).MatchString(value) — Go uses RE2 so some advanced features aren't available
Ruby: value =~ /pattern/ or pattern.match?(value)
PHP: preg_match('/pattern/', $value)

The explainer's Code tab generates these for any pattern you paste — including the right escaping and idioms for each language.

Common pitfalls

Anchors matter. If the pattern uses ^ and $ it expects the entire input to match. To find this pattern inside a longer text, remove the anchors and use the /g flag.
Case sensitivity. Letter ranges like [A-Z] only match uppercase. Use the i flag or [A-Za-z] for case-insensitive matching.
Escape user input. If you're building a regex from a string variable, escape regex metacharacters first to avoid bugs or injection.
Performance. For this specific pattern the risk is low, but be cautious of nested quantifiers when adapting it — they can cause exponential backtracking on adversarial input.