IBAN Validator

How IBAN Validation Works

The IBAN (International Bank Account Number) is an international standard (ISO 13616) for uniquely identifying bank accounts. Validation consists of three steps:

1. Format check — The code must start with 2 letters (ISO 3166-1 country code) followed by 2 check digits and the national BBAN code.
2. Length check — Each country has a specific IBAN length (e.g., Germany 22, UK 22, France 27). An IBAN with incorrect length is invalid.
3. MOD-97 check digit — The first 4 characters are moved to the end, letters are converted to numbers (A=10, B=11...Z=35), and the remainder when divided by 97 must equal 1.

This algorithm (ISO 7064) detects 99% of transcription errors, including adjacent digit transpositions. However, a mathematically valid IBAN may not correspond to a real account: validation only confirms formal correctness.

Anatomy of an IBAN: What Each Part Means

Every IBAN follows the same top-level structure, regardless of country. Let's break down a German IBAN as an example:

The first two letters always identify the country (DE for Germany, GB for UK, FR for France, IT for Italy). The next two digits are check digits that protect against typing errors. Everything after that is the BBAN (Basic Bank Account Number), whose internal structure varies by country:

• Germany (DE): 8-digit BLZ (bank routing code) + 10-digit account number
• United Kingdom (GB): 4-letter bank code + 6-digit sort code + 8-digit account number
• France (FR): 5-digit bank code + 5-digit branch code + 11-digit account number + 2-digit BBAN key
• Italy (IT): 1-letter CIN + 5-digit ABI (bank) + 5-digit CAB (branch) + 12-digit account number
• Spain (ES): 4-digit bank code + 4-digit branch code + 2-digit check digits + 10-digit account number
• Netherlands (NL): 4-letter bank code + 10-digit account number

MOD-97 Validation: Step-by-Step Example

Let's walk through the MOD-97 algorithm using a real UK IBAN: GB29 NWBK 6016 1331 9268 19

1. Remove spaces: GB29NWBK60161331926819
2. Move first 4 characters to the end: NWBK60161331926819GB29
3. Convert letters to numbers (A=10, B=11 ... Z=35):
   N=23, W=32, B=11, K=20, G=16, B=11
   Result: 23321120601613319268191629
4. Divide by 97: 23321120601613319268191629 mod 97 = 1
5. Remainder = 1? Yes → the IBAN is valid

If you change even a single digit — for example, swapping the "29" check digits to "28" — the remainder will no longer equal 1 and the IBAN will be detected as invalid. This is why MOD-97 catches 99% of transcription errors, including single-character substitutions and transposed adjacent digits.

IBAN vs SWIFT/BIC vs Routing Number

International banking uses several identification codes. Here's how they differ and when you need each one:

Key takeaway: For transfers within Europe (SEPA), you only need the IBAN. For transfers to non-SEPA countries, you typically need both the IBAN and the SWIFT/BIC code. The United States does not use IBAN; US transfers require an ABA routing number and account number instead.

IBAN Format by Country

Each country that uses IBAN has a fixed length and specific BBAN structure. Below is the complete list of all 79 countries supported by this validator, with example formats and IBAN lengths.

The complete list above includes all 79 countries that use the IBAN system: European SEPA zone (36 countries), Middle East (Saudi Arabia, UAE, Kuwait, Qatar, Bahrain, Jordan, Iraq, Israel, Palestine), North Africa (Egypt, Tunisia, Libya, Mauritania), Central and South America (Brazil, Costa Rica, El Salvador, Guatemala, Dominican Republic), and the Caribbean (Saint Lucia, British Virgin Islands, Seychelles, Mauritius, São Tomé).

IBAN by Region: Key Differences

Not all IBANs are created equal. Different regions have different IBAN lengths, structures, and banking systems. Here's what you need to know when sending money to each region:

Europe (SEPA Zone)

The 36 SEPA countries offer the fastest and cheapest cross-border transfers. Euro payments arrive in 1 business day at domestic rates. Key formats: Germany (DE, 22 chars) uses an 8-digit BLZ bank code, UK (GB, 22 chars) includes a 6-digit sort code, France (FR, 27 chars) has the longest Western European IBAN, and Norway (NO, 15 chars) has the shortest IBAN in the world. Post-Brexit, the UK remains part of SEPA for euro transfers.

Middle East

Saudi Arabia (SA, 24 chars), UAE (AE, 23 chars), Kuwait (KW, 30 chars), and Qatar (QA, 29 chars) all use IBAN for international transfers. These countries are outside SEPA, so transfers use the SWIFT network (3-5 business days, higher fees). Jordan has one of the longest IBANs at 30 characters.

North Africa

Egypt (EG, 29 chars), Tunisia (TN, 24 chars), Libya (LY, 25 chars), and Mauritania (MR, 27 chars) adopted IBAN to simplify international banking. Egypt's 29-character IBAN is among the longest in the system.

Americas & Caribbean

Brazil (BR, 29 chars) is the largest IBAN-using country in the Americas. Costa Rica, El Salvador, Guatemala, and the Dominican Republic also support IBAN. Note: the United States and Canada do NOT use IBAN — US transfers require an ABA routing number (9 digits) and account number instead.

Eastern Europe & Central Asia

Ukraine (UA, 29 chars), Georgia (GE, 22 chars), Kazakhstan (KZ, 20 chars), and Azerbaijan (AZ, 28 chars) use IBAN despite not being part of SEPA. Belarus uses a 28-character IBAN with both letters and digits in the BBAN section, making it one of the more complex formats.

When You Need to Validate an IBAN

Validating an IBAN before making a payment can save you from rejected transfer fees and delays. Here are the most common scenarios where IBAN validation is essential:

IBAN and the SEPA Area: What You Need to Know

The SEPA (Single Euro Payments Area) covers 36 European countries where euro transfers have the same conditions, fees, and processing times regardless of origin or destination. IBAN is the mandatory format for all SEPA payments.

SEPA countries: all 27 EU member states, plus Iceland, Liechtenstein, Norway, Switzerland, Monaco, San Marino, Vatican City, Andorra, and the United Kingdom. Overseas territories like Guadeloupe, Martinique, Réunion, and Mayotte are also part of SEPA.

SEPA vs international transfers: a SEPA euro transfer takes at most 1 business day and costs the same as a domestic transfer. A transfer to a non-SEPA country (e.g., USA, Japan) uses the SWIFT network and can take 3-5 days with higher fees.

Countries outside the EU like Saudi Arabia, Turkey, Brazil, Egypt, and Qatar also use the IBAN system for bank transfers, but they are not part of the SEPA area.

Common IBAN Mistakes and How to Avoid Them

Even a single wrong character makes an IBAN invalid. Here are the most frequent errors this validator helps you catch:

• Transposed digits — Writing "21" instead of "12" is the most common mistake. The MOD-97 check digit catches this 99% of the time.
• Letter/number confusion — O (letter) vs 0 (zero), I (letter) vs 1 (one), l (lowercase L) vs 1. Using the wrong character completely changes the checksum.
• Incomplete copy — Selecting the IBAN from a bank document without including the country code or last digits. Each country has a fixed IBAN length.
• Spaces in wrong positions — Spaces in IBANs are for readability only (every 4 characters). Some systems accept them, others don't. Our validator strips them automatically.
• Old or closed IBAN — An IBAN can be formally valid but refer to a closed account. Formal validation cannot verify this: you need confirmation from the bank.

What is an IBAN and why it matters

An IBAN (International Bank Account Number) is an internationally standardized alphanumeric code that uniquely identifies a bank account. Defined by ISO 13616, it’s used in over 80 countries to make money transfers safer and faster, both domestically and internationally.

Before IBANs, each country had its own bank account format: Italy used ABI+CAB+account number, Germany had BLZ+Kontonummer, France the RIB. This fragmentation caused frequent errors in cross-border transfers. The IBAN solved this by creating a single format recognized by every bank.

Today, IBANs are mandatory for all SEPA (Single Euro Payments Area) transfers and most international wire transfers. Without a valid IBAN, your payment will be rejected or delayed — costing you time and money.

Structure of an IBAN code

Every IBAN follows a precise structure made of four parts:

The total length varies by country: the UK uses 22 characters, Germany 22, France 27, Italy 27. The BBAN (Basic Bank Account Number, the part after the check digits) follows each country’s national banking rules.

How the check digit works (MOD-97)

The check digit is the heart of IBAN validation. It uses the MOD-97 algorithm (ISO 7064), which catches 98% of transcription errors, including swapping two adjacent digits.

1. Move the first 4 characters (country code + check digits) to the end
2. Convert all letters to numbers: A=10, B=11, C=12... Z=35
3. Calculate modulo 97 of the resulting number
4. If the result is 1, the IBAN is valid

This algorithm is remarkably effective: even a single wrong digit or letter will cause the modulo 97 check to fail. That’s why banks use it as the first filter before processing any transfer.

How to validate an IBAN step by step

Complete IBAN validation involves multiple levels of checking:

Level 1 — Format:

• The country code (first 2 letters) must be a valid ISO 3166-1 code
• The check digits (positions 3-4) must be two numeric digits
• The rest (BBAN) must contain only uppercase alphanumeric characters

Level 2 — Length:

• Each country has a fixed, specific IBAN length
• A UK IBAN must be exactly 22 characters, a German one 22, an Italian one 27

Level 3 — MOD-97 check digit:

• Apply the MOD-97 algorithm described above
• The result must be exactly 1

Level 4 — BBAN structure:

• Verify the BBAN follows the country-specific national format
• For the UK: 4 letters (bank code) + 6 digits (sort code) + 8 digits (account number)