IBAN Validator
Calculate IBAN Validator step by step: Move the first four characters to the end, convert letters to numbers (A=10 … Z=35), then the number mod 97 must equal 1.
In short
Formula: Move the first four characters to the end, convert letters to numbers (A=10 … Z=35), then the number mod 97 must equal 1.
What this calculator does
Calculate IBAN Validator step by step: Move the first four characters to the end, convert letters to numbers (A=10 … Z=35), then the number mod 97 must equal 1. Worked example, questions and limitations included.
Use it to turn IBAN into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this developer tools calculation.
Inputs and what they mean
- IBAN
- — text value.
How to use it
- Enter each value in the unit shown next to the box (use the unit converter first if your numbers are in other units).
- Check the breakdown to see every intermediate step.
- Read the limitations before relying on the result.
Formula
The mod-97 check digit algorithm from ISO 13616.
Format and checksum are validated; country-specific length and bank-code structure are not checked.
A passing checksum means the number is well-formed, not that the account exists or is open.
Move the first four characters to the end, convert letters to numbers (A=10 … Z=35), then the number mod 97 must equal 1.
Inputs used: IBAN.
Worked example
A UK IBAN
- Rearrange: NWBK60161331926819GB29.
- Convert letters: N=23, W=32, B=11, K=20, G=16, B=11.
- The resulting number mod 97 = 1, so the checksum passes.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Checksum and format only — no registry lookup.
- Does not confirm the account exists.
- Country-specific structure is not validated.
- Results are computed only from the values you enter. Check the limitations before relying on them.
- The result depends on the values you enter for this iban validator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Common questions
Does a valid result mean the account exists?
No. The checksum only proves the number is well-formed and free of common typing errors.
Why isn't the country length checked?
Country-specific BBAN lengths come from the IBAN registry; this validator checks the universal format and checksum only, and says so rather than guessing. Check the formula, example, and limitations on this page before using the result for a real developer tools decision.
Can I enter it with spaces?
Yes — spaces are ignored. Check the formula, example, and limitations on this page before using the result for a real developer tools decision.
How do I use the IBAN Validator?
Enter the required values for IBAN. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the IBAN Validator use?
Move the first four characters to the end, convert letters to numbers (A=10 … Z=35), then the number mod 97 must equal 1. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.
Can the IBAN Validator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.