🇫🇮Finnish Business ID (Y-tunnus) Validator

Y-tunnus validator -- check a Finnish business ID online

Our free Y-tunnus validator instantly checks the validity of a Finnish business identity code using the MOD-11 algorithm. Simply type or paste the number in the format 1234567-8 or without the hyphen -- spaces are ignored automatically. The tool verifies the check digit and immediately shows whether the number is mathematically correct.

If you work with Finnish companies or need to verify registration data before signing a contract, this Y-tunnus validator will help you quickly catch typos and errors. Keep in mind, however, that a valid check digit does not guarantee the company is currently active -- it only confirms the mathematical consistency of the number.

Full privacy -- local processing

Verification takes place entirely in your browser -- not a single digit of the entered number is sent to any server. You can use the validator even offline, and your data stays on your device alone.

Frequently asked questions

What is Y-tunnus and who has one?

Y-tunnus (Finnish business identity code) is a unique identifier assigned by the Finnish Patent and Registration Office (PRH) to every company, association, and foundation registered in Finland. The format is 7 digits, a hyphen, and a check digit, e.g. 1234567-8. It is the Finnish equivalent of a VAT number or company registration number.

How does the MOD-11 algorithm work for Y-tunnus?

Each of the 7 digits is multiplied by a corresponding weight (7, 9, 10, 5, 8, 4, 2) and the products are summed. The sum is divided by 11. If the remainder is 0, the check digit is 0. If the remainder is 1, no valid Y-tunnus exists with those digits. Otherwise, the check digit equals 11 minus the remainder.

Can a Y-tunnus start with a zero?

Yes. A Y-tunnus always has exactly 7 digits before the hyphen, so it can start with one or more zeros, e.g. 0000001-9. All zeros are significant and must be entered.

Does the Y-tunnus validator check whether the company exists?

No. The validator only checks the mathematical correctness of the check digit and the format. To verify whether a company is currently registered, you need to consult the PRH register at ytj.fi or the Business Information System.

Is my data sent to a server?

No. All Y-tunnus validation is performed locally in your browser -- not a single digit entered reaches any server. You can validate a number even without an internet connection.