Canadian · Validation

ISWC check digit validator & calculator.

Check the format and check digit of an International Standard Musical Work Code such as T-034.524.680-1, or enter the 9-digit work number to have the check digit computed. Format and checksum only. Everything runs in your browser: nothing you type is transmitted anywhere.

ISO 15707, administered by CISAC — identifies a musical work, not a recording Cannot confirm the ISWC was ever issued or which work it names

Inputs

Result

Enter an ISWC and press Validate.

How the ISWC check digit works

An ISWC (International Standard Musical Work Code, ISO 15707) is the letter T, a 9-digit work number and 1 check digit, usually written T-123.456.789-C. The prefix T means “musical work” and is the only prefix defined. The dots and dashes are for readability only. Number the nine work digits d₁ to d₉ from the left and add 1 to the sum of each digit times its position: S = 1 + Σ i·d_i. The check digit is C = (10 − (S mod 10)) mod 10.

Worked example, T-034.524.680-C: digits 0, 3, 4, 5, 2, 4, 6, 8, 0 give products 0, 6, 12, 20, 10, 24, 42, 64, 0, so S = 1 + 178 = 179 and C = (10 − 9) mod 10 = 1. The first ISWC ever issued, T-000.000.001-0, follows the same rule.

Sources: Wikipedia’s ISWC article (citing ISO 15707), the django-music-publisher validator check_iswc_digit, and the BTL iswc.py module. All three give the same algorithm.

What a passing checksum does and doesn’t tell you

This tool checks format and checksum only. A valid check digit proves the characters are internally consistent — it cannot confirm the ISWC was ever issued, or which work it identifies. ISWCs are assigned through CISAC’s collecting-society network; look up a real one in the ISWC Net search portal. This tool runs entirely in your browser: nothing you type is transmitted, stored, or logged.