ISBN Validator ISBN Validator Validate ISBN-10 and ISBN-13, strip hyphens and spaces, see checksum steps, and convert ISBN-10 → ISBN-13. 1. Enter ISBN You can paste: 978-0-306-40615-7 or 0-306-40615-2 or even 0306406152 . Validate ISBN 2. Validation Result Type detected — Is valid? — Normalized ISBN — 3. Conversion ISBN-10 → ISBN-13 only when valid. ISBN-13 → ISBN-10 only when it starts with 978. ISBN-10 ➜ ISBN-13 — ISBN-13 ➜ ISBN-10 — 4. Checksum Steps Validate an ISBN to see step-by-step checksum here. How ISBN validation works ISBN-10 For ISBN-10, after stripping hyphens, you must have 10 characters. The checksum is: sum(i × d i ) for i = 1..10 must be divisible by 11 The last digit can be X which means 10. ISBN-13 For ISBN-13, after stripping hyphens, you must have 13 digits. Multiply digits alternately by 1 and 3, sum them, and the total must be divisible by 10. checksum = (d1×1 + d2×3 + d3×1 + d4×3 + ... + d12×3 + d13×1) mod 10 = 0 This tool implements exactly these algorithms so you can trust the result. Related tools Checksum Calculator Number to Words Converter Words to Numbers Converter Core Math & Algebra Why validate ISBNs? To catch typos in book databases, library records, ecommerce listings, or form inputs before saving them.

Calculators in ISBN Validator ISBN Validator Validate ISBN-10 and ISBN-13, strip hyphens and spaces, see checksum steps, and convert ISBN-10 → ISBN-13. 1. Enter ISBN You can paste: 978-0-306-40615-7 or 0-306-40615-2 or even 0306406152 . Validate ISBN 2. Validation Result Type detected — Is valid? — Normalized ISBN — 3. Conversion ISBN-10 → ISBN-13 only when valid. ISBN-13 → ISBN-10 only when it starts with 978. ISBN-10 ➜ ISBN-13 — ISBN-13 ➜ ISBN-10 — 4. Checksum Steps Validate an ISBN to see step-by-step checksum here. How ISBN validation works ISBN-10 For ISBN-10, after stripping hyphens, you must have 10 characters. The checksum is: sum(i × d i ) for i = 1..10 must be divisible by 11 The last digit can be X which means 10. ISBN-13 For ISBN-13, after stripping hyphens, you must have 13 digits. Multiply digits alternately by 1 and 3, sum them, and the total must be divisible by 10. checksum = (d1×1 + d2×3 + d3×1 + d4×3 + ... + d12×3 + d13×1) mod 10 = 0 This tool implements exactly these algorithms so you can trust the result. Related tools Checksum Calculator Number to Words Converter Words to Numbers Converter Core Math & Algebra Why validate ISBNs? To catch typos in book databases, library records, ecommerce listings, or form inputs before saving them..