ISBN lookup
Validate an ISBN-10 or ISBN-13, convert between them, and decode its registration group — instantly, in your browser. Optionally fetch the book's title and author.
Validation, conversion and the group decode run entirely in your browser. Fetching book details makes one call to Open Library.
ISBN registration groups
The digits right after the 978/979 prefix are the registration group — the country or
language area. The one- and two-digit groups below cover most books in print; smaller national groups use three
or more digits.
Language groups (978, one digit)
978-0 | English language |
978-1 | English language |
978-2 | French language |
978-3 | German language |
978-4 | Japan |
978-5 | Russia / former USSR |
978-7 | China |
National groups (978, two digits)
978-80 | Czech Republic / Slovakia |
978-81 | India |
978-82 | Norway |
978-83 | Poland |
978-84 | Spain |
978-85 | Brazil |
978-86 | Serbia / Montenegro |
978-87 | Denmark |
978-88 | Italy |
978-89 | Korea, Republic of |
978-90 | Netherlands |
978-91 | Sweden |
978-92 | International (UN, UNESCO, EU) |
978-93 | India |
978-94 | Netherlands |
978-65 | Brazil |
National groups (978, three digits)
978-600 | Iran |
978-601 | Kazakhstan |
978-602 | Indonesia |
978-603 | Saudi Arabia |
978-604 | Vietnam |
978-605 | Türkiye |
978-606 | Romania |
978-607 | Mexico |
978-608 | North Macedonia |
978-609 | Lithuania |
978-611 | Thailand |
978-612 | Peru |
978-613 | Mauritius |
978-614 | Lebanon |
978-615 | Hungary |
978-616 | Thailand |
978-617 | Ukraine |
978-618 | Greece |
978-619 | Bulgaria |
978-620 | Mauritius |
978-621 | Philippines |
978-622 | Iran |
978-623 | Indonesia |
978-624 | Sri Lanka |
978-625 | Türkiye |
978-626 | Taiwan |
978-627 | Pakistan |
978-628 | Colombia |
978-629 | Malaysia |
978-630 | Romania |
978-631 | Argentina |
978-950 | Argentina |
978-951 | Finland |
978-952 | Finland |
978-953 | Croatia |
978-954 | Bulgaria |
978-955 | Sri Lanka |
978-956 | Chile |
978-957 | Taiwan |
978-958 | Colombia |
978-959 | Cuba |
978-960 | Greece |
978-961 | Slovenia |
978-962 | Hong Kong |
978-963 | Hungary |
978-964 | Iran |
978-965 | Israel |
978-966 | Ukraine |
978-967 | Malaysia |
978-968 | Mexico |
978-969 | Pakistan |
978-970 | Mexico |
978-971 | Philippines |
978-972 | Portugal |
978-973 | Romania |
978-974 | Thailand |
978-975 | Türkiye |
978-976 | Caribbean Community |
978-977 | Egypt |
978-978 | Nigeria |
978-979 | Indonesia |
978-980 | Venezuela |
978-981 | Singapore |
978-982 | South Pacific |
978-983 | Malaysia |
978-984 | Bangladesh |
978-985 | Belarus |
978-986 | Taiwan |
978-987 | Argentina |
978-988 | Hong Kong |
978-989 | Portugal |
Prefix 979
979-8 | United States |
979-10 | France |
979-11 | Korea, Republic of |
979-12 | Italy |
How to look up an ISBN
- Enter an ISBN. Paste a 10- or 13-digit ISBN, with or without hyphens.
- Validate & decode. The check digit, ISBN-10/13 forms and registration group are computed in your browser.
- Optionally fetch details. Press "Look up book details" to pull the title and author from Open Library.
How an ISBN is built
An ISBN-13 is five parts read left to right. It opens with a prefix — 978, or
979 once the 978 space filled up — which also makes the number a valid EAN-13 barcode. Then comes the
registration group, the country or language area (one to five digits: 0 and
1 are the English group, 3 German, 89 the Republic of Korea,
607 Mexico). Next is the registrant — the specific publisher — and the
publication element, which identifies the title and edition. The final digit is the
check digit. The group and registrant blocks have variable length, which is why the internal
hyphenation shifts from one ISBN to the next; only the prefix, group and check digit sit at fixed, knowable
boundaries, so those are the parts this tool splits with confidence.
The check digit, and why it matters
The last character exists to catch copying mistakes. ISBN-10 uses a weighted mod-11 sum, so its
check can legitimately be the letter X (the value ten). ISBN-13 uses the EAN-13
mod-10 scheme, alternating weights of 1 and 3, so its check is always a digit. Both schemes reliably flag any
single wrong digit and most swaps of two adjacent digits — the errors that actually happen when someone keys an
ISBN from a copyright page. That is also why converting ISBN-10 to ISBN-13 changes the last digit:
you keep the nine core digits, prepend 978, and recompute the checksum under the new rules. Only
978-prefixed 13s convert back to a 10-digit number — 979 ISBNs never had a 10-digit form.
What a valid ISBN does and doesn't prove
A passing check digit proves only that the number is well-formed. It does not prove a book with that ISBN exists, is in print, or matches the title on the shelf — a number can be valid yet unassigned, and a real book may not be catalogued in any public database. This tool does the validation, conversion and group decode locally in your browser; the optional "Look up book details" button is the one action that sends the ISBN anywhere, fetching the public catalogue record from Open Library. To validate a different kind of check-digit identifier, the IBAN validator and VIN decoder work the same way.
Frequently asked questions
- It validates the check digit of a 10- or 13-digit ISBN, converts between ISBN-10 and ISBN-13, and decodes the registration group — the country or language area the book was registered in. Optionally it fetches the title, author and cover from Open Library.
- ISBN-10 was the standard until 2007; ISBN-13 replaced it by prefixing the number with 978 (or 979) and recalculating the final check digit. A 978-prefixed ISBN-13 converts cleanly back to a 10-digit ISBN; a 979-prefixed one has no 10-digit form.
- The last character is a checksum computed from the others — mod 11 for ISBN-10 (where a remainder of 10 is written as X) and the EAN-13 mod-10 scheme for ISBN-13. It catches the single-digit typos and adjacent-digit swaps people make when copying a number.
- The digits after the 978/979 prefix are the registration group, which identifies the country or language area — for example 0 and 1 are the English-language group, 3 is German, 89 is the Republic of Korea, 607 is Mexico. It does not identify the individual publisher on its own.
- The validation, conversion and group decode run entirely in your browser. Only if you press "Look up book details" does the ISBN leave your device — that one call goes to Open Library through our server to fetch the public catalogue record.
- No. A valid check digit only proves the number is correctly formed. A book may have a valid ISBN that Open Library has never catalogued, and a number can be well-formed but never assigned to any title.