ISBN Barcode Reader
Validate ISBN-10 and ISBN-13 book barcodes, convert between formats, and learn how the Bookland prefix works. Runs locally in your browser.
Result
Paste an ISBN and press Validate. The detected format, cleaned number, and the matching ISBN-10/ISBN-13 conversion will appear here.
How a book barcode is built
An ISBN-13 packs five segments into 13 digits. The hyphens you see in print are purely visual — the underlying barcode never stores them.
Bookland GS1 prefix that flags the code as a book.
Country, geographic, or language area (e.g. 0 / 1 = English-speaking).
Assigned to a specific publisher by their national ISBN agency.
Identifies the specific edition and format of the title.
mod-11 for ISBN-10 ('X' = 10); mod-10 for ISBN-13.
About this ISBN barcode reader
This ISBN barcode reader validates both the legacy ISBN-10 format and the modern 13-digit ISBN used on every book printed today. It checks the check digit with the correct algorithm for each format — mod-11 with an 'X' fallback for ISBN-10, and the GS1 mod-10 for ISBN-13 — and converts between the two whenever the prefix allows it.
Everything runs in your browser. No upload, no signup, no third-party lookup of confidential pre-publication catalog data.
When to use it
- Validating an ISBN scraped from a publisher's catalog before importing it into your library system.
- Cleaning up a list of book identifiers that mixes ISBN-10s and ISBN-13s.
- Confirming that a self-published title's freshly assigned ISBN-13 has the right check digit before sending to a printer.
- Converting between ISBN-10 and ISBN-13 when migrating legacy bibliographic data.
- Debugging why a book listing is being rejected by Amazon, Ingram, or a library catalog feed.
How it works
- Paste the ISBN
Type or paste a 10- or 13-character ISBN. Hyphens, spaces, dots and underscores are stripped automatically.
- Auto-detect the format
Length determines whether it's treated as ISBN-10 (10 chars, last may be X) or ISBN-13 (13 digits, must start 978/979).
- Run the right check
ISBN-10 uses a mod-11 weighted sum; ISBN-13 uses the standard EAN-13 mod-10. Mismatches show the expected check digit.
- Convert when possible
Valid ISBN-10s are converted to ISBN-13 (978 prefix). Valid 978-ISBN-13s are converted back to ISBN-10. 979-codes have no ISBN-10 form.
- Copy the cleaned number
Copy the normalized hyphen-free ISBN — the form retailers and feeds expect.
What to avoid
- Treating a lowercase 'x' in an ISBN-10 as invalid — it's the same as 'X' and represents the value 10.
- Assuming every ISBN-13 can be downgraded to ISBN-10. Only the 978-prefix range converts.
- Using an ISSN (serial publications) where an ISBN is expected — they look similar but use different ranges and algorithms.
- Importing ISBNs straight from a spreadsheet without trimming hidden apostrophes or non-breaking spaces.
- Hand-fixing the check digit by guessing instead of recomputing it — typos in the body almost always look like one-off check digit errors.
Tips & tricks
- If validation fails by one digit, the typo is almost always in the body of the ISBN, not the check digit.
- Every ISBN-13 is also a valid EAN-13 — paste it into the EAN Lookup tool to inspect the GS1 country prefix.
- Bookstores often print the ISBN-13 above the bars and the older ISBN-10 below. Both should resolve to the same book.
- Need to recompute a missing ISBN-13 check digit from the first 12 characters? Use the Check Digit Calculator.
- When in doubt about a barcode's format, the Barcode Type Detector will identify ISBN-10 / ISBN-13 alongside UPC/EAN/GTIN.