WeVividWeVividGenerate a scannable EAN-13 barcode from a 10 or 13-digit ISBN, ready for a book cover.
It's prefixed with 978 and a new EAN-13 check digit is calculated, which is the standard way book barcodes are built from older ISBN-10 numbers.
Book barcodes are a specific use of the EAN-13 standard, so the number shown under the barcode is your ISBN in 13-digit form.