All tools › Identifiers and check digits
ISBN 10 and 13 converter
Both forms of a book, journal and sheet-music numbers too — and it refuses the conversion that has no answer.
It runs entirely in this browser tab: what you type is never uploaded, and the tool makes no network request while it works. Open your browser's network panel and try it — nothing leaves the page. There is no sign-up and no limit beyond what your own browser can hold.
Settings
- Write as
- A number beginning 979 has no ten-digit form at all, and the tool refuses rather than inventing one. Choices: Both, Ten digits, Thirteen digits.
- Put the hyphens in
- Prefix, registration group, the rest, check digit. The publisher's own hyphen needs a table larger than this application.
How to use it
- Paste your text into the box above, or open a file.
- Adjust the settings beside it until the result is what you wanted.
- Copy the result, or save it as a file. The result updates as you type.
Questions
- Is what I type uploaded anywhere?
- No. This page carries the whole tool as WebAssembly and runs it on your own device. Nothing you type is sent anywhere, and there is no network request to make while it works.
- How exact is the arithmetic?
- Exact, in decimal, for everything the tool was given: no value here is put through floating point on the way to the answer. Where there is a genuine ceiling — thirty-nine digits for the number-theory tools, a fixed number of places for a repeating fraction — the tool says the limit rather than quietly truncating.
- Can I get this result again later?
- The settings travel in the page's address, after the #, so a link reproduces them exactly — and the fragment of an address is never sent to a server. Your last settings are also remembered on this device, which is worth knowing before you paste a number you would not want left there.
- Is there a version that is not a web page?
- Yes. The same tools are built as a desktop application from the same code, with a save dialog instead of a download and no network code at all.
Other tools for identifiers and check digits
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Luhn, GTIN, ISBN, modulo eleven and the two ISO 7064 rules, with the working digit by digit.
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The check that catches a mistyped account before the payment leaves — fifty-one countries, and the Slovak and Czech national forms.
VAT number format validator
Every European Union country's format, and the national check digit wherever this tool actually has the algorithm.
National ID number validator
The Slovak and Czech rules, historical exceptions included, on your own device and nowhere else.
Credit card number validator
The checksum and the issuer, and test numbers for a payment form — none of it leaving this device.
All thirty-one tools