# Mod-11 Checksum Calculator Validate or generate numbers using the Modulus-11 (ISO 7064) check-digit algorithm with ISBN-10 (10..2), Norwegian-ID (3,7,6,1,8,9,4,5,2) and generic 2-7 weight schemes. > Canonical page: https://elysiatools.com/en/tools/mod11-checksum - **Category:** Validation - **Keywords:** mod11, modulus 11, iso 7064, check digit, isbn, issn, norwegian id, isbt 128, validator, generator ## Overview The Mod-11 Checksum Calculator allows you to validate or generate numbers using the Modulus-11 (ISO 7064) check-digit algorithm. It supports standard weighting schemes including ISBN-10, Norwegian ID, and generic 2-7 weights to ensure data integrity and prevent input errors. ## Inputs - **Mode** (select) - **Weighting Scheme** (select) - **Number to Validate** (text): Any Mod-11 number. Separators are ignored; the last digit is the check digit. - **Total Length** (number): Total digit count including the check digit (generate mode). - **Prefix (optional)** (text): Lock the leading digits of the generated number. ## When to use - When verifying the validity of ISBN-10 book identifiers or Norwegian national identification numbers. - When generating valid test data or mock identifiers that conform to the Modulus-11 check-digit standard. - When troubleshooting data entry errors in systems that use the ISO 7064 Mod-11 checksum algorithm. ## How it works - Select the operation mode: either validate an existing number or generate a new one. - Choose the appropriate weighting scheme, such as ISBN-10, Norwegian ID, or the generic 2-7 weights. - Input the target number for validation, or specify the desired total length and optional prefix for generation. - The tool calculates the Modulus-11 checksum and outputs the validation result or the newly generated number with its check digit. ## Use cases - Validating ISBN-10 codes during cataloging to ensure no digits were mistyped. - Generating mock Norwegian ID numbers for software testing environments. - Checking custom serial numbers that utilize the generic 2-7 Mod-11 weighting scheme. ## Frequently asked questions ### What weighting schemes does this calculator support? It supports ISBN-10 (weights 10 to 2), Norwegian ID (weights 3,7,6,1,8,9,4,5,2), and a generic scheme (weights 2 to 7). ### How does the validation mode handle spaces or dashes? The tool automatically ignores non-digit separators like spaces and dashes when validating the input number. ### What is the purpose of the prefix option in generate mode? The prefix option locks the leading digits of the generated number, allowing you to create valid numbers with specific starting sequences. ### Can I generate a number of any length? You can generate numbers with a total length ranging from 2 to 30 digits, including the check digit. ### What is the Modulus-11 algorithm? It is a checksum method defined by ISO 7064 that uses weights and a modulo 11 operation to calculate a single check digit, helping detect transcription errors. ## Related tools - [Email Validator](https://elysiatools.com/en/tools/email-validator): Validate email addresses and check deliverability - [Global Phone Validator](https://elysiatools.com/en/tools/global-phone-validator): Validate phone numbers from multiple countries including China, US, and more with detailed formatting and carrier info - [IBAN & SWIFT Validator](https://elysiatools.com/en/tools/iban-swift-validator): Validate International Bank Account Number (IBAN) and SWIFT/BIC codes with checksum verification - [IMEI Validator](https://elysiatools.com/en/tools/imei-validator): Validate IMEI numbers for mobile devices using Luhn checksum algorithm - [IMSI Validator](https://elysiatools.com/en/tools/imsi-validator): Validate IMSI numbers for mobile subscribers with MCC/MNC analysis - [IP Address Validator](https://elysiatools.com/en/tools/ip-address-validator): Validate IPv4 and IPv6 addresses with CIDR notation support - [Phone Validator](https://elysiatools.com/en/tools/phone-validator): Validate and format phone numbers internationally - [ABA Routing Number Validator](https://elysiatools.com/en/tools/routing-number-validator): Validate 9-digit US ABA bank routing numbers (RTN) with MICR check-digit verification, Federal Reserve district lookup and ABA institution breakdown. ## Samples - [Android Image Processing Java Samples](https://elysiatools.com/en/samples/android-image-processing-java): Android Java image processing examples including reading/saving images, scaling, and format conversion - [Android Image Processing Kotlin Samples](https://elysiatools.com/en/samples/android-image-processing-kotlin): Android Kotlin image processing examples including reading/saving images, scaling, and format conversion - [Web Image Processing Python Samples](https://elysiatools.com/en/samples/web-image-processing-python): Web Python image processing examples using PIL/Pillow including reading, saving, resizing, and format conversion - [Web Image Processing Rust Samples](https://elysiatools.com/en/samples/web-image-processing-rust): Web Rust image processing examples including image read/save, scaling, and format conversion ## Related content - [Check Digit, Checksum, and Identifier Validation Tools](https://elysiatools.com/en/hubs/check-digit-checksum-validation): Validate Luhn, Mod-11, GTIN, ISBN, IMEI, ICCID, VIN, IBAN, and ISIN codes in one focused hub for checksum-driven identifier checks. - [Identifier, Config, and Input Validation Tools](https://elysiatools.com/en/hubs/validation-validate): Compare validators for email, phone, IP, dates, cron, barcodes, payment details, env files, and other real-world inputs in one hub. - [Identifier, Address, and Code Format Validators](https://elysiatools.com/en/hubs/validation-format): Curated tools for identifier, address, account, and code format validation in one hub. - [Contact, Postal, and Shipping Validation Tools](https://elysiatools.com/en/hubs/contact-shipping-validation): Validate emails, phone numbers, postal codes, calling codes, and shipment tracking numbers in one hub for signup, checkout, and delivery workflows.