Explore all tools, algorithm engines, symbology calculators, and legal resources across CheckDigitLab from this unified directory.
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Check Digit Calculator & Live Validator (Home)Interactive computation instrument, barcode preview, and step-by-step arithmetic visualizer.Check Digit Subtools DirectoryDirectory of all 122 check digit calculators and validation instruments.About UsWho runs CheckDigitLab, our engineering principles and standards.Contact UsSupport inquiries, technical questions, and algorithm feedback channels.Privacy PolicyOur commitment to client-side zero-knowledge computation.Terms & ConditionsService guidelines, disclaimers, and terms governing website use.
All 122 Check Digit Subtools & Calculators
View Interactive Directory →Category: Core Algorithms & Modulus (17)
Luhn CalculatorCalculate or verify Modulus 10 digits.
Luhn Mod N CalculatorExtend Luhn to custom character sets.
Verhoeff CalculatorCalculate permutation-based check digits.
Damm CalculatorCalculate quasigroup-based check digits.
GS1 Modulus 10 CalculatorApply alternating positional weights.
Weighted Modulus 10 CalculatorUse configurable digit weights.
Weighted Modulus 11 CalculatorConfigure weights and remainder handling.
Modulus 97 CalculatorCalculate numeric remainders and check values.
Custom Modulus CalculatorSpecify modulus, weights, and output rules.
ISO 7064 MOD 11-2 CalculatorCalculate numeric check characters.
ISO 7064 MOD 37-2 CalculatorCalculate alphanumeric check characters.
ISO 7064 MOD 97-10 CalculatorCalculate two numeric check digits.
ISO 7064 MOD 661-26 CalculatorCalculate two alphabetic check characters.
ISO 7064 MOD 1271-36 CalculatorCalculate two alphanumeric check characters.
ISO 7064 MOD 11,10 CalculatorApply the numeric hybrid system.
ISO 7064 MOD 27,26 CalculatorApply the alphabetic hybrid system.
ISO 7064 MOD 37,36 CalculatorApply the alphanumeric hybrid system.
Category: GS1 & Retail Barcodes (16)
GTIN Check Digit CalculatorSelect the applicable GTIN length. GS1
GTIN-8 / EAN-8 CalculatorComplete eight-digit product identifiers.
GTIN-12 / UPC-A CalculatorComplete twelve-digit product identifiers.
GTIN-13 / EAN-13 CalculatorComplete thirteen-digit product identifiers.
GTIN-14 / ITF-14 CalculatorComplete fourteen-digit trade item identifiers.
UPC-E Check Digit CalculatorCalculate through UPC-A expansion.
GLN Check Digit CalculatorCheck Global Location Number digits.
SSCC Check Digit CalculatorCheck logistics-unit identifier digits.
GRAI Check Digit CalculatorCheck the returnable-asset identification component.
GDTI Check Digit CalculatorCheck the document identification component.
GSRN Check Digit CalculatorCheck service relationship identifiers.
GSIN Check Digit CalculatorCheck shipment identification digits.
GCN Check Digit CalculatorCheck coupon identification components.
ITIP Check Digit CalculatorCheck individual trade item piece identifiers.
GMN Check Character CalculatorCalculate model-number check character pairs.
Chilean RUT Check Digit CalculatorCalculate numeric or K check characters.
Category: Publishing & Identifiers (9)
ISBN-10 Check Digit CalculatorCalculate numeric or X check characters.
ISBN-13 Check Digit CalculatorCalculate thirteen-digit book identifier checks.
ISBN-10 to ISBN-13 ConverterConvert eligible ISBNs and recalculate checks.
ISBN-13 to ISBN-10 ConverterConvert eligible 978-prefix ISBNs.
ISSN Check Digit CalculatorCheck serial publication identifiers.
ISMN Check Digit CalculatorCheck music publication identifiers.
ISNI Check Digit CalculatorCheck public identity identifier digits.
ORCID Check Digit CalculatorApply MOD 11-2 checksum validation. ORCID
ISAN Check Character CalculatorCheck audiovisual identifier components.
Category: Industrial & Barcode Symbologies (9)
Code 39 Checksum CalculatorCalculate optional Modulus 43 characters.
Code 93 Checksum CalculatorCalculate C and K characters.
Code 128 Checksum CalculatorCalculate the symbol check value.
MSI Mod 10 CalculatorCalculate MSI barcode check digits.
MSI Mod 11 CalculatorApply the selected weighting variant.
MSI Mod 1010 CalculatorCalculate two successive Mod 10 digits.
MSI Mod 1110 CalculatorCombine Mod 11 and Mod 10.
Codabar Checksum CalculatorApply a selected optional checksum convention.
Interleaved 2 of 5 Checksum CalculatorApply a selected check-digit convention.
Category: Diagnostic, Analysis & Utilities (23)
GS1-128 Symbol Checksum CalculatorCheck encoded Code 128 symbol values.
Check Digit GeneratorAppend checks using a selected scheme.
Check Digit ValidatorCompare supplied and calculated check characters.
Check Digit Replacement ToolRecalculate an incorrect check field.
Check Digit Extraction ToolIsolate scheme-specific check characters.
Identifier Scheme FinderSuggest compatible formats and checksum schemes.
Check Digit Support LookupIdentify schemes with check characters.
Algorithm Comparison ToolCompare outputs for the same input.
Step-by-Step Checksum CalculatorShow weights, products, and remainders.
Transposition Error SimulatorTest swapped-digit detection.
Checksum Collision ExplorerFind different inputs sharing check values.
Custom Weight Sequence BuilderConfigure repeating positional weights.
Check Character Mapping ToolConfigure values such as X.
Identifier Format ValidatorCheck length and permitted characters.
Identifier Normalization ToolApply scheme-specific separator handling.
Bulk Check Digit GeneratorComplete multiple identifiers together.
Bulk Checksum ValidatorCheck multiple identifiers together.
CSV Check Digit ProcessorProcess identifiers from spreadsheet exports.
Sequential Identifier Completion ToolAppend checks to supplied sequences.
Check Digit Test Vector GeneratorCreate examples for implementation checks.
Spreadsheet Formula GeneratorProduce scheme-specific calculation formulas.
Check Digit Code GeneratorProduce selected algorithm implementations.
Checksum Validation Report GeneratorExport results and failure explanations.
Category: Banking & Financial Standards (18)
IBAN Check Digit CalculatorCalculate international account check digits. SWIFT
IBAN Checksum ValidatorVerify existing IBAN check digits.
National Bank Account Checksum ToolApply country-specific account rules.
ABA Routing Number CalculatorCalculate US routing check digits.
Spanish CCC Check Digit CalculatorCalculate domestic account control digits.
French RIB Key CalculatorCalculate bank account control keys.
Belgian Account Check Digit CalculatorCheck domestic account control digits.
RF Creditor Reference CalculatorCalculate structured payment reference digits.
Finnish Payment Reference CalculatorCalculate domestic reference check digits.
Norwegian KID CalculatorApply the selected reference checksum method.
Swedish OCR Reference CalculatorCalculate payment reference check digits.
Credit Card Check Digit CalculatorCalculate the final Luhn digit.
Credit Card Checksum ValidatorVerify numerical checksum consistency.
ISIN Check Digit CalculatorCheck securities identification numbers.
CUSIP Check Digit CalculatorCheck securities identifier digits.
SEDOL Check Digit CalculatorApply weighted security identifier checks. LSEG
FIGI Check Digit CalculatorCheck financial instrument identifier digits. OpenFIGI
LEI Check Digit CalculatorCalculate legal entity identifier checks.
Category: Government & Identity Numbers (22)
IMEI Check Digit CalculatorCalculate device identifier Luhn digits.
ICCID Check Digit CalculatorCheck SIM identifier checksums.
NPI Check Digit CalculatorApply healthcare provider identifier rules.
NHS Number Check Digit CalculatorCheck NHS identifier control digits.
Canadian SIN Checksum ValidatorVerify Social Insurance Number checksums.
Aadhaar Checksum ValidatorVerify the Verhoeff check digit.
South African ID Checksum ValidatorVerify identifier checksum consistency.
Israeli ID Checksum ValidatorApply weighted identifier checksum rules.
Swedish Personal Number ValidatorVerify personal identifier checksums.
Finnish Personal Identity Check CalculatorCalculate the identifier check character.
Spanish NIF Check Letter CalculatorCalculate tax identifier control letters.
Spanish NIE Check Letter CalculatorCalculate foreign-resident identifier control letters.
Portuguese NIF Check Digit CalculatorCheck tax identifier control digits.
Brazilian CPF Check Digit CalculatorCalculate individual taxpayer check digits.
Brazilian CNPJ Checksum ValidatorApply format-specific business identifier rules.
Australian ABN Checksum ValidatorVerify business number checksum consistency.
Australian ACN Check Digit CalculatorCalculate company number check digits.
Australian TFN Checksum ValidatorVerify tax file number checksums.
Identity Card MRZ CalculatorCheck document fields and composite digits.
Missing Digit SolverFind checksum-compatible missing digits.
Missing Character SolverFind compatible alphanumeric characters.
Single-Digit Error SimulatorTest detection of digit substitutions.
Category: Transport, Shipping & Travel (8)
VIN Check Digit CalculatorApply the applicable vehicle checksum rules.
ISO 6346 Container CalculatorCalculate freight-container check digits. BIC
UPU S10 Check Digit CalculatorCheck international postal item identifiers. UPU
IMO Ship Number CalculatorCheck seven-digit ship identifier checksums.
Railway Vehicle Check Digit CalculatorCheck European vehicle number digits.
ILU-Code Check Digit CalculatorCheck intermodal loading unit identifiers.
Passport MRZ Check Digit CalculatorCheck machine-readable passport fields.
Custom Serial Number CalculatorApply configured serial checksum rules.
Calculator in Other Languages
Supported Check Digit Algorithms & Symbologies
Category: Retail & Barcode
MOD 1012 digits
EAN-13 / GTIN-13International retail barcode format used globally on supermarket and consumer goods.MOD 1011 digits
UPC-A / GTIN-12Standard 12-digit barcode used primarily in North America for point-of-sale retail.MOD 107 digits
EAN-8 / GTIN-8Compact barcode designed for small packages where standard EAN-13 barcodes will not fit.MOD 1012 digits
ISBN-13 (Books)International Standard Book Number used on books, textbooks, and published works worldwide.Category: Logistics
MOD 1013 digits
GTIN-14 / ITF-14Global Trade Item Number used on wholesale outer cartons and shipping cases.MOD 1017 digits
SSCC-18Serial Shipping Container Code identifying individual logistics handling units and pallets.MOD 1021 digits
USPS Delivery Confirmation (Mod 10)United States Postal Service 20 or 22-digit tracking barcode standard.Category: Identity & Cards
Category: Financial & Securities
MOD 97Variable
MOD 97-10 (IBAN / ISO 7064)International Bank Account Number check digits (places 3 and 4) using ISO 7064 Modulo 97.MOD 108 digits
CUSIP (North American Securities)9-character alphanumeric identifier for North American financial securities.MOD 106 digits
SEDOL (UK Securities)Stock Exchange Daily Official List identifier for securities in the United Kingdom and Ireland.MOD 1011 digits
ISIN (International Securities)12-character International Securities Identification Number linking global stocks and bonds.Machine-Readable Feeds
For automated indexing robots and search systems:
- robots.txt — Crawling instructions and sitemap directives
- sitemap-index.xml — XML sitemap with hreflang alternates for search engines
- llms.txt — Plaintext LLM documentation for assistant parsers