Browse 122 check digit tools by name or category. Find a barcode standard, bank or identity format, or checksum test. Open a tool to see its inputs, rules and worked examples.
Core Algorithms & Modulus(17)
Luhn Calculator
Calculate or verify Modulus 10 digits.
Luhn Mod N Calculator
Extend Luhn to custom character sets.
Verhoeff Calculator
Calculate permutation-based check digits.
Damm Calculator
Calculate quasigroup-based check digits.
GS1 Modulus 10 Calculator
Apply alternating positional weights.
Weighted Modulus 10 Calculator
Use configurable digit weights.
Weighted Modulus 11 Calculator
Configure weights and remainder handling.
Modulus 97 Calculator
Calculate numeric remainders and check values.
Custom Modulus Calculator
Specify modulus, weights, and output rules.
ISO 7064 MOD 11-2 Calculator
Calculate numeric check characters.
ISO 7064 MOD 37-2 Calculator
Calculate alphanumeric check characters.
ISO 7064 MOD 97-10 Calculator
Calculate two numeric check digits.
ISO 7064 MOD 661-26 Calculator
Calculate two alphabetic check characters.
ISO 7064 MOD 1271-36 Calculator
Calculate two alphanumeric check characters.
ISO 7064 MOD 11,10 Calculator
Apply the numeric hybrid system.
ISO 7064 MOD 27,26 Calculator
Apply the alphabetic hybrid system.
ISO 7064 MOD 37,36 Calculator
Apply the alphanumeric hybrid system.
GS1 & Retail Barcodes(16)
GTIN Check Digit Calculator
Select the applicable GTIN length. GS1
GTIN-8 / EAN-8 Calculator
Complete eight-digit product identifiers.
GTIN-12 / UPC-A Calculator
Complete twelve-digit product identifiers.
GTIN-13 / EAN-13 Calculator
Complete thirteen-digit product identifiers.
GTIN-14 / ITF-14 Calculator
Complete fourteen-digit trade item identifiers.
UPC-E Check Digit Calculator
Calculate through UPC-A expansion.
GLN Check Digit Calculator
Check Global Location Number digits.
SSCC Check Digit Calculator
Check logistics-unit identifier digits.
GRAI Check Digit Calculator
Check the returnable-asset identification component.
GDTI Check Digit Calculator
Check the document identification component.
GSRN Check Digit Calculator
Check service relationship identifiers.
GSIN Check Digit Calculator
Check shipment identification digits.
GCN Check Digit Calculator
Check coupon identification components.
ITIP Check Digit Calculator
Check individual trade item piece identifiers.
GMN Check Character Calculator
Calculate model-number check character pairs.
Chilean RUT Check Digit Calculator
Calculate numeric or K check characters.
Publishing & Identifiers(9)
ISBN-10 Check Digit Calculator
Calculate numeric or X check characters.
ISBN-13 Check Digit Calculator
Calculate thirteen-digit book identifier checks.
ISBN-10 to ISBN-13 Converter
Convert eligible ISBNs and recalculate checks.
ISBN-13 to ISBN-10 Converter
Convert eligible 978-prefix ISBNs.
ISSN Check Digit Calculator
Check serial publication identifiers.
ISMN Check Digit Calculator
Check music publication identifiers.
ISNI Check Digit Calculator
Check public identity identifier digits.
ORCID Check Digit Calculator
Apply MOD 11-2 checksum validation. ORCID
ISAN Check Character Calculator
Check audiovisual identifier components.
Industrial & Barcode Symbologies(9)
Code 39 Checksum Calculator
Calculate optional Modulus 43 characters.
Code 93 Checksum Calculator
Calculate C and K characters.
Code 128 Checksum Calculator
Calculate the symbol check value.
MSI Mod 10 Calculator
Calculate MSI barcode check digits.
MSI Mod 11 Calculator
Apply the selected weighting variant.
MSI Mod 1010 Calculator
Calculate two successive Mod 10 digits.
MSI Mod 1110 Calculator
Combine Mod 11 and Mod 10.
Codabar Checksum Calculator
Apply a selected optional checksum convention.
Interleaved 2 of 5 Checksum Calculator
Apply a selected check-digit convention.
Diagnostic, Analysis & Utilities(23)
GS1-128 Symbol Checksum Calculator
Check encoded Code 128 symbol values.
Check Digit Generator
Append checks using a selected scheme.
Check Digit Validator
Compare supplied and calculated check characters.
Check Digit Replacement Tool
Recalculate an incorrect check field.
Check Digit Extraction Tool
Isolate scheme-specific check characters.
Identifier Scheme Finder
Suggest compatible formats and checksum schemes.
Check Digit Support Lookup
Identify schemes with check characters.
Algorithm Comparison Tool
Compare outputs for the same input.
Step-by-Step Checksum Calculator
Show weights, products, and remainders.
Transposition Error Simulator
Test swapped-digit detection.
Checksum Collision Explorer
Find different inputs sharing check values.
Custom Weight Sequence Builder
Configure repeating positional weights.
Check Character Mapping Tool
Configure values such as X.
Identifier Format Validator
Check length and permitted characters.
Identifier Normalization Tool
Apply scheme-specific separator handling.
Bulk Check Digit Generator
Complete multiple identifiers together.
Bulk Checksum Validator
Check multiple identifiers together.
CSV Check Digit Processor
Process identifiers from spreadsheet exports.
Sequential Identifier Completion Tool
Append checks to supplied sequences.
Check Digit Test Vector Generator
Create examples for implementation checks.
Spreadsheet Formula Generator
Produce scheme-specific calculation formulas.
Check Digit Code Generator
Produce selected algorithm implementations.
Checksum Validation Report Generator
Export results and failure explanations.
Banking & Financial Standards(18)
IBAN Check Digit Calculator
Calculate international account check digits. SWIFT
IBAN Checksum Validator
Verify existing IBAN check digits.
National Bank Account Checksum Tool
Apply country-specific account rules.
ABA Routing Number Calculator
Calculate US routing check digits.
Spanish CCC Check Digit Calculator
Calculate domestic account control digits.
French RIB Key Calculator
Calculate bank account control keys.
Belgian Account Check Digit Calculator
Check domestic account control digits.
RF Creditor Reference Calculator
Calculate structured payment reference digits.
Finnish Payment Reference Calculator
Calculate domestic reference check digits.
Norwegian KID Calculator
Apply the selected reference checksum method.
Swedish OCR Reference Calculator
Calculate payment reference check digits.
Credit Card Check Digit Calculator
Calculate the final Luhn digit.
Credit Card Checksum Validator
Verify numerical checksum consistency.
ISIN Check Digit Calculator
Check securities identification numbers.
CUSIP Check Digit Calculator
Check securities identifier digits.
SEDOL Check Digit Calculator
Apply weighted security identifier checks. LSEG
FIGI Check Digit Calculator
Check financial instrument identifier digits. OpenFIGI
LEI Check Digit Calculator
Calculate legal entity identifier checks.
Government & Identity Numbers(22)
IMEI Check Digit Calculator
Calculate device identifier Luhn digits.
ICCID Check Digit Calculator
Check SIM identifier checksums.
NPI Check Digit Calculator
Apply healthcare provider identifier rules.
NHS Number Check Digit Calculator
Check NHS identifier control digits.
Canadian SIN Checksum Validator
Verify Social Insurance Number checksums.
Aadhaar Checksum Validator
Verify the Verhoeff check digit.
South African ID Checksum Validator
Verify identifier checksum consistency.
Israeli ID Checksum Validator
Apply weighted identifier checksum rules.
Swedish Personal Number Validator
Verify personal identifier checksums.
Finnish Personal Identity Check Calculator
Calculate the identifier check character.
Spanish NIF Check Letter Calculator
Calculate tax identifier control letters.
Spanish NIE Check Letter Calculator
Calculate foreign-resident identifier control letters.
Portuguese NIF Check Digit Calculator
Check tax identifier control digits.
Brazilian CPF Check Digit Calculator
Calculate individual taxpayer check digits.
Brazilian CNPJ Checksum Validator
Apply format-specific business identifier rules.
Australian ABN Checksum Validator
Verify business number checksum consistency.
Australian ACN Check Digit Calculator
Calculate company number check digits.
Australian TFN Checksum Validator
Verify tax file number checksums.
Identity Card MRZ Calculator
Check document fields and composite digits.
Missing Digit Solver
Find checksum-compatible missing digits.
Missing Character Solver
Find compatible alphanumeric characters.
Single-Digit Error Simulator
Test detection of digit substitutions.
Transport, Shipping & Travel(8)
VIN Check Digit Calculator
Apply the applicable vehicle checksum rules.
ISO 6346 Container Calculator
Calculate freight-container check digits. BIC
UPU S10 Check Digit Calculator
Check international postal item identifiers. UPU
IMO Ship Number Calculator
Check seven-digit ship identifier checksums.
Railway Vehicle Check Digit Calculator
Check European vehicle number digits.
ILU-Code Check Digit Calculator
Check intermodal loading unit identifiers.
Passport MRZ Check Digit Calculator
Check machine-readable passport fields.
Custom Serial Number Calculator
Apply configured serial checksum rules.