ABA Routing Checksum Validator
Validate exact nine-digit ABA 3/7/1 checksum, preserving leading zeros and exposing all-zero input separately; not directory assignment, routing-prefix eligibility, bank identity or Fedwire participation verification.
Description
The ABA routing checksum detects some transcription errors using weighted digits.
The ABA routing checksum detects some transcription errors using weighted digits. Checksum agreement alone cannot establish a real routing assignment.1
The returned values include Weighted routing checksum matches, Checksum remainder, Nonzero routing digits observed. The How section below explains the calculation, input rules and interpretation.
When to use ABA Routing Checksum Validator
Use ABA Routing Checksum Validator when you need to evaluate the supplied records under the calculation and evidence rules below. No directory assignment, prefix eligibility, bank identity or Fedwire participation is verified.
Gather verified caller country/notation requirements. Keep identifiers as strings so leading zeros survive; supply the applicable lookup table rather than assuming a built-in country rule.
How to use ABA Routing Checksum Validator and understand its results
- Gather verified caller country/notation requirements. Keep identifiers as strings so leading zeros survive; supply the applicable lookup table rather than assuming a built-in country rule.
- Enter routingNumberText using the field table and calculation rules, then run the tool.
- Read weightedRoutingChecksumMatches, checksumRemainder, nonzeroRoutingDigitsObserved. The explanation below defines the units, signs, ordering and any flags or placeholder values.
- If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.
| Input field | Meaning | Value type; see rules below | Requirement |
|---|---|---|---|
| routingNumberText | Routing number text | string | Required |
Enter exactly nine ASCII digits without trimming or a newline. Preserve zeros, apply repeating weights 3,7,1 and return match flag, remainder and a separate nonzero-digit flag. All zeros satisfy the checksum but make the nonzero flag false; malformed notation is an input error.
remainder=sum(digit_i×[3,7,1]_i) mod 10; matches=remainder=0 Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.
| Output field | Meaning | Value type |
|---|---|---|
| weightedRoutingChecksumMatches | Weighted routing checksum matches | boolean |
| checksumRemainder | Checksum remainder | number |
| nonzeroRoutingDigitsObserved | Nonzero routing digits observed | boolean |
{
"input": {
"routingNumberText": "021000021"
},
"output": {
"weightedRoutingChecksumMatches": true,
"checksumRemainder": 0,
"nonzeroRoutingDigitsObserved": true
}
}Limitations and assumptions
No directory assignment, prefix eligibility, bank identity or Fedwire participation is verified.
Numeric inputs, where present, must be finite. Follow the calculation-specific rules for overflow, underflow and exceptional cases. Extremely large text inputs are rejected. Missing fields without a declared default, extra fields, wrong value types and violations of the calculation rules are input errors. A successfully returned false flag is an evaluated outcome; its meaning is explained above.
Alternative or Complementary methods
Use Account Number Length Country Lookup: Account-number length is a country or bank policy rather than a universal account-validity test. Text preserves leading zeros. For a complementary task, use MICR Line Routing Account Parser: Parse bounded explicitly normalized MICR T-routing-T-account-U-serial-U notation, preserving zeros and checking routing checksum; not arbitrary MICR OCR, actual account validation, image recognition or complete vendor-specific layout support.
References
-
ABA Routing Checksum Validator — tool.io
Similar or alternative tools
- Account Number Length Country Lookup
Account-number length is a country or bank policy rather than a universal account-validity test. Text preserves leading zeros.
- MICR Line Routing Account Parser
Parse bounded explicitly normalized MICR T-routing-T-account-U-serial-U notation, preserving zeros and checking routing checksum; not arbitrary MICR OCR, actual account validation, image recognition or complete vendor-specific layout support.