ABA routing number checker

Client

United States routing transit numbers are nine digits with a published MICR checksum and routing-symbol prefixes. Paste digits to see pass/fail plus an optional Federal Reserve district hint—no directory proves an institution is still active.

Scope

International payments typically use IBAN; US ACH and domestic wires still rely on these routing numbers alongside separate account numbers.

What this checks

ABA routing transit numbers are nine digits with a published weighted checksum. This page confirms the digit chain—not whether the institution is active or accepts ACH.

Sensitive identifiers: validating routing numbers still exposes banking metadata—keep samples non-production on shared machines even though nothing uploads from this tab.
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Nine digits after stripping separators. Weights cycle 3, 7, 1 across positions—the sum must be a multiple of 10. District blurbs reference common Fed routing-symbol prefixes only.

9 digits → compact 021000021

MICR checksum: passes — still verify against your ACH provider before moving money.

Routing symbol 02 often corresponds to the Federal Reserve Bank of New York district (reference table only).

Nearby workflows on Toolcore

  • IBAN validate — for cross-border wires that list both RTN and IBAN columns.
  • BIC / SWIFT format — when messages also carry an eight- or eleven-character BIC.

Common use cases

  • Double-check a routing string before wiring it into ACH onboarding fixtures next to your processor docs.
  • Explain to peers why a pasted transit number fails checksum without calling an external bank API.
  • Pair with IBAN validate when a ticket mixes EU IBANs and US ACH routing numbers.

Common mistakes to avoid

  • Confusing routing numbers with account numbers

    Only the nine-digit routing/transit field belongs here—account numbers use separate checksum rules (if any).

  • Assuming a passing checksum proves bank routing

    Checksum weeds out many typos; retired numbers or institution merges still require issuer confirmation.

FAQ

Does this hit an ACH or bank API?

No. The math runs locally in your browser tab.

What checksum formula is used?

The MICR routing-number formula: multiply digits by repeating weights 3, 7, 1 from left to right and require the weighted sum to be divisible by 10.

Is the Fed district text authoritative?

It summarizes commonly published routing-symbol prefixes for education—always reconcile with current ABA references when compliance matters.

Common search terms

Phrases people search for that match this tool. See the full long-tail keyword index.

  • aba routing number validator online
  • bank routing number checksum micr
  • fed routing transit number check browser
  • ach wire routing number format validate locally

More tools

Related utilities you can open in another tab—mostly client-side.