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DUNS Number Validator

Finance & Global IDs

Validate a Dun & Bradstreet DUNS number format instantly. Checks 9-digit structure and formats as XX-XXX-XXXX. Free, client-side, no data stored.

Reviewed by the thecalcu.com team · Last updated July 31, 2026

What is a DUNS?

The DUNS Number Validator checks whether a D-U-N-S Number follows the correct format: exactly 9 digits, entered in either plain form (123456789) or the standard hyphenated display format (12-345-6789). It also shows the formatted output for copy-and-paste into forms and procurement systems.

A DUNS number (Data Universal Numbering System) is a 9-digit business identifier assigned by Dun & Bradstreet to uniquely identify business entities in their global commercial database. Established in 1963, DUNS numbers are used in US federal government procurement (SAM.gov, USASpending.gov), global supply chain management, international trade finance, and business credit reporting.

Unlike identifiers such as the Routing Number or EIN, the DUNS has no public checksum algorithm, D&B assigns numbers from an internal sequential database. Format validation (9 digits, no letters) is therefore the only client-side check possible without a D&B API call.

What this validator checks: exactly 9 digits, no alphabetic or special characters (hyphens are accepted as separators and stripped before checking).

What it does not check: Whether the specific 9-digit number is assigned to a real business in D&B's database. That requires a D&B lookup.

All validation is client-side. No data is transmitted.

Why Use a DUNS Number Validator?

US federal procurement forms, ERP supplier onboarding workflows, and corporate vendor management systems all require DUNS numbers. Users frequently enter incorrect formats, 8-digit numbers, numbers with letters, or numbers with extra characters copied from formatted documents.

Government contracting use case: An Indian IT company registering in SAM.gov for US federal contracting must enter its DUNS number. A validator at the form level flags 8-digit entries (missing a digit) or 10-digit entries (extra digit from a formatting error) before submission, preventing a failed SAM.gov registration.

Procurement use case: A US Fortune 500 company's vendor onboarding portal requires suppliers to enter their DUNS number. A format validator catches obviously incorrect entries (wrong digit count) before they reach the D&B verification API, reducing unnecessary API calls and improving form UX.

Who Should Use This Validator?

Indian IT companies preparing for US federal contracting registration (SAM.gov) who need to verify their DUNS number format before submission.

Procurement and supply chain teams at companies that require DUNS numbers from suppliers during vendor onboarding.

Developers building US government contracting or ERP vendor management systems that collect DUNS numbers as part of supplier data.

Finance and accounting teams at Indian companies with US operations who manage supplier and contractor records including D&B DUNS identifiers.

What Insights Does the DUNS Number Validator Give You?

A valid result shows both the plain 9-digit DUNS and the standard XX-XXX-XXXX hyphenated display format. The display format note clarifies that no public checksum exists, only format (9 digits) can be validated without a D&B API.

An invalid result specifies the failure: wrong digit count or non-digit characters. The most common error is entering 8 digits (a digit was accidentally omitted).

How to use this DUNS calculator

  1. Enter the DUNS number in the input field, plain digits (123456789) or hyphenated (12-345-6789).
  2. Check the Valid/Invalid badge, updates instantly.
  3. Read the formatted output, the details panel shows the standard XX-XXX-XXXX display format.
  4. Copy the formatted DUNS for use in SAM.gov or supplier onboarding forms.
  5. Confirm assignment: for active business verification, search dnb.com or SAM.gov.
  6. Related tools: use the EIN Validator for US employer identification numbers.
Show formula & methodology ↓Show less ↑

Formula & Methodology

Format rule:
- Strip hyphens and spaces
- Remaining characters must be exactly 9 digits (0–9)
- No publicly documented checksum, D&B assigns numbers sequentially

Display format:
XXXXXXXXX → XX-XXX-XXXX 123456789 → 12-345-6789

Valid and invalid examples:

| Input | Valid? | Note |
|---|---|---|
| 123456789 | ✓ | 9 digits, correct format |
| 12-345-6789 | ✓ | Hyphenated format, strips to 9 digits |
| 12345678 | ✗ | Only 8 digits |
| 1234567890 | ✗ | 10 digits, extra digit |
| 12-345-678A | ✗ | Non-digit character |

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Frequently Asked Questions

What is a DUNS number?
A DUNS number (Data Universal Numbering System) is a unique 9-digit identifier assigned to business entities by Dun & Bradstreet (D&B). It was created in 1963 and is used worldwide to identify and track businesses in D&B's global commercial database. DUNS numbers are used for business credit reports, supplier identification, US federal government contracting, and business-to-business transactions. The identifier is also known as the D-U-N-S Number.
Why do US government contractors need a DUNS number?
US federal government regulations require vendors and contractors to register a DUNS number in SAM.gov (System for Award Management) before receiving federal contracts or grants. The requirement applies to all prime contractors and most subcontractors. DUNS numbers allow federal procurement systems to identify business entities, track their past performance, and perform due diligence. Note: as of April 2022, the US federal government began transitioning from DUNS to the UEI (Unique Entity Identifier) system, but DUNS numbers remain widely used in non-government commercial contexts.
What is the format of a DUNS number?
A DUNS number is exactly 9 digits. The common display format is XX-XXX-XXXX (with hyphens), though plain 9-digit format (without hyphens) is also used interchangeably. There is no publicly documented checksum algorithm, D&B assigns numbers sequentially from their internal database.
Does this validator confirm the DUNS is assigned to a real business?
The validator checks format only: exactly 9 digits (with or without hyphens). It does not query D&B's database to confirm the DUNS is assigned to an active company. To verify a DUNS is registered to a specific business, use D&B's free company search tool at dnb.com, or search SAM.gov for registered federal contractors.
How do I get a DUNS number for my business?
DUNS numbers are free to obtain. US businesses can apply at dnb.com or call D&B directly. The process typically takes 1–5 business days. Indian companies that do business with US federal agencies or large US corporations also need DUNS numbers, the application process is the same globally. Businesses in the US federal contracting pipeline can apply through SAM.gov as part of the registration process.
What is the difference between a DUNS number and a UEI?
The UEI (Unique Entity Identifier) replaced the DUNS number as the required identifier for US federal government contracting as of April 2022. UEIs are issued by SAM.gov rather than D&B. However, DUNS numbers remain the standard identifier in D&B's global business credit database, private sector supply chains, and many international procurement systems. Many organisations use both identifiers.
Is my DUNS data stored when I validate it?
No, all validation runs entirely in your browser. The DUNS number is never sent to any server, stored, or logged. The tool works offline once loaded.
Can an Indian company have a DUNS number?
Yes, D&B assigns DUNS numbers to businesses worldwide, not just US companies. Indian companies that supply to US multinationals, participate in US federal contracting through their subsidiaries, or operate in global supply chains often have DUNS numbers. Indian companies can apply for a DUNS number through D&B India's website.
How do I use the DUNS Number Validator?
Enter the DUNS number in the input field, either in the XX-XXX-XXXX hyphenated format or as plain 9 digits. Hyphens are stripped automatically. The validator checks that exactly 9 digits remain. The Valid/Invalid badge updates instantly. For a valid DUNS, the details panel shows both the plain 9-digit format and the standard XX-XXX-XXXX display format.
What is the difference between a DUNS number and an EIN?
A DUNS number is assigned by Dun & Bradstreet, a private company, for business identification in credit and procurement databases. An EIN (Employer Identification Number) is assigned by the IRS for US tax purposes. A US business may have both, the EIN identifies the business for tax filings; the DUNS identifies the business in D&B's credit and procurement database. Non-US businesses can have a DUNS without having a US EIN. Use the [EIN Validator](/ein-validator/) to check an EIN.
What happens if I enter a 9-digit number that is not an assigned DUNS?
The validator will show Valid, because 9 digits is a structurally valid DUNS format. The validator cannot tell whether a specific number is currently assigned to a business in D&B's database. To confirm assignment, search for the number on dnb.com. A number that passes format validation but is not in D&B's database is simply unassigned.
Also known as
DUNS number checkD-U-N-S validatorDun Bradstreet numbervalidate DUNSDUNS lookup format