About

Billing address validation failures cause 3 - 8% of e-commerce transaction declines. Payment processors cross-reference the postal code field against the card issuer's records using AVS (Address Verification System). A misformatted code - wrong length, invalid prefix, or illegal characters - triggers an immediate reject before the charge even reaches the bank. This tool generates structurally valid postal codes conforming to each country's format specification: 5-digit numeric for US ZIP codes with state-aware prefix ranges, alphanumeric ANA NAN patterns for Canadian FSA/LDU codes, and outward/inward splits for UK postcodes. Use it to populate test environments, QA billing forms, or validate regex patterns against real format constraints.

Generated codes follow documented format rules from Universal Postal Union (UPU) standards. They are syntactically correct but do not guarantee geographic existence. For US codes, prefixes map to valid state ranges (e.g., 100 - 149 for New York). Canadian codes exclude letters D, F, I, O, Q, U per Canada Post rules. UK codes respect the area letter system. This is test data generation, not a geocoding service. Confirm real-world deliverability through your postal authority's API.

Formulas

Postal code generation follows a format-template approach. Each country defines a pattern string where N represents a random digit (0 - 9) and A represents a random uppercase letter (A - Z). For constrained countries, prefix ranges narrow the randomization space.

code = map(format, char →

{

randInt(0, 9) if char = "N"randLetter(allowed) if char = "A"char otherwise (literal)

)

For region-aware generation (e.g., US ZIP codes), the first k digits are sampled from a valid prefix range:

prefix = randInt(range_min, range_max)

Where range_min and range_max are the lowest and highest valid prefix values for the selected state or region. Remaining digits are filled with uniform random values. The function randInt(a, b) uses crypto.getRandomValues for uniform distribution across [a, b].

Canadian codes exclude the letters {D, F, I, O, Q, U} from all positions, and further restrict the first character to valid FSA letters per province. Dutch codes exclude letter combinations SA, SD, SS from the suffix.

Reference Data

Country	ISO Code	Format	Example	Length	Notes
United States	US	NNNNN	10001	5	State-prefixed ranges
United Kingdom	GB	A9 9AA / A99 9AA / AA9 9AA	SW1A 1AA	6-8	Outward + Inward codes
Canada	CA	A9A 9A9	M5V 2T6	7	No D, F, I, O, Q, U
Germany	DE	NNNNN	10115	5	Range 01001-99998
France	FR	NNNNN	75001	5	Dept prefix (01-95, 2A/2B)
Australia	AU	NNNN	2000	4	State-based ranges
Japan	JP	NNN-NNNN	100-0001	8	Hyphenated 3+4 digits
India	IN	NNNNNN	110001	6	First digit = region (1-8)
Brazil	BR	NNNNN-NNN	01001-000	9	Hyphenated 5+3 digits
Netherlands	NL	NNNN AA	1011 AB	7	No SA, SD, SS
Italy	IT	NNNNN	00100	5	Range 00010-98168
Spain	ES	NNNNN	28001	5	Province prefix 01-52
Sweden	SE	NNN NN	111 22	6	Space-separated
Norway	NO	NNNN	0101	4	Range 0001-9991
Switzerland	CH	NNNN	8001	4	Range 1000-9658
Poland	PL	NN-NNN	00-001	6	Hyphenated
Portugal	PT	NNNN-NNN	1000-001	8	Hyphenated 4+3
Belgium	BE	NNNN	1000	4	Range 1000-9992
Austria	AT	NNNN	1010	4	Range 1010-9992
Denmark	DK	NNNN	1000	4	Range 0800-9990
Finland	FI	NNNNN	00100	5	Range 00100-99999
Ireland	IE	A99 A9A9	D02 AF30	7	Eircode format
Czech Republic	CZ	NNN NN	100 00	6	Space-separated
South Korea	KR	NNNNN	03051	5	Range 01000-63644
Mexico	MX	NNNNN	01000	5	Range 01000-99998
Russia	RU	NNNNNN	101000	6	Range 101000-999999
China	CN	NNNNNN	100000	6	Range 100000-999999
Singapore	SG	NNNNNN	018956	6	Range 010000-828888
South Africa	ZA	NNNN	2001	4	Range 0001-9999
New Zealand	NZ	NNNN	6011	4	Range 0110-9893
Argentina	AR	ANNNNAA	C1043AAQ	8	CPA format

Frequently Asked Questions

No. Generated codes are syntactically valid - they conform to the country's format rules, length, and character constraints. However, they are not guaranteed to correspond to a real geographic location. For US ZIP codes, the prefix maps to a valid state range, but the full 5-digit code may not be assigned by USPS. Use these for testing billing form validation, not for mailing.

AVS compares the billing postal code submitted during a card transaction against the code on file with the card issuer. It returns match codes: Y (full match), N (no match), P (partial), or U (unavailable). A structurally invalid code - wrong length, illegal characters - causes an outright processing error before AVS even runs. This tool ensures the format passes the structural check.

Canada Post excludes the letters D, F, I, O, Q, and U to prevent visual confusion with digits (0, 1) and other letters. Additionally, the letters W and Z are never used as the first character of the Forward Sortation Area (FSA). This generator enforces both rules. The first character is drawn from a set of valid FSA letters mapped to provinces.

A standard US ZIP code is 5 digits (e.g., 10001). ZIP+4 appends a hyphen and 4 additional digits (e.g., 10001-7050) that narrow delivery to a specific block or building. Most billing systems only require the 5-digit ZIP. This generator produces 5-digit codes. The +4 suffix is rarely validated by payment processors.

UK postcodes have two parts: the outward code (area + district, e.g., SW1A) and the inward code (sector + unit, e.g., 1AA). The area is 1-2 letters, the district is 1-2 digits (sometimes with a trailing letter). The inward code is always a digit followed by two letters. Letters C, I, K, M, O, V are excluded from the final two positions. This generator respects all these constraints.

Yes, that is a primary use case. Payment gateway sandbox environments (Stripe test mode, PayPal sandbox) accept structurally valid postal codes. Using correctly formatted codes ensures your tests exercise the full validation pipeline. Invalid formats would be rejected at the input validation layer, never reaching the gateway, which defeats the purpose of integration testing.

Alphanumeric codes (UK, Canada, Ireland, Netherlands, Argentina) encode more information per character. A single alphanumeric position has 36 possible values versus 10 for numeric. This allows shorter codes to cover more addresses. Canada's 6-character alphanumeric code (A9A 9A9) can represent approximately 7.2 million unique combinations after letter exclusions. A purely numeric code would need 7+ digits for equivalent coverage.