Google Hreflang Guide: Syntax, Return Tags, and Testing

Hreflang (the rel=alternate hreflang annotation) tells Google which URLs are localized variants of the same page. Google can then choose a URL whose language and region better match the searcher. Hreflang is a signal, not a directive: it does not replace canonical URLs, indexability, or genuinely localized content.

Each localized URL should declare itself and its reciprocal alternates. If an English page points to a Spanish alternate, the Spanish page should point back to the English page. Invalid locale codes, missing return links, canonical conflicts, or alternate URLs that are not crawlable can cause Google to ignore the affected annotations.

Hreflang matters most for multilingual service businesses, cross-border companies, international ecommerce, and any site publishing equivalent pages for different languages or regions. A single-locale site does not need hreflang.

Hreflang uses the link rel=alternate attribute with an hreflang value. The value combines an ISO 639-1 language code with an optional ISO 3166-1 alpha-2 region code. Examples: en (English, any region), en-US (English United States), zh-CN (Chinese Simplified, Mainland China), zh-TW (Chinese Traditional, Taiwan), es-MX (Spanish Mexico), fil-PH (Filipino Philippines).

The hreflang value is case-insensitive to Google: zh-CN, zh-cn and zh-cN are treated the same. Writing region codes in uppercase follows the ISO convention and improves consistency. The actual requirement is to use valid language and region codes.

For each localized page, include a self-referential hreflang annotation and reciprocal annotations for the available language variants. The x-default annotation is optional and recommended when a fallback or language selector page is useful for visitors with unmatched languages; omitting it does not break hreflang.

Every alternate must be bi-directional. If page A (English) declares page B (Chinese) as its alternate, page B must declare page A as its alternate. Missing return tags is the most common hreflang mistake — Google ignores both directions when one is missing.

Mistake 1 — Invalid language or region codes, such as a region without a language or an unsupported region code. Google handles hreflang codes case-insensitively; uppercase region codes are an ISO formatting convention, not an indexing requirement. Fix unsupported codes, not harmless capitalization.

Mistake 2 — Missing return tags. Page A declares page B as alternate, but page B doesn't declare page A. Fix: every alternate must be bi-directional; if you add a new locale, update all existing pages to declare it back.

Mistake 3 — Choosing an unhelpful x-default fallback. x-default is optional; if you provide one, point it to a page that genuinely helps visitors whose languages are not listed, such as a language selector or appropriate default page. Missing x-default alone is not a hreflang error.

Mistake 4 — Hreflang URLs that don't match canonical URLs. If /pricing has canonical /pricing, but its hreflang points to /pricing?utm_source=internal, Google ignores the alternate. Fix: hreflang URLs must match canonical URLs character-for-character.

Mistake 5 — Hreflang on noindex or canonicalized-away pages. Pages blocked from indexing should not declare hreflang. Fix: omit hreflang tags on noindex routes, redirected routes, and pages canonicalized to other URLs.

Mistake 6 — Hreflang to soft-404 or 'locale not available' pages. Don't declare an alternate URL that returns a 'sorry, this page isn't available in your language' message — that's a soft 404 and Google penalizes both directions. Fix: only declare alternates that contain real content; if a page doesn't exist in a locale, don't declare that locale as alternate.

Mistake 7 — Inconsistent locale variants across pages. Page A declares locales en, zh-CN, es, but page B declares only en and zh-CN. Inconsistency confuses Google. Fix: every page that exists in multiple locales should declare all locales where it exists — and no locales where it doesn't.

Step 1 — Inspect the rendered HTML or sitemap annotations. Check valid language codes, the self-reference and reciprocal alternate URLs, and their crawlable destinations. Check x-default only if you chose to provide an optional fallback. Region-code capitalization is a readability convention, not a Google matching requirement.

Step 2 — Google Search Console. The former International Targeting report was deprecated in 2022. Use URL Inspection for individual indexing and canonical checks, and use the Performance report to review search results. Validate hreflang with a crawler or site audit, including return links, locale codes, and alternate URLs. Google still supports hreflang, but this old report is not available.

Step 3 — Ahrefs or Sitebulb crawl. These tools detect hreflang issues at scale — bi-directional tag mismatches across thousands of pages, broken alternates, incorrect locale codes. Run a full-site crawl quarterly.

Step 4 — Manual SERP test. Search for your brand name from different locale-specific devices (use a VPN or Google's country-specific domains like google.com.hk for Hong Kong) and verify the right locale version shows. If you see locale cannibalization (wrong version ranking in wrong region), hreflang is likely the cause.

Step 5 — Check indexing in Search Console. Use URL Inspection on each locale version of a page to confirm Google has indexed all alternates. If a locale version isn't indexed, hreflang isn't passing the signal correctly.

Best practice 1 — Use language-only codes (en, zh, es) when you don't have region-specific content. Use region codes (en-US, en-GB, zh-CN, zh-TW) only when content genuinely differs by region (currency, legal references, vocabulary). Over-specifying region codes when content is identical creates unnecessary alternates.

Best practice 2 — Consider an optional x-default for unmatched languages, especially for a language selector page. Choose the destination based on the experience you want users to have, not automatically the company's home-country language. A missing x-default does not invalidate valid hreflang alternates.

Best practice 3 — Generate hreflang from a single source of truth (your CMS or website builder). Hand-maintaining hreflang across thousands of pages guarantees drift. WordPress + WPML and Shopify's multilingual features both auto-generate hreflang; choose a builder that does.

Best practice 4 — Keep hreflang URLs clean and stable. Don't include query parameters, session IDs, or tracking parameters in hreflang URLs. Once an alternate URL is published, don't change it without a redirect — Google's hreflang cache takes weeks to rebuild.

Best practice 5 — Audit hreflang after every locale launch, locale removal, or major content migration. Drift happens; hreflang is the canary in the coal mine for multilingual site health.

Today, Cogo Site gives you multilingual content editing, AI translation drafts that you review, and a language switcher for your visitors.

Cogo Site does not yet generate hreflang tags or sitemap alternates for the sites you publish, and switching language does not change the page URL.

If your SEO plan depends on separate language URLs with hreflang, Cogo Site is not the right fit yet.