Hreflang for Bilingual Sites: Setting Up English and Thai Pages for Google
- What is hreflang and what does it do?
- Does your website need hreflang?
- How should you structure Thai and English URLs?
- How do you write hreflang tags?
- What is x-default?
- Which method should you use?
- What mistakes break hreflang?
- How do you check that hreflang works?
- Should you redirect visitors to a language automatically?
- How does DAB handle this?
- Need help with a bilingual website?
- FAQ
Hreflang is a tag that tells Google which language version of a page to show to which searcher. For a Thai and English website, pair each page with its translation, add hreflang links on both pages pointing to each other and to themselves, use the codes th and en, and keep every URL indexable.
Many Thai businesses run one website in English and Thai. Without hreflang, Google may show the English page to a Thai searcher, or the reverse. This guide explains what hreflang does, how to write it, how to check it and which mistakes break it.
Key takeaways - Hreflang tells Google which language version fits which searcher. It is a signal, not a command. - Every page in a pair must link to the other and to itself. - Use language codes: en for English, th for Thai. Add a region only if content differs by country. - Only pair pages that are real translations of each other. - Do not redirect visitors automatically by language. Let them choose.
What is hreflang and what does it do?
Hreflang is an annotation that tells search engines about alternate language versions of the same page. If your English page and your Thai page cover the same topic, hreflang links them. Google can then show the Thai version to someone searching in Thai and the English version to someone searching in English.
It does not directly raise rankings. It helps Google choose which of your pages to show, and it reduces confusion between versions. Google also reads the visible content to work out the language of a page, not the HTML lang attribute alone.
Does your website need hreflang?
You need it when:
- You publish the same content in English and Thai on separate URLs.
- Both versions are meant to be found in search.
You may not need it when:
- Your site is only in one language.
- The Thai pages are only partly translated. Pair only the pages that exist in both languages.
- You use a browser translation widget that does not create separate URLs, because there is nothing to link.
Translated pages are not duplicate content problems in themselves, but each version should be written for its readers and not machine translated without review.
How should you structure Thai and English URLs?
Google supports several structures, and each can work.
| Structure | Example | Notes |
|---|---|---|
| Subdirectory | example.com/th/ | Easy to manage on one WordPress site |
| Subdomain | th.example.com | Separate site area, more setup |
| Separate domain | example.co.th | Strongest country signal, more to maintain |
Whichever you choose, keep the pattern the same across the whole site. Thai or English URL slugs both work, but be consistent.
How do you write hreflang tags?
The most common method is to place tags in the head of each page. Both pages carry the same set of tags.
html
<link rel="alternate" hreflang="en" href="https://www.example.com/seo-services/" />
<link rel="alternate" hreflang="th" href="https://www.example.com/th/seo-services/" />
<link rel="alternate" hreflang="x-default" href="https://www.example.com/seo-services/" />
Rules to follow:
- Use full, absolute URLs.
- Include a tag for the page itself.
- Make sure each version links back to the others.
- Use valid codes: th for Thai, en for English. Add a country only if needed, such as en-GB. Note that en-UK is not valid.
- Each page's canonical tag should point to itself, not to the other language.
What is x-default?
The x-default value names the page to show when no language version fits the searcher, such as a language selector or your main version. It is optional but useful on bilingual sites.
Which method should you use?
You can add hreflang in the page head, in HTTP headers, or in your XML sitemap. Pick one method and use it consistently. For most business sites, the page head or the sitemap is the simplest. Many multilingual WordPress plugins add hreflang automatically, but always check the output yourself, because settings can be wrong.
What mistakes break hreflang?
| Mistake | Why it matters |
|---|---|
| Missing return links | Google may ignore the pair if each page does not reference the other |
| Pairing pages that are not translations | The signal becomes unreliable |
| Pointing to redirected, noindex or broken URLs | Google cannot use the annotation |
| Wrong codes such as en-UK or jp | The tag is not valid |
| Relative URLs | Can be misread |
| Canonical pointing to the other language | Conflicts with hreflang |
| Mixing several methods inconsistently | Creates conflicting signals |
How do you check that hreflang works?
- View the page source of the English page and confirm it lists both versions.
- Do the same for the Thai page and confirm it lists the same set.
- Open each listed URL and check that it loads without redirecting.
- Confirm each page is indexable and has a self-referencing canonical.
- Check a sample of pages from each template, such as service pages, articles and the homepage.
- In Search Console, use URL Inspection to see how Google treats a page, and watch search performance by country and language over time.
Should you redirect visitors to a language automatically?
No. Google advises against automatically redirecting people based on their perceived language or location, because it can stop search engines and visitors from reaching every version. Offer a clear language switcher and let people choose.
How does DAB handle this?
DAB's own website runs in English and Thai, and we have 18+ years of experience in web design and SEO in Bangkok. Our technical SEO services cover setup issues like this, and our web design services include building multilingual sites.
Need help with a bilingual website?
If your English and Thai pages are showing to the wrong audience, contact DAB through LINE or our contact page. Learn more about our technical SEO services in Thailand.
Related reading: how many pages a Thai business website needs and migrating or upgrading a website without losing SEO.
FAQ
Does hreflang improve rankings?
Not directly. It helps Google show the right language version to the right searcher, which can improve relevance and reduce wrong-language visits.
Should I use th or th-TH?
Use th if the page is simply in Thai. Use th-TH only if you also have a separate version for another region and need to separate them.
Can one URL contain both Thai and English?
It is better to give each language its own URL. Hreflang points to one URL per language version.
What if only some pages are translated?
Add hreflang only to the pairs that exist. Pages without a translation do not need hreflang.
Do I need hreflang if I use a translation widget?
Usually not. A widget that translates in the browser does not create separate indexable pages to link.