en vs en-US: when adding a region code helps and when it hurts

en vs en-US: when adding a region code helps and when it hurts

Hreflang lets you target language alone (en) or language plus region (en-US, en-GB). The instinct to always specify region is, we think, often wrong.

Methodology note: we compared clusters that used bare language codes against those that split by region, on sites with overlapping audiences.

Findings:

— Bare language codes (en, es, fr) win when content is genuinely identical across regions. Splitting into en-US and en-GB then forces you to maintain near-duplicate pages and creates needless return-tag surface area for errors.
— Region codes earn their keep only when content materially differs — currency, shipping, legal disclosures, spelling that affects search intent ('trousers' vs 'pants').
— A subtle trap: en-US and en-GB without an en or x-default fallback means a user in en-IN matches neither cleanly. Google picks by best fit, but you have surrendered control.

The data suggests over-segmentation is more common and more damaging than under-segmentation. Every region split doubles maintenance and multiplies reciprocity dependencies.

Our heuristic: start with language-only, add region codes only where a concrete content difference justifies a separate URL. Caveat: high-stakes regulated verticals (finance, pharma) may need region splits for compliance regardless of SEO economics.