Locale Code
A locale code is a short identifier (like en-US, de-DE, ja) that tells the App Store or Google Play Console which market and language a piece of content belongs to. Apple and Google use slightly different formats.
A locale code is the technical identifier that pairs a language with an optional region, telling App Store Connect and Google Play Console which market and translation an asset belongs to. Both stores build on ISO 639-1 language codes and ISO 3166-1 country codes, but their conventions diverge. Apple uses a fixed set of localization slugs (en-US, en-GB, es-MX (which serves all of Latin America), es-ES, pt-BR, pt-PT, script codes zh-Hans and zh-Hant, and bare codes like ja and ko. Google Play uses BCP-47 tags and expects es-419 for Latin American Spanish where Apple expects es-MX, and zh-TW where Apple uses zh-Hant. Apple currently supports roughly 40 App Store localizations. The code you attach to a screenshot set, keyword field, or description is what routes that content to the right storefront), and a missing one silently falls back to your app's primary language.
Why It Matters
Locale codes are the routing layer of localization, and their failures are silent. There is no error message, just lost conversions. Tag Brazilian screenshots as pt-PT and every Brazilian shopper sees your default primary-language page while Portuguese users read subtly wrong phrasing. Choose es-ES when your market is Mexico and 100M+ Latin American users miss your translation entirely. Because Apple and Google diverge (es-MX vs es-419, zh-Hans vs zh-TW), a code that validates in one console breaks in the other. Getting the code right is the precondition for every downstream localization dollar (translation, screenshot design, ASO keywords) to actually reach a human instead of evaporating into a fallback.
Example
A gaming studio localizes into three Spanish-speaking markets. On Apple they upload one es-ES set (1320×2868 iPhone 17 Pro Max screenshots) for Spain and one es-MX set for all of Latin America, because Apple routes the Mexico, Argentina, and Colombia storefronts through es-MX. On Google Play they replicate the Spain set as es-ES but must use es-419 (not es-MX) for the same Latin American reach; es-MX on Play would only cover Mexico. They also discover Traditional Chinese must be zh-Hant on Apple but zh-TW on Google. One asset library, three different code conventions, and any single mismatch drops that market back to the English default.
Frequently Asked Questions
Are App Store and Google Play locale codes the same?
Both build on ISO 639 language and ISO 3166 country codes, but conventions differ. Apple often uses a bare language code (ja, ko) plus script codes (zh-Hans/zh-Hant), while Google Play uses BCP-47 tags that need region pairs like zh-TW and es-419. Latin American Spanish is es-MX on Apple but es-419 on Google. Always verify against a lookup rather than assuming parity between the two stores.
Do I need to support every locale my app supports?
No. Start with the locales where you actually plan to drive traffic or expect organic visibility. Localizing into a market you have no campaign or demand for is usually wasted work. It is better to fully localize five high-value storefronts (screenshots, keywords, and description) than to half-localize twenty.
What happens if I use the wrong locale code?
Your localized assets attach to the wrong market or silently fail to attach at all. Users in the intended market see your default primary-language content instead. There is no error message and no rejection. Just a quiet drop in conversion in that storefront that is easy to miss without per-locale analytics.
What locale code covers Latin American Spanish?
On Apple it is es-MX. A single localization that serves every Spanish-speaking Latin American storefront, so you do not upload a set per country. On Google Play it is es-419, the BCP-47 tag for Latin American Spanish. Neither store uses a generic "es-LatAm," and es-ES stays reserved for Spain on both.
How many App Store localizations does Apple support?
Apple currently offers roughly 40 App Store localizations, from en-US and de-DE to th (Thai), vi (Vietnamese), and zh-Hans/zh-Hant. You designate one as your app's primary language, and that becomes the fallback shown whenever a user's storefront locale has no dedicated screenshots, keywords, or description.
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