App Localization: Languages That Pay Off and How to Do It

Most apps ship with one store listing and quietly forfeit every shopper who browses in another language. This guide covers what the two stores let you localize as of October 2026, which languages are worth the money, the traps that waste it, and how to measure the result.

What the stores let you localize

On Apple's side, App Store Connect supports 50 metadata localizations after a 31 March 2026 expansion that added Bangla, Gujarati, Kannada, Malayalam, Marathi, Odia, Punjabi, Slovenian, Tamil, Telugu and Urdu, aimed at India ¹. Each of the 175 storefronts has a default language and often secondary ones: Germany defaults to German with English (U.K.) secondary, Japan to Japanese with English (U.S.), and the United States to English (U.S.) with nine extras including Spanish (Mexico), both Chinese scripts, Arabic, Korean, Portuguese (Brazil), Russian, French and Vietnamese ². What a shopper sees depends on the storefront, their device language and your primary language in App Store Connect ².

Google Play works on a language axis rather than a storefront axis. You add translations of the title, short description and full description, plus localized graphics, from the Store listing page ³. If a user's language has no translation, Play can show a machine translation with a banner, except in Armenian, Raeto-Romance, Tagalog and Zulu ³. Google's help page lists ten languages for free instant machine translation while its business site says 29; assume the smaller list until you see the picker in your own console ^3,4. Paid human translation costs from USD 0.07 per word, typically within seven days ³. Since I/O 2026 you can also upload a CSV or Google Sheet and have Gemini pre-fill listings across languages for review ⁵.

Both stores also offer audience-specific pages. Play allows up to 50 custom store listings targeted by country, traffic source or user state, but they are not auto-translated ⁶. Apple allows up to 70 custom product pages per app with their own screenshots, promotional text, previews, keywords and URLs, each localizable ⁷.

Which languages are worth it

Two signals matter: how many people a language reaches, and how much they spend. Ethnologue's 2026 edition puts total speakers (native plus second-language) at roughly 1.49 billion for English, 1.18 billion for Mandarin, 611 million for Hindi, 561 million for Spanish, 335 million for Modern Standard Arabic, 334 million for French, 274 million for Bengali, 269 million for Portuguese and 255 million for Indonesian ¹¹.

The spend side is lopsided. Sensor Tower counts about USD 167 billion of in-app purchase and paid app revenue across iOS and Google Play in 2025, with the United States alone near USD 60 billion ⁹. China's iOS storefront added about USD 22.1 billion, but Chinese Android stores sit outside Google Play ¹⁰. India led downloads with 25.5 billion installs in 2025, ahead of the US and Brazil, and Indonesia ranked second for time spent ¹⁰. Reach and revenue pull in different directions; the right order depends on whether you monetize with ads or purchases.

Where a language is secondary on Apple's table, the storefront defaults to English (U.K.), so an English listing already reaches those shoppers; the local language adds search coverage and conversion rather than visibility.

Keyword mechanics that catch people out

The App Store indexes a storefront's primary locale plus whatever secondary locales Apple attaches to it, and each activated locale carries its own keyword field ^12,13. That is why ASO teams fill Spanish (Mexico) and other US secondaries with English terms: on the US storefront those fields are searched too ¹². Apple does not combine words across locales, so a phrase must sit inside one localization, and repeating a keyword in several locales adds nothing ^12,13. The UK storefront lists no secondary locale, so English (U.K.) must carry everything ¹². This cross-indexing behaviour is documented by ASO vendors rather than by Apple, so verify it in your own account.

Google Play has no hidden keyword field; it indexes the listing text, and a localized listing reportedly needs around 10,000 installs in a locale before it ranks for local terms unconfirmed ¹³.

Common pitfalls

• Translating only text. Play falls back to default-language graphics when a translation has no localized assets ³, and Apple custom pages need their own localized screenshots ⁷.
• Machine output without review. Google says its free machine translation is instant but not reviewed by humans ³. Fine for a test market; not for your top five.
• Forgetting the fallback chain. A French-speaking Swiss user may see German or English (U.K.) depending on device settings ². Check the Swiss, Belgian, Canadian and Indian storefronts after every submission.
• Custom pages that ignore language. Play custom listings and Apple custom product pages both need translations added separately ^6,7.
• Treating English (U.K.) as optional. It is the default on most Apple storefronts, from Ireland and Singapore to most of Africa and Eastern Europe ².

Tools worth knowing

Inside the consoles: Play's translation ordering and Gemini-assisted CSV import ^3,5, and Apple's App Store Connect API for localized metadata ⁷. Outside them, ASO suites handle per-locale keyword research; the Aviasales team describes translating seed terms, mining autocomplete and reading competitor titles in each language before writing a localized title, subtitle and keyword set ¹⁴.

Measuring the lift

Vendor case studies are directional, not benchmarks. Komorebi's Roulette+ reported a 711% increase in App Store installs and about 6,000 daily downloads eight months after adding ten localizations including Mexico, Korea, Germany, Brazil and France ¹³. Aviasales reported roughly 54x growth after extending ASO to more than 30 languages, with no baseline disclosed ¹⁴. AppFollow cites a 26% conversion lift and download lifts up to 128%, but those measure different things and should not be stacked ¹³.

To measure your own lift, use the stores' experiments. Apple's product page optimization tests allow up to three treatments, run for at most 90 days, and let you choose which localizations participate; users in excluded localizations never enter the test ⁸. App Analytics reports impressions, downloads, conversion and retention per custom product page ⁷. On Play, compare per-country conversion before and after a translation goes live, and log the date, because ranking lags the listing change.

How this shows up in the charts

Top charts are computed per storefront, so localization pays out country by country. A listing that converts better in Brazil raises Brazilian download velocity, which is what the Brazilian Top Free chart measures; the US chart does not move. That is why localized apps often hold strong category positions in markets where they barely register at home, and why the biggest download markets, India and Brazil, have chart leaders that are not the US leaders ¹⁰. On AppWinners, compare an app's category rank across storefronts that share a language: if a Spanish-language app ranks in Mexico and Argentina but not Colombia or Chile, the listing is present but the keywords are not tuned, since all four default to Spanish (Mexico) ². Apple's eleven new Indic languages are likely to reshuffle India's charts over the next year as apps localized into Hindi, Tamil and Telugu pick up searches that English-only rivals cannot see ¹.