Localization is one of the few growth levers where the upside is documented and the cost is contained. Studies put the download lift from localized app store presence at roughly 38% over English-only listings, localized listings alone have been measured lifting conversion by around 26%, and well-executed multi-market expansions have reported download increases well beyond that.
Those numbers are real, and they are also the reason founders make an expensive mistake: they translate the entire app into eight languages before knowing whether anyone in those markets wants it.
There is a much cheaper sequence. Here it is.
Localization has two halves, and they cost very differently
The store listing. Title, subtitle, keywords, description, screenshots. This is what determines whether someone in Germany searching in German ever finds you, and whether they install once they do.
The app itself. Every string, every screen, plus date formats, currency, text expansion breaking your layouts, and an ongoing obligation to translate everything you ship from now on.
The first is a weekend. The second is a permanent commitment. And critically, the listing is where most of the measured lift comes from, because it governs discovery and the install decision. A user who finds your app in their language and installs it will often tolerate an English interface, especially in markets with high English proficiency. The reverse is not true: a perfectly translated app that nobody in that market can find in search produces nothing.
So the sequence is: localize the listing, measure, and only then consider the app.
Let your own data pick the language
Most localization advice hands you a list of top-revenue languages. Japanese, Korean, Chinese, German, French are perennial Tier 1, Japan in particular generating several times more revenue per download than many large-population markets, and German users showing among the highest willingness to pay anywhere.
That list is useful context and a bad starting point, because it ignores you. A much better signal is already in your store console: where are your impressions coming from?
A widely used rule of thumb: if more than about 5% of your store impressions come from a non-English locale, that locale has earned its own properly localized listing. You are already being found there, by people using a language you have not written for, which means you are converting a fraction of what you could.
Check three things before picking:
- Impressions by country, to see where you already have organic visibility.
- Conversion rate by country, because a market with high impressions and low conversion is exactly the one a localized listing fixes.
- Revenue per user by country, which tells you whether the market pays.
The best first language is usually the intersection: meaningful existing impressions, weak conversion, decent spending power. That is frequently not the language at the top of the generic list.
Start with one, properly
The failure mode is breadth. Five machine-translated listings produce five mediocre presences and no clear read on whether localization works for you. One carefully done listing gives you a clean experiment.
Doing one properly means:
Real translation, not machine output alone. Machine translation has improved enormously and is a reasonable first draft, but a native speaker should review anything users see. Store listings are marketing copy, and marketing copy translated literally reads wrong in ways that quietly cost conversion.
Localized keywords, not translated ones. This is the part most people get wrong. Your target users in a new market do not search for the direct translation of your English keyword; they search for whatever phrase is idiomatic there. Research the keywords natively, the same way you did in English: autocomplete, competitor listings, the words people actually use in that market's communities.
Localized screenshots. The captions carry both the conversion message and, on iOS, indexable text. Screenshots in English with a translated description is a half measure that looks unfinished.
Cultural fit, not just language. Imagery, colour associations, what counts as a credible claim, and even how direct the copy should be all vary. The largest documented conversion gains come from culturally adapted listings, not literal translations.
Then measure over a real window
Give it 60 to 90 days before judging. You are looking for:
- Impressions in that locale rising as you rank for local keywords
- Conversion rate in that locale improving against its own pre-localization baseline
- Installs and revenue from the market, net of any acquisition spend
Compare the locale against itself before and after, not against your English numbers, which reflect a different market entirely.
If the listing moves the numbers, you have learned that this market responds, and you can then decide whether to localize the app itself for it. If it does nothing, you spent a weekend and learned something cheap. Either outcome is a good use of the effort.
When to localize the app itself
Only after a listing has proven the market. Even then, consider the ongoing cost honestly: every feature, every onboarding change, every error message becomes a translation task forever, and a partially translated app is a worse experience than a consistently English one.
Signals that it is worth it:
- The localized listing produced real installs, and retention in that market is comparable to your home market
- The market is one where English proficiency is low enough that the interface is a genuine barrier
- Support requests arrive in that language, which tells you people are pushing through a barrier to use your product
Also worth knowing: the biggest gains generally come from markets you have invested nothing in, not from doubling down where you already have visibility. Localization is most valuable as a way of opening a new door, not polishing an open one.
The honest caveats
Support becomes multilingual. You will get support emails in the new language. Decide in advance how you will handle that, even if the answer is a machine-translated reply with an honest note that you are one person.
Reviews become multilingual. Your rating is per-market, and so are the complaints. You need a way to read them.
Low-cost markets can flatter your download numbers and hurt your unit economics, especially if you are running paid acquisition. Judge new markets on revenue and retention, not installs.
Some categories do not travel. If your app is built around a country's specific rules, culture, or institutions, the content may not port even if the language does.
The one-weekend version
If this feels like a lot, here is the minimum:
- Open your store console and find the top non-English locale by impressions.
- If it is above roughly 5% of impressions, pick it.
- Get the title, subtitle, keywords, description, and screenshot captions properly translated and natively keyword-researched.
- Ship the listing. Change nothing else.
- Look at that locale's conversion rate in 60 days.
That is the whole experiment, and it costs a weekend plus a modest translation fee. Compared with most growth work available to a small app, the ratio of effort to potential upside is unusually good, which is precisely why it is worth doing deliberately instead of all at once.
Originally published at https://foundyra.com/news/app-localization-first-languages
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