There are over 8 billion people on our planet, and roughly 1.5 billion of them speak English — approximately 19%. Of those 1.5 billion, less than 400 million are native English speakers.

That means there’s a theoretical maximum 500% increase in your total addressable market (20% of the market speaks English, 20% → 100% is a 5x increase) simply by localizing your application. The actual increase will, of course, be something lower than that theoretical maximum — not everyone everywhere who speaks every language is a potential user of your service — but I do think it’s a good point of reference for those of us in the English-centric world to begin understanding the magnitude of the opportunity.

What the Data Says

Theory is fun, but what does real-world data tell us? Unfortunately, high-quality data, as I would define it, is scant. CSA Research is one of few independent organizations focused on actionable globalization research. Some of their findings:

• 75% of potential customers will immediately look elsewhere if content is not in their language
• 40% of consumers flatly refuse to purchase in any language other than their native language
• Some of their research shows that each dollar spent on localization enables 5.8 times as much revenue as would that same spending on English. Meaning that rather than advertise more to English customers, create more English content, etc., if that money were spent on localizing existing content/advertising you would see a 5.8x better return.
  • I read more deeply into their research backing this specific claim, and it’s very theoretical, to say the least. While I do think it has enough merit to mention here, I would take it with a large grain of “every industry/product/service/market is different” salt.

How can we validate?

Before diving headfirst into localizing all of our content everywhere in all of our web and mobile applications, marketing sites, branding, and content marketing channels, validating the potential value of this opportunity on a smaller scale is a great starting point.

Customer Interviews

Continually interviewing customers is a best practice in general, and before embarking on localization can be a great way to get some initial data. What can be especially valuable is finding potential customers who are from non-English speaking countries and did not end up using your software. Hopefully, you already have some data collection in place that allows you to determine users’ approximate location and, with a bit of data wrangling, generate a list of those users who did not end up as paying customers. Interview them with an eye toward localization.

Marketing Site

Localizing your marketing site is, in most cases, going to be much easier, faster, and cost-effective than localizing your applications. If you happen to have built your marketing site using a tool like Webflow or Framer, a small team can localize your site in multiple languages in a week or two. If your marketing site is built and maintained by your engineering team, it’s certainly a more involved project, but it is much smaller in scale than localizing applications.

Remember to measure what matters. Ideally, you’ll be able to compare conversion rates of non-English visitors before and after localization.

Essential in the B2C World

If your software is primarily targeted toward individual consumers, I would suggest that localization is almost essential. Recall that 6.5 billion people, 80% of the world’s population, don’t understand English. You’re likely missing a huge opportunity there if you don’t localize. Discovery and validation due diligence is certainly warranted, but if your app is only available in English it’s an opportunity I would prioritize researching.

B2B: Test and Validate

English is undoubtedly the de facto language in the B2B SaaS world. Companies around the world expect to use software tools in English, even in cases where many of their employees don’t speak the language. I would suggest interviewing and small-scale tests to validate whether internationalization is currently a top-priority opportunity your company should pursue, keeping in mind that this opportunity is only going to grow over time as internet access and incomes around the world increase.

Tools and Strategies for Application Localization

I want to briefly touch on an overarching strategy for localizing your software applications, one I’ve used in production. Fortunately, over the past decade there have been some incredible advances that make it much easier and cost-effective to localize. Let’s consider an example company that has both a React web and React Native mobile application.

React/React Native Localization Frameworks

You’ll first need a localization framework for your applications. The general idea is that your framework will help you extract all of the strings in your application to some centralized store, from which you can translate each string.

As of 2025, my personal recommendation is Lingui, but take a look at react-i18next and react-intl. Lingui takes a different approach, which I think makes localization for your engineering team much smoother; rather than a JSON string approach, you use React components and hooks. It’s a clever approach that has many benefits over legacy solutions.

Translation Management System (TMS)

Second, you’ll need a way to actually translate each string that your framework extracted.

Small teams and open-source projects may choose to do this manually, but a translation management system makes doing this much more scalable. In a nutshell, as strings are added to your application (or original language strings are modified), you’ll git push those strings to a TMS. Within the TMS, you can choose between a combination of machine learning, AI, and real translators to translate each string. When the translation is finished, you git pull those translations back into your project.

A good 10,000-foot view is that your app itself is the source of truth for your strings in the original language (probably English, if you’re reading this article), and the TMS is the source of truth for the translated strings.

International Markets Will Continue to Grow

Internet access and incomes around the world continue to grow. As developing countries climb the economic ladder, more and more consumers and companies within those countries will become potential users of your products. Will you be ready to onboard them?