Beyond the basics: Navigating language codes for true localization

We’ve all seen the two- or three-letter abbreviations representing languages. These language codes, such as "en" for English or "es" for Spanish, are the foundation of any localization strategy. Most developers and product managers are familiar with the language codes from the ISO 639 standard, released by the International Organization for Standardization (ISO). They are the world's most frequently used linguistic codification system, and they play a crucial role in everything from language recognition to training neural learning models.

While these two-letter language codes (ISO 639-1) and their three-letter counterparts (ISO 639-2, ISO 639-3) provide an important starting point, relying on them alone can sometimes create an incomplete or awkward user experience. To build a truly global product, it’s not enough to simply speak a language; you also need to speak the correct dialect in the right way. This is where regional and dialect-specific codes become essential, allowing you to tailor experiences that resonate with your target audiences.

Why simple language codes aren’t enough

Imagine launching your app in English. Do you simply tag it as "en"? This generic code applies to a wide range of users, from New York to London to Sydney. While they speak English, their spelling, vocabulary, and cultural nuances can be surprisingly different.

• Spelling: "Color" (en-US) vs. "colour" (en-GB)

• Vocabulary: "Trunk" of a car (en-US) vs. "boot" (en-GB)

• Dates and Currency: The formatting of dates and the display of currency can vary significantly.

This problem is even more pronounced with languages like Spanish. A generic "es"-tag could apply to speakers in Spain, Mexico, Argentina, or Colombia. Each region has its own idioms, slang, and cultural context. A literal translation that works in one country might sound strange or even offensive in another. That’s why having a robust translation memory and carefully managed terminology is critical to handling these variations without re-translating everything from scratch.

Understanding the granularity of ISO 639

The ISO 639 standard provides different levels of granularity for managing languages:

• ISO 639-1: two-letter language codes that cover the world’s major languages

• ISO 639-2 and 639-3: three-letter codes that expand coverage and specificity

• IETF BCP 47: a standard that builds on ISO codes by combining them with regional identifiers to distinguish dialects and regional usage

We’ve written an extensive guide about ISO language codes in the past.

For example:

• en-US: English as spoken in the United States

• en-GB: English as spoken in Great Britain

• es-ES: Spanish from Spain

• es-MX: Spanish from Mexico

These regional tags ensure your content isn’t just translated but truly localized. They tell your software which spelling rules, date formats, and cultural nuances to display. A slight tweak in code makes a big difference for users.

When to use specific language ISO codes

There are many situations where you should go beyond a basic code and use a precise ISO language code with regional identifiers:

• When your product contains cultural references: Apps with slang, idioms, or references to region-specific holidays must use the right code to avoid misunderstandings.

• For eCommerce and financial platforms: Correct currency symbols, decimal separators, and date formats to build trust and improve usability. A user in Germany expects to see “€” and commas as decimal separators, while users in the U.S. expect “$” and periods.

• When one language has significant dialectal differences: Spanish (es-ES vs. es-MX), Portuguese (pt-BR vs. pt-PT), and Chinese (zh-Hans vs. zh-Hant) are classic examples where generic tags fail.

• When using artificial intelligence in translations: Even our powerful AI agent, LINA, relies on these granular codes. The more specific the tag, the better the terminology and tone of your output will be.

Managing language codes at LingoHub

Handling multiple language ISO codes across different projects can feel overwhelming, especially when dozens of variants come into play. That’s why LingoHub provides full support for all ISO 639 language codes, ensuring you have the proper framework for global projects of any scale.

Our translation management platform was built to simplify complexity. With Language Code Support, you can access clear guidelines that help you make the best localization choices for each project. Our regularly updated Language Designators List makes finding the exact code you need simple, whether a two-letter abbreviation or a more granular regional variant. And if you ever feel uncertain about which code to use, our support team is always ready to guide you toward the right solution.

By weaving language ISO codes directly into your localization workflow, LingoHub ensures that projects are accurate and consistent across regions. With features like team assignments, style guides, and translation memory management, our TMS helps you confidently handle even the most granular dialectal differences.

From "translated" to truly "localized"

Moving beyond generic tags and embracing the full depth of ISO 639 language codes elevates your product from simply “translated” to genuinely “localized.” This level of precision shows users you care about their specific needs, whether they’re in Madrid, Buenos Aires, or Mexico City. It also reduces rework, improves machine translation output, and fosters trust by delivering familiar experiences that feel native.

LingoHub makes this process effortless by combining robust code support, intuitive tools, and hands-on guidance. Our platform streamlines your localization workflow, making your product more accessible and enabling your users to feel genuinely at home. Investing in accurate language ISO codes is not just a technical detail; it’s a powerful way to enhance user satisfaction, foster brand loyalty, and expand global presence.

Book a demo now and experience the power of our robust translation management software.