# generaltranslation: General Translation Core SDK: standardizeLocale
URL: https://generaltranslation.com/en-US/docs/core/functions/locales/standardize-locale.mdx
---
title: standardizeLocale
description: API reference for the standardizeLocale function
---

## Overview

The `standardizeLocale` function standardizes a BCP-47 locale code to ensure correct formatting and casing without requiring a GT class instance.

```typescript
import { standardizeLocale } from 'generaltranslation';

// Fix common formatting issues
console.log(standardizeLocale('en_us')); // 'en-US'
console.log(standardizeLocale('zh_cn')); // 'zh-CN'
console.log(standardizeLocale('EN-gb')); // 'en-GB'
console.log(standardizeLocale('fr-ca')); // 'fr-CA'

// Already standardized locales pass through
console.log(standardizeLocale('es-ES')); // 'es-ES'
```

---

## Reference

### Parameters

<TypeTable
  type={{
    "locale": {
      type: 'string',
      optional: false,
    }
  }}
/>

### Returns

`string` - Standardized BCP-47 locale code or empty string if invalid

---

## Examples

### User input processing

```typescript
import { standardizeLocale, isValidLocale } from 'generaltranslation';

function processUserInput(input: string) {
  const standardized = standardizeLocale(input.trim());
  const isValid = isValidLocale(standardized);
  
  return {
    original: input,
    standardized,
    isValid
  };
}

// Test various inputs
const inputs = ['en_us', 'FR-ca', 'invalid', 'zh-CN'];
inputs.forEach(input => {
  console.log(processUserInput(input));
});
```

---

## Notes

- Converts underscores to hyphens
- Normalizes casing (language lowercase, region uppercase)
- Returns empty string for invalid formats
- Essential for normalizing locale input from various sources
- No external dependencies - pure string manipulation

## Next steps

- Use GT class method [`standardizeLocale`](/docs/core/class/methods/locales/standardize-locale)
- Validate with [`isValidLocale`](/docs/core/functions/locales/is-valid-locale)