Portuguese
How to get natural Portuguese out of Syntic models, and what to check before you ship. The general rules for every language are on Work in other languages.
At a glance
| Language tags | pt-BR (Brazil), pt-PT (Portugal) |
| Script and direction | Latin script, left to right |
| Token use | Measure with token counting on your own text; non-Latin scripts and long compounds usually take more tokens per sentence than English. |
Register and form of address
Brazilian and European Portuguese differ in vocabulary, spelling of some words and, most visibly, in address: você is standard in Brazil, while Portugal often uses o senhor/a senhora or third-person forms for formal contact. Always pick a variety.
Numbers, dates and currency
Decimal comma (R$ 12,50 / 12,50 €). Dates: 5 de novembro de 2026, 05/11/2026.
Common pitfalls
- Vocabulary pairs: ônibus/autocarro, celular/telemóvel, tela/ecrã. Getting these wrong marks the text as foreign.
- Gerund usage (estou fazendo vs estou a fazer) is a reliable tell of variety; check it in evaluation.
A system prompt line that works
Writing the language instruction in Portuguese itself is a strong signal:
Responda em português do Brasil, tratando o usuário por "você", de forma cordial e objetiva.(Answer in Brazilian Portuguese, addressing the user as você, cordially and objectively.)
Keep the rest of your instructions in whichever language your team maintains best; the model follows mixed-language system prompts reliably, and the reply language follows this line.
Test before launch
- Collect 30 or more real Portuguese messages, including short, misspelt and mixed-language ones.
- Have a fluent speaker grade replies for correctness, register and naturalness; then calibrate a rubric grader on their grades (Evaluate).
- Check rendering in your actual UI: line breaks, truncation and fonts.
- Re-run the set whenever you change the prompt or the model.