How accurate is Portuguese speech to text with local Whisper?
Portuguese is one of Whisper's strongest languages. On the Whisper paper's benchmarks the large model lands around 5-7% word error rate on Portuguese - in the top tier with Spanish, French, and German. Everyday dictation runs a little higher than a clean benchmark, but Portuguese is production-grade on a good local model.
The important nuance is variant. Whisper was trained on far more Brazilian Portuguese than European Portuguese - Brazil has around 211 million speakers to Portugal's 10 million - so Brazilian PT transcribes around 5% word error rate while European PT lands nearer 7-9%, largely because of European Portuguese's heavy unstressed-vowel reduction. Both are usable; Brazilian is simply the better-trained case.
Accuracy tracks model size as with every language. Medium is the practical floor for Portuguese; large and large-v3 are where it reaches production quality. SnailText's free tier covers the compact models, with the larger Portuguese-quality models on Pro.
Brazilian and European Portuguese, and the 1990 agreement
Brazilian vs European Portuguese is the defining Portuguese challenge. They differ in accent, vocabulary, and some spelling, and Whisper leans Brazilian. SnailText's Portuguese prompt biases spelling and punctuation toward a neutral standard so European Portuguese users are not fighting Brazilian defaults on every line.
The 1990 Orthographic Agreement standardized - but did not merge - the two spelling systems, dropping silent consonants and some accents toward roughly 98% convergence. SnailText keeps its spelling neutral to that agreement, so the output is correct for readers on both sides of the Atlantic rather than committing to one older regional norm.
Nasal vowels and diacritics (ã õ, á â ç) are where accent and local terminology can slip. The model handles most of them; the Portuguese cleanup pass keeps the output consistent.
Why local, and why Portuguese-tuned
Most dictation tools ship stock Whisper and inherit its Brazilian bias and its variant quirks unchanged. SnailText is the combination that addresses them privately: the same best-in-class local Whisper model, plus a Portuguese-tuned prompt and a Portuguese-aware cleanup pass with 1990-agreement-neutral spelling, running entirely on your own hardware.
Brazil is a huge, underserved dictation market - the sixth most-spoken native language in the world, and around 80% of all Portuguese speakers. Whether you are in São Paulo or Lisbon, the audio is processed in RAM and never uploaded, so the privacy guarantee is architectural, and it works with no internet.
Prefer the interface in Portuguese? SnailText ships a fully Portuguese UI. The dictation engine is the same; these pages are about dictating in Portuguese whatever your interface language.