Portuguese writing rules for dates, days, and months

Introduction

This guide explains Portuguese writing rules for dates, days, and months with a focus on Brazilian Portuguese. You will learn how to write dates, say weekdays and months correctly in writing, choose prepositions and punctuation, and compose practical messages, emails, forms, and short notes. Examples and sample sentences are provided in Brazilian Portuguese for immediate use.

Basic date formats in Brazilian Portuguese

Brazil uses day-month-year order in most contexts, both formal and informal. Numbers are usually written with digits for day and year and either digits or words for the month name. There are small variations depending on formality, punctuation, and whether you use numerals or words.

Common numeric formats:

DD/MM/YYYY — 05/04/2026

DD-MM-YYYY — 05-04-2026

YYYY-MM-DD — 2026-04-05 (used in computing, official records sometimes prefer this ISO-like form)

When writing the month as a word, the pattern is: dia de mês de ano. Example:

5 de abril de 2026

Capitalization and months

In Brazilian Portuguese, month and weekday names are not capitalized unless they start a sentence or appear in a title. Use lowercase for abril, maio, segunda-feira, sábado.

Example sentence for a message:

Meu voo é em 5 de abril de 2026.

Writing months: names, spelling, and accents

Brazilian Portuguese month names are straightforward and mostly similar to English but with Portuguese spelling. There are no accents in month names. List of months for reference (use these in examples or forms):

janeiro

fevereiro

março

abril

maio

junho

julho

agosto

setembro

outubro

novembro

dezembro

Note that março contains a cedilla-like c with a cedilha in some words, but here it is spelled março with a cedilha on the c. Always write março with ç and the correct vowel accent if applicable.

Weekday names and spelling

Weekday names in Brazilian Portuguese follow a regular pattern and are not capitalized in normal sentences. The weekdays are:

segunda-feira

terça-feira

quarta-feira

quinta-feira

sexta-feira

sábado

domingo

Note the hyphen and the use of feira for Monday to Friday. Terça-feira and sexta-feira have accents on the first vowel. Use these words exactly in messages and schedule notes.

Prepositions and articles with dates

When writing dates in sentences, use de between day, month, and year: dia de mês de ano. The definite article o or a is optional before the day when you speak, but in writing you can omit it in short notes. For formal writing, you may see o dia 5 de abril de 2026 or simplesmente 5 de abril de 2026.

Examples:

Reunião marcada para 10 de maio de 2026.

O prazo termina em 31 de dezembro de 2026.

Using em and no/na

For saying on a weekday or date use em: em segunda-feira, em 5 de abril. For months you can also say no mês de abril by combining com o: no abril is incorrect. Correct forms:

Vou viajar em junho.

A loja fecha na terça-feira.

Important: use na before feminine weekdays or months if you include the article: na terça-feira, no sábado.

Abbreviations for months and weekdays

Common abbreviations in calendars and forms are three-letter or mixed forms. Use these in schedules, calendar inputs, or SMS when space is limited.

Months (abbreviations): jan, fev, mar, abr, mai, jun, jul, ago, set, out, nov, dez

Weekdays (abbreviations): seg, ter, qua, qui, sex, sáb, dom

When abbreviating sábado, include the accent in short forms like sáb. In casual digital messages, accents are sometimes dropped, but correct written form keeps the accent.

Ordinal dates and writing the day with adjectives

Ordinals are used to say first, second, third, etc., as in the first of the month. In Brazilian Portuguese, ordinals agree in gender with the noun dia (masculine). Ordinals are often used in formal writing and invitations.

Examples:

1º de janeiro de 2026 (primeiro de janeiro de 2026)

2º de fevereiro de 2026 (segundo de fevereiro de 2026)

Notice the masculine ordinal marker º after the numeral for dia: 1º, 2º, 3º. You may also write the full word primeiro when you want a more natural tone: primeiro de março de 2026.

Using articles with ordinals

In formal invitations and announcements, include the article: O evento será realizado no dia 1º de maio de 2026. In everyday messages you can omit o dia: Evento: 1º de maio de 2026.

Punctuation and separators

When writing dates inside sentences use commas only when the sentence requires them, not to separate day, month, and year. Use slashes or hyphens for compact numeric forms. When writing full dates in words do not use commas between parts.

Correct: Encontro em 15 de junho de 2026 às 14h.

Incorrect: Encontro em 15, de junho, de 2026.

Time and dates: In Brazil, hours are often written with h or : for digital formats. Examples:

14h — common in written schedules

14:00 — digital and formal timetables

Practical writing examples for everyday contexts

Here are realistic examples you can copy and adapt for messages, emails, forms, and notes.

Appointment confirmation (SMS): Olá, confirmado: consulta dia 12 de maio de 2026 às 10h.

Email to colleague: Podemos reagendar para segunda-feira, 8 de junho de 2026? Estou disponível das 9h às 11h.

Travel note for booking: Check-in em 05/04/2026. Check-out em 12/04/2026.

Form field example: Data de nascimento: 23/09/1995

Restaurant reservation: Reserva para sábado, 20 de novembro de 2026, às 20h, em nome de Ana.

Class exercise answer: Hoje é quarta-feira, 7 de abril de 2026.

Short messages and chat phrases

When writing quickly in chat or WhatsApp, Brazilians often write the day and month numerically and use abbreviations for weekdays.

Examples you might send:

Confirmado para 14/07/2026?

Encontro na seg às 15h?

Lembrete: reunião 03-08-2026, 09:00.

Common beginner mistakes and how to avoid them

Mistake: Using English month names or wrong order (month-day-year). Fix: Remember Brazilian order is day-month-year or use month name in Portuguese.

Incorrect: 04/05/2026 (ambiguous for learners from the US). Clarify: 4 de maio de 2026 or 04/05/2026 with an explanatory label.

Mistake: Capitalizing months or weekdays. Fix: Use lowercase: maio, terça-feira.

Mistake: Omitting de between day and month in full-word dates. Fix: Use 10 de julho, not 10 julho.

Mistake: Using the wrong preposition for days. Fix: Use em for days and months, na/no when combined with an article: em setembro, na terça-feira.

Exercises and practice prompts

Fill-in practice for forms: write your birth date using DD/MM/YYYY. Example answer: 15/03/1990

Write a short email to reschedule a meeting to a specific weekday and date. Example sentence: Podemos remarcar para quinta-feira, 18 de março de 2026?

Translate and write a travel note: My flight is on April 5 at 8:30. Example: Meu voo é em 5 de abril de 2026 às 8h30.

Tone and formality tips

For formal letters and official documents, use full words and ordinals: O prazo expira em 30 de abril de 2026. For informal messages, numeric forms and abbreviations are fine: Visto: 30/04/2026.

Use polite markers in emails with dates: Poderia confirmar sua disponibilidade para 22 de maio de 2026? This keeps the tone respectful.

Quick reference cheat-sheet

Date order: day-month-year — 05/04/2026 or 5 de abril de 2026

Months lowercase: janeiro, fevereiro, março, abril, maio, junho, julho, agosto, setembro, outubro, novembro, dezembro

Weekdays lowercase with hyphens: segunda-feira, terça-feira, quarta-feira, quinta-feira, sexta-feira, sábado, domingo

Prepositions: em (in/on), no/na when combined with article: na terça-feira, no mês de maio

Abbreviations: jan, fev, mar, abr, mai, jun, jul, ago, set, out, nov, dez; seg, ter, qua, qui, sex, sáb, dom

Conclusion

Writing dates, days, and months in Brazilian Portuguese is straightforward when you remember the day-month-year order, lowercase month and weekday names, use of de between date parts, and common abbreviations. Practice with the provided examples to build confidence for messages, emails, forms, and everyday notes.