Fractions and decimals are where Brazilian Portuguese borrows two systems you already half-know — cardinals for the top of a fraction, ordinals for the bottom — and then layers on two genuine surprises for English speakers: the suffix -avos for large denominators, and the fact that decimals are written and read with a comma (vírgula), the mirror image of the English point. This page assumes you're comfortable with cardinal numbers and ordinals.
How fractions are built
A fraction has a numerator (top) and a denominator (bottom). In Portuguese:
- The numerator is a plain cardinal: um, dois, três.
- The denominator is an ordinal — terço, quarto, quinto — for denominators 2 through 10.
The numerator also pluralizes the denominator: um terço (one third) but dois terços (two thirds).
| Fraction | Portuguese |
|---|---|
| 1/2 | um meio / a metade |
| 1/3 | um terço |
| 2/3 | dois terços |
| 1/4 | um quarto |
| 3/4 | três quartos |
| 1/5 | um quinto |
| 2/5 | dois quintos |
| 1/10 | um décimo |
Note that the denominator for 1/3 is terço, a special fraction word, not the ordinal terceiro. From 1/4 onward, the denominator is the regular ordinal: quarto, quinto, sexto, sétimo, oitavo, nono, décimo.
Já li dois terços do livro e não consigo parar.
I've already read two thirds of the book and I can't stop.
Só sobrou um quarto do bolo depois da festa.
Only a quarter of the cake was left after the party.
Denominators above ten: the -avos suffix
When the denominator is larger than 10, Portuguese stops using ordinals (nobody wants to say um décimo segundo for 1/12). Instead it takes the cardinal number plus the suffix -avos:
- 1/11 = um onze avos
- 1/12 = um doze avos
- 3/12 = três doze avos
- 1/20 = um vinte avos
- 7/100 = sete cem avos (or, formally, sete centésimos)
Esse parafuso é de cinco dezesseis avos de polegada.
This screw is five-sixteenths of an inch.
A receita pede três quartos de xícara de açúcar.
The recipe calls for three quarters of a cup of sugar.
Meio, meia, and metade — three words for "half"
English has one word, half. Portuguese splits the concept:
meio / meia is an adjective meaning "half a..." It agrees in gender with the noun it modifies, and comes before it:
- meio litro — half a liter (litro is masculine)
- meia hora — half an hour (hora is feminine)
- meio quilo — half a kilo
- meia dúzia — half a dozen
Me dá meio quilo de tomate, por favor.
Give me half a kilo of tomatoes, please.
A reunião dura só meia hora.
The meeting only lasts half an hour.
metade is a noun meaning "the half" — a concrete portion. It's preceded by an article and usually followed by de:
- a metade do bolo — half (of) the cake
- a metade da turma — half the class
Comi a metade da pizza sozinho, confesso.
I ate half the pizza by myself, I admit.
The distinction mirrors English "half a cake" (meio bolo, the adjective) versus "the half of the cake" (a metade do bolo, the noun). When half introduces the quantity, use meio/meia; when it names a portion you can point to, use metade.
Metade dos convidados não apareceu.
Half the guests didn't show up.
Decimals: the comma is the point
This is the most important practical point on the page. Brazil uses a comma as the decimal separator, and reads it aloud as vírgula ("comma"). Where English says "three point five" and writes 3.5, Brazilian Portuguese says três vírgula cinco and writes 3,5.
| Written (BR) | Read aloud | English equivalent |
|---|---|---|
| 3,5 | três vírgula cinco | 3.5 (three point five) |
| 0,75 | zero vírgula setenta e cinco | 0.75 |
| 2,99 | dois vírgula noventa e nove | 2.99 |
| 10,5 | dez vírgula cinco | 10.5 |
A gasolina está custando seis vírgula quarenta e nove o litro.
Gas is costing six point four nine a liter.
A nota dele foi sete vírgula cinco na prova.
His grade on the test was seven point five.
The digits after the comma can be read individually or as a whole number; both are heard. For prices, Brazilians often skip vírgula entirely and read it like money: R$ 6,49 becomes seis e quarenta e nove ("six and forty-nine," i.e. six reais and forty-nine centavos). But for a pure decimal — a measurement, a grade, a statistic — vírgula is the standard reading.
O paciente está com trinta e oito vírgula dois de febre.
The patient has a fever of thirty-eight point two.
Remember the companion rule from large cardinals: the period marks thousands. So 1.234,56 is "one thousand two hundred thirty-four point fifty-six." Everything is the reverse of English.
Common Mistakes
❌ O preço é três ponto cinco.
Incorrect — Portuguese reads the decimal separator as 'vírgula', not 'ponto'.
✅ O preço é três vírgula cinco.
The price is three point five.
This is the single most common decimal error from English speakers — saying ponto (point) instead of vírgula.
❌ Espera meio hora, já volto.
Incorrect — 'hora' is feminine, so 'half' must agree: 'meia hora'.
✅ Espera meia hora, já volto.
Wait half an hour, I'll be right back.
❌ Comi meia do bolo.
Incorrect — 'the half' (a portion) is the noun 'metade'.
✅ Comi a metade do bolo.
I ate half the cake.
❌ Essa peça mede um décimo segundo de polegada.
Incorrect — denominators above 10 use '-avos', not ordinals.
✅ Essa peça mede um doze avos de polegada.
This part measures one-twelfth of an inch.
❌ Custa R$ 1,250.
Incorrect — a comma marks decimals; a thousand uses a period.
✅ Custa R$ 1.250.
It costs R$ 1,250.
Key Takeaways
- Fractions = cardinal numerator + ordinal denominator (dois terços) for 2–10; above 10 use cardinal + -avos (um doze avos).
- meio/meia = "half a" (adjective, agrees: meia hora); metade = "the half" (noun: a metade do bolo).
- Decimals use a comma, read aloud as vírgula (três vírgula cinco = 3,5) — the exact reverse of the English point.
- The period marks thousands, so 1.250,75 is one thousand two hundred fifty point seventy-five.
Now practice Portuguese
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Start learning Portuguese→Related Topics
- Percentages and Math OperationsA2 — How Brazilian Portuguese reads percentages with 'por cento', the four arithmetic operations, multiples like dobro/triplo/metade, and the phone-number 'meia'.
- Numbers: OverviewA1 — A map of Brazilian Portuguese numbers — gender agreement on um/uma, dois/duas and the hundreds, the reversed comma-decimal/period-thousands punctuation, and the 'e' that links the parts.
- Ordinal Numbers (First, Second, Third)A2 — Brazilian Portuguese ordinals from primeiro to milésimo: how they agree in gender and number, how they abbreviate, and why Brazilians switch to cardinals above tenth.
- Numerals as DeterminersA1 — Numbers used to determine nouns — why most cardinals are invariable but 'um/uma', 'dois/duas' (and the hundreds) agree in gender, how ordinals sit before the noun, and the gender of 'meio/meia'.