The preposition em (in, on, at) behaves like de in one key respect: it contracts with a long list of following words, and many of those contractions are obligatory in writing. Unlike de, the contractions of em with indefinite articles are also obligatory — you cannot write em um in standard European Portuguese, only num. This makes em the strictest of the four main Portuguese prepositions (de, em, a, por) when it comes to its merger rules.
This page catalogs every contraction of em with examples.
At a glance
| em + | Contracted form | Status |
|---|---|---|
| definite articles (o, a, os, as) | no, na, nos, nas | obligatory |
| indefinite articles (um, uma, uns, umas) | num, numa, nuns, numas | obligatory in writing |
| este/esse/aquele series | neste, nesse, naquele, etc. | obligatory |
| isto/isso/aquilo | nisto, nisso, naquilo | obligatory |
| ele/ela/eles/elas | nele, nela, neles, nelas | obligatory |
| outro/outra/outros/outras | noutro, noutra, noutros, noutras | optional |
| algum/alguma/alguns/algumas | nalgum, nalguma, nalguns, nalgumas | optional |
| onde | no contraction — em + onde is unusual | — |
em + definite articles (obligatory)
These are the core contractions of em with the four definite articles. They are required in every context — spoken, written, formal, or informal.
| o (m.sg.) | a (f.sg.) | os (m.pl.) | as (f.pl.) | |
|---|---|---|---|---|
| em | no | na | nos | nas |
As chaves estão na gaveta, ao lado do telemóvel.
The keys are in the drawer, next to the phone.
Vivemos no Porto há três anos.
We've been living in Porto for three years.
Os miúdos estão nos parques todos os sábados.
The kids are at the parks every Saturday.
Encontrei-a nas escadas do prédio.
I ran into her on the stairs of the building.
Notice how any common noun preceded by an article — a mesa, o jardim, os livros — triggers the contraction as soon as em joins them. Because Portuguese uses articles so heavily (with proper names, common nouns, and many abstract nouns), these four contractions appear in almost every sentence.
em + indefinite articles (obligatory)
Here is where em is stricter than de. The contractions with the indefinite articles um, uma, uns, umas are obligatory in modern written Portuguese. You should write num café, never em um café.
| um | uma | uns | umas | |
|---|---|---|---|---|
| em | num | numa | nuns | numas |
Vivo num apartamento pequeno no centro.
I live in a small apartment downtown.
Ontem jantei numa tasca maravilhosa em Alfama.
Yesterday I had dinner at a wonderful tavern in Alfama.
Os documentos estão guardados nuns ficheiros na arrecadação.
The documents are stored in some files in the storage room.
Encontrei-as numas caixas no sótão.
I found them in some boxes in the attic.
Compare this with de, where dum and de um coexist. For em, there is no such flexibility — the uncontracted form feels wrong in edited writing, even though you may hear it in very casual speech and dialectal variants.
em + demonstratives (obligatory)
The demonstrative family (este, esse, aquele) and the neuter demonstrative pronouns (isto, isso, aquilo) all contract obligatorily with em. These contractions start with n- and preserve the demonstrative's form.
| este/a series | esse/a series | aquele/a series | |
|---|---|---|---|
| m.sg. | neste | nesse | naquele |
| f.sg. | nesta | nessa | naquela |
| m.pl. | nestes | nesses | naqueles |
| f.pl. | nestas | nessas | naquelas |
| neuter | nisto | nisso | naquilo |
Neste bairro já vivem três gerações da minha família.
Three generations of my family have lived in this neighborhood.
Nessa loja vende-se queijo da Serra da Estrela.
That shop sells cheese from Serra da Estrela.
Naquele verão, estivemos todos juntos pela última vez.
That summer, we were all together for the last time.
Nunca tinha pensado nisto antes.
I'd never thought about this before.
Não vale a pena insistirmos nisso.
It's not worth us insisting on that.
Naquilo eu concordo contigo plenamente.
On that I completely agree with you.
The neuter pronouns nisto, nisso, naquilo are particularly common after verbs like pensar (to think), acreditar (to believe), concordar (to agree), insistir (to insist), all of which take em as their obligatory preposition.
em + personal pronouns (obligatory)
Em contracts with the third-person pronouns ele, ela, eles, elas. The merged forms show up mainly with verbs of mental attitude (pensar em, acreditar em, confiar em).
| ele | ela | eles | elas | |
|---|---|---|---|---|
| em | nele | nela | neles | nelas |
Confio nele para resolver o problema.
I trust him to solve the problem.
Penso nela todos os dias.
I think about her every day.
Nunca acreditei neles.
I've never believed in them.
Nunca mais pensei nelas depois daquela conversa.
I never thought about them again after that conversation.
As with de, the preposition em does not contract with eu, tu, nós, vós, or você. Pronouns change form after a preposition (eu → mim, tu → ti), but the preposition stays separate:
Ela pensa muito em mim.
She thinks about me a lot.
Confio plenamente em ti.
I trust you completely.
em + outro (optional)
Like de, em can contract with outro, outra, outros, outras, but the uncontracted form remains acceptable.
| outro | outra | outros | outras | |
|---|---|---|---|---|
| em | noutro / em outro | noutra / em outra | noutros / em outros | noutras / em outras |
Noutro dia falamos sobre isso com calma.
Some other day we'll talk about that calmly.
Prefiro ficar noutra parte do hotel.
I'd rather stay in a different part of the hotel.
Em outras circunstâncias, teria ajudado.
In other circumstances, I would have helped.
The contracted form noutro is perhaps slightly more common in everyday writing than dum is among de-contractions, but both are fully current.
em + algum (optional)
The indefinite algum also contracts optionally with em.
| algum | alguma | alguns | algumas | |
|---|---|---|---|---|
| em | nalgum / em algum | nalguma / em alguma | nalguns / em alguns | nalgumas / em algumas |
Nalguma parte daquele livro há uma citação famosa.
Somewhere in that book there's a famous quote.
Em algumas cidades o trânsito é insuportável.
In some cities the traffic is unbearable.
Both forms circulate freely. Nalguma is perhaps slightly more literary; em alguma is entirely neutral.
em + onde: no contraction
Unlike de, which contracts with onde into donde, the preposition em does not contract with onde. In fact, em before onde is unusual in modern Portuguese, because the location question already implies the preposition.
Onde estás?
Where are you?
Onde é que ele trabalha?
Where does he work?
You almost never hear em onde estás? — that phrasing sounds redundant. Portuguese onde means where in the locative sense already, so adding em is unnecessary.
The one context where you might see em onde is highly formal or emphatically contrastive writing, where the writer wants to stress the in where nuance:
Ela sabe em que bairro ele mora, mas não em qual rua.
She knows what neighborhood he lives in, but not which street. (em que, not em onde)
In practice, em que is used where English might demand in which, while onde alone covers most where questions.
Fixed expressions and quirks
Two patterns are worth noting:
neste / nesse / naquele followed by time units
Combined with nouns like dia, momento, instante, verão, these demonstratives form time phrases equivalent to on that day, at that moment, that summer:
Naquele dia, tudo mudou.
On that day, everything changed.
Neste momento não posso falar, liga-me mais tarde.
I can't talk right now, call me later.
Nisto / nisso meaning "on this point"
In discussions and arguments, nisto and nisso are shorthand for on this point / on that point:
Nisso concordo contigo.
On that I agree with you.
Nisto ele tem razão, não se pode negar.
On this, he's right, there's no denying it.
Putting it together
Real Portuguese chains em-contractions the same way it chains de-contractions. Paragraphs layer them without effort:
No sábado de manhã encontrámo-nos no café nos Restauradores.
On Saturday morning we met at the café at Restauradores.
Naquela altura vivíamos num prédio pequeno num bairro tranquilo.
Back then we lived in a small building in a quiet neighborhood.
Penso muito nisso, mas nunca cheguei a uma conclusão.
I think about that a lot, but I've never reached a conclusion.
Common mistakes
❌ Vivo em um apartamento pequeno.
Incorrect in written PT — em + um must contract to num.
✅ Vivo num apartamento pequeno.
I live in a small apartment.
❌ Penso muito em este assunto.
Incorrect — em + este must contract to neste.
✅ Penso muito neste assunto.
I think a lot about this matter.
❌ Confio em ele completamente.
Incorrect — em + ele must contract to nele.
✅ Confio nele completamente.
I trust him completely.
❌ Não quero pensar em isso agora.
Incorrect — em + isso must contract to nisso.
✅ Não quero pensar nisso agora.
I don't want to think about that right now.
❌ Em onde é que ela mora?
Unusual — onde alone suffices for location questions.
✅ Onde é que ela mora?
Where does she live?
Key takeaways
- Contractions of em with definite articles (no, na, nos, nas), indefinite articles (num, numa, nuns, numas), demonstratives (neste, nesse, naquele), neuter pronouns (nisto, nisso, naquilo), and personal pronouns (nele, nela, neles, nelas) are all obligatory in writing.
- Unlike de, the contractions of em with um/uma are not optional — write num, not em um.
- Contractions of em with outro and algum are optional — both noutro and em outro are current.
- Em does not contract with onde. Use plain onde for location questions.
- Em does not contract with mim, ti, nós, vós, or você.
For the parallel system with de, see contractions with de. For the preposition a and the grave-accented forms, see contractions with a.
Related Topics
- Portuguese Prepositions OverviewA1 — Introduction to Portuguese prepositions and their uses, including the obligatory contractions that set European Portuguese apart.
- The Preposition emA1 — Uses of the preposition em — static location, time, and state — and why Portuguese uses de (not em) for transport.
- Contractions with deA1 — How the preposition de contracts with articles, demonstratives, pronouns, and other words — a complete reference.
- Contractions with a (the grave accent)A2 — How the preposition a contracts with articles and distal demonstratives — ao, à, aos, às, àquele — and why the grave accent matters.