Por muy pequeño que sea el piso, siempre cabe un perchero junto a la puerta.

It’s a very common Spanish pattern meaning no matter how small..., however small..., or even if it is very small.

The structure is:

por muy + adjective/adverb + que + subjunctive

So here:

• por muy pequeño que sea el piso = no matter how small the flat is

You can use the same pattern with other adjectives:

• Por muy caro que sea, lo compraré. = No matter how expensive it is, I’ll buy it.
• Por muy tarde que sea, te llamaré. = No matter how late it is, I’ll call you.

It’s a set expression, so it’s best learned as a chunk.

Because after por muy ... que, Spanish normally uses the subjunctive.

Here, sea is the present subjunctive of ser.

Why subjunctive? Because the sentence is not simply stating a fact about the flat; it’s expressing a kind of concession: regardless of how small it may be.

Compare:

• Es pequeño. = It is small.
• Por muy pequeño que sea... = However small it may be / No matter how small it is...

So sea is required by this grammar pattern.

Because pequeño agrees with el piso.

• piso is masculine singular
• so the adjective must also be masculine singular: pequeño

Examples:

• el piso pequeño
• la casa pequeña
• los pisos pequeños
• las casas pequeñas

In the sentence, the adjective comes before the noun in the structure por muy pequeño que sea el piso, but it still agrees with piso.

In Spain, piso usually means flat or apartment.

That can confuse English speakers because piso can also mean floor in other contexts. But here, because of the sentence, it clearly means flat/apartment.

In Spain:

• un piso = a flat/an apartment
• el primer piso = the first floor

So the word has more than one meaning, and context tells you which one is intended.

Cabe comes from the verb caber, which means to fit.

So:

• cabe un perchero = a coat stand fits

This verb is very common for talking about space:

• No cabe aquí. = It doesn’t fit here.
• ¿Cabe en el maletero? = Does it fit in the boot/trunk?
• Caben dos sillas más. = Two more chairs fit.

In your sentence, siempre cabe un perchero means that there is always enough space for a coat stand.

Both caber and entrar can sometimes be translated as to fit, but they are not exactly the same.

• caber focuses on whether there is enough space
• entrar often focuses more on going in / being able to get into a place

Here, cabe un perchero is the most natural choice because the idea is spatial capacity: there is room for a coat stand.

Compare:

• No cabe en la habitación. = It doesn’t fit in the room.
• No entra por la puerta. = It doesn’t go through the door.

So caber is especially appropriate in this sentence.

Because in Spanish, it is very normal for the subject to come after the verb, especially with verbs like caber, faltar, sobrar, gustar, and others where the sentence introduces what exists, fits, remains, etc.

So:

• Siempre cabe un perchero...

sounds natural and idiomatic.

You could understand it almost like:

• There is always room for a coat stand...

If you said Un perchero siempre cabe..., it would sound more marked or contrastive, as if you were specially emphasizing un perchero.

Perchero usually means a coat stand, coat rack, or hall stand, depending on the design.

It is not the same as percha:

• percha = hanger
• perchero = coat rack / coat stand

So in this sentence, it means a piece of furniture or wall fixture where you hang coats, typically near the entrance.

Junto a la puerta means next to the door or by the door.

It is very similar to al lado de la puerta. In many cases, they mean almost the same thing.

• junto a often sounds a little more compact or slightly more formal/written
• al lado de is very common and everyday

So:

• junto a la puerta
• al lado de la puerta

are both natural here.

Because Spanish only contracts:

• a + el = al
• de + el = del

There is no contraction with la.

So:

• junto a la puerta = correct
• junto al puerta = incorrect

If the noun were masculine, you would get a contraction:

• junto al armario = next to the wardrobe

Yes, that is possible, and the meaning is similar:

• Aunque el piso sea muy pequeño, siempre cabe un perchero junto a la puerta.

This means Although the flat may be very small, there’s always room for a coat stand by the door.

But por muy pequeño que sea has a slightly stronger no matter how small feeling. It emphasizes that the statement remains true at any degree of smallness.

So:

• aunque... = although / even if
• por muy ... que... = no matter how ...

Both are correct, but the original sentence is more idiomatic for this idea.

It would change to agree with the number of things that fit.

The verb is caber, and in the present tense:

• cabe = singular
• caben = plural

So:

• Siempre cabe un perchero. = A coat stand always fits.
• Siempre caben dos sillas. = Two chairs always fit.

This is useful because English learners sometimes treat it like an impersonal structure, but it is a normal verb agreeing with its subject.

Yes, mainly because of piso meaning flat/apartment, which is especially common in Spain.

The grammar itself is not specifically Spain-only:

• por muy ... que + subjunctive
• caber
• junto a

are all general Spanish.

But a speaker from Latin America might more naturally say apartamento or departamento depending on the country, instead of piso.