In English there are two possible translations of ‘acostumbrar’ or ‘acostumbrarse’.
1) ‘to be used to + noun or -ing’ or ‘get used to + noun or -ing’
2) ‘to be accustomed to + noun or -ing’
‘to be used to’ is the most commonly used.
1. Estoy acostumbrado al calor.
The above sentence refers to a state NOT a change. Notice there is no reflexive pronoun ‘se’. There is also only a noun following the verb ‘calor’.
In this case we use: ‘to be used to + noun’
I am used to the heat. (with the article this mean, specific heat, like the heat in July.)
I am used to heat. (with no article this refers to heat in general.)
2. Me estoy acostumbrando al calor.
The above sentence refers to a change rather than a state. Notice there is a reflexive pronoun ‘se’ and the verb is in the gerund form ‘acostumbrando’.
In this case we use: ‘to be getting used to + noun’
I’m getting used to the heat.
3. Ella se acostumbra a las nuevas tecnologías en poco tiempo.
The above sentence refers to a change that generally happens, but is not necessarily happening now.
In this case we use: ‘get used to + noun’
She gets used to new technology very quickly.
4. Nosotros estamos acostumbrados a andar mucho.
The above sentence refers to a state NOT a change, like in the first example. However, we have an action ‘andar’ instead of a simple noun.
In this case we use: ‘to be used to + -ing’
We are used to walking a lot.
5. Nosotros nos estamos acostumbrando a andar dos horas por día.
The above sentence refers to a change. Therefore it is similar to example two above.
In this case we use ‘to be getting used to + verb’
We are getting used to walking two hours per day.
In order to change tenses we simply apply the change to either ‘be’ or ‘get’ as necessary.
Estaba acostumbrado al calor.
I was used to the heat.
Me acostumbré al calor.
I got used to the heat.
Me acostumbraré al calor
I’ll get used to the heat.
‘to be accustomed to’ is not used as often and is more formal.
We can simply apply the rules of ‘used to’ to ‘accustomed to’
The following sentence all mean the same thing. Keep in mind that ‘accustomed’ is less often used and more formal.
I’m used to noise.
I’m accustomed to noise.
John got used to taking the metro.
John got accustomed to taking the metro.
She’s getting used to London.
She’s getting accustomed to London.
She’ll get used to London.
She’ll get accustomed to London.