How Do You Refer to Decades in Spanish?

How do you refer to decades (such as the '70s) in Spanish?

The most common way to refer to "the '70s" would be los años 70 or los años setenta. Note that when the decade is written numerically, most writers do not precede it by an apostrophe as is usually done in English. (Doing so would usually be seen as an ill-advised imitation of English.) The 70 forms and the setenta form appear to be used about equally, although the spelled-out version is more common in formal writing. Note that the number of the decade is not made plural.

It is also fairly common to use a longer form, la década de los setenta, which again is somewhat formal. The longer form also would normally be used when the century isn't clear from the context, as in la década de 1870 or, less commonly, la década de los 1870. The form la década de los 1870s (note the s after the year) is very seldom used.

It is possible to use phrases such as los setentas or los cincuentas alone to refer to the '70s and '50s, but it is probably not best to use that form unless you hear it being used by native speakers. Again, these can be seen as anglicisms.

The word decenio is also used as a translation for "decade." Thus it is possible to say el decenio de los setenta or el decenio de 1970. Decenio is more formal or literary than década.