Less formal is 4/ X is about 1cm; but in both cases you would need to indicate the measure is refers to;
For instance
X is about / approximately 1cm wide / long / high / deep / thick
Alternatively I believe you can also say;
X is about /approximately 1cm in width / length / height / depth / thickness
You could only say approximate in this context; referring to the phrases used:
X has an approximate width of 1cm
In Spanish would that literally be translate to...?
Aproximad@ = aproximate
"Tiene una anchura aproximada de 1 cm"
Aproximadamente = approximately
"Mide (es) aproximadamente 1 cm de ancho"
1. Approximate is an adjective (to describe a noun) and can be used as so:
My calculationsare approximate
We talked about an approximate period
Not "We talked about an approximately period"
2. Approximately is an adverb (accompanying a verb) and can be used in phrases such as:
Synonyms: around/about/in the region of/roughly
"When did you finish university?"
(I finished university) "Approximately ten years ago"
It will cost you approximately...
It is approximately ... high
3. Also as an intransive o transive verb
His description approximates to the facts
To approximate to (something/someone)
Thank you.