Is "weightage" an English word?

Is weightage an English word?

We use it a lot in India, but I couldn't find it in my Oxford Dictionary.

I was able to find it in the Collins English Dictionary, which marks it as Indian:

weightage chiefly (Indian) another name for weighting

The British National Corpus has 259 cites for weighting, but not a single one for weightage.

Cambridge Dictionary has included the word 'weightage' and mentioned it as 'Indian English' origin. The meaning given is:

(noun) the value or importance of something when compared with another thing.
The entrance test carries 40 percent weightage in the final result.

Weightage is not a word used in American or British English. For the example you give, AmEng academics use the verb to be weighted.

The entrance test is weighted 30% of your final grade.