Is it correct to use "would" lie this?
Dear teachers

Could you please check this context:

He's 18. He now would be 20 perhaps. Since this report is from last year.

Edit: I meant 19, not 20. Sorry about that.

Question

Is it correct to use "would" lie this?
Dear teachers

Could you please check this context:

He's 18. He now would be 20 perhaps. Since this report is from last year.

Edit: I meant 19, not 20. Sorry about that.

Answer

"Would" suggests "I guess". We don't have the absolute facts, so we use a modal.  Perhaps in reality he's still 19. We don't know when his birthday is.

The first sentence needs to be "He was eighteen" ("he was" does not contract), or if you are looking at a photo, you can say "he's eighteen", ie. in the photo.

Answer

I'm slightly confused why in one year he's aged two, unless the report was based on information the year earlier in which case I would say:
 'He was 18, but would be nearer/approximately 20 now, as the report was written/produced/published last year'.

Answer

"would" is certainly wrong here if he's still alive.