You must shoot the 100 yard and 200 yard to know as GB said.
I personally use the X2 method and I'm normaly not that far off, and it lowers expectations also.
Example my 3 or 5 shot groups at 100 yards is 3/4" center to center so I figure on a 1 1/2" group at 200 yards but like I said that doesn’t always work. Sometimes I only gain 1/4" group size but others I gain 2" so there isn’t any real science on it, other than to shoot it.
Warf