Long range highpower rifle competitors have been using a simple formula for about 90 years at ranges from 600 to 1000 yards. It goes like this: range (in hundreds of yards) times wind speed (in mph) divided by 10 equals minutes of angle correction for a full value wind.
A full value of wind is one from either 3- or 9-o'clock relative to the line of fire. Half-value winds were from 1, 2, 4, 5, 7, 8, 10 and 11-o'clock. And a no-value wind was from "supper time" (6-o'clock) or midnight (12-o'clock). This method worked pretty good firing the old M2 173-grain boattail machine gun bullet from .30-06 Springfield M1903 and M1 Garand rifles. It at least got one on the 6-foot square target paper when winds were pretty strong.
With more recent cartridges shooting bullets that buck the wind a lot better, I've came up with a bit more realistic formula using the same type of simple math. And winds from 1, 5, 7 and 11 are really true half value ones (the sine of 30 degrees is 0.5). Winds from 2, 4, 8 and 10 are really closer to 90% ones (the sine of 60 degrees is 0.87).
1. Use a very good software program for ballistics such as that sold by Sierra Bullets to calcuate the wind drift for your bullets for each hundred yards of range you'll shoot at.
2. For each hundred yards of range, convert the bullet's drift in inches for a 9-o'clock 10 mph wind to minutes of angle (MOA).
3. Multiply each hundred yards of range times 10, then divide that number by the drift in MOA number for that range. The answer is your "magic number" for wind corrections at that range. Note the longer ranges will have smaller magic numbers than shorter ranges.
In use, you'll need something to measure wind speed. There's many types available from the simple Dwyer Gage to fancy, expensive digital electronic windmills. Then laser or estimate the range. Multiply the range in hundreds by the wind speed in mph then divide that answer by your magic number for that range.
Example: range is 600, six times indicated wind speed of 4 mph is 24 and dividing 24 by your magic number of 16 (Sierra 30 cal. 180-gr. SBT @ 3000 fps at 3000 ft elevation) equals a 1.5 MOA correction for a full-value 4 mph wind. If the wind's from 4-o'clock, 90% of 1.5 MOA is about 1.25 MOA, so make a 5 quarter-minute click correction to the right, aim, hold very still then take your shot.
I've used magic numbers for .264 Win. Mag, .308 Win., .30-.338 Win. Mag with much success. It's nice to read my old Dwyer wind gage, do the mental math for a .308 Win. shooting 155-gr. bullets out at 3050 fps at 6000 ft. elevation in a 20 mph crosswind then make the correction on a receiver sight that has 1/5th moa clicks fire the first shot at the 1000 yard target and miss the letter "X" in the center of the 10-inch diameter scoring ring by about half an inch. But then there's been times when I missed it by a couple of feet 'cause the downrange cross winds weren't the same speed as the wind at the firing point.