If a mil-dot covers 3.53 inches at 100 yards what is it 200,300,400 and so on?? It is my understanding that 3.53 at 100 yards is standard for most scopes.please help  [0j][uzi]

Well, I am going to suppose something here and probably be proven a total numbskull.  But, here goes...

If it covers 3.5 inches at 100 yds then I would call it a 3.5 MOA dot.  SO, at 200 yds it would cover 7 inches, 250 would cover 8.75, 300 would cover 10.5, and so on.  Can anyone confirm that I am an idiot? [:E]

Buy a Mildot Master from SWFA. It makes range estimation much easier.

You are close enough for government work when it comes to mils, but that is not exactly what they are. To quote the FM 6-40 (MCWP 3-1.6.19) Field Artillery Manual Gunnery, A mil is "a unit of measure for angles that is base on the angle subtended by 1/6400 of the circumference of a circle." For a historical context the mil was used by fortress (or foot) artillerymen prior to the First World War. The precision of the angle was necessary for the them to be able to attack fixed targets with indirect fire. This is opposed to the DC system used by the horse artillerymen of the day that used an angle 1/6000 of circle, this system is still used by former Soviet block nations. Because of the static nature of that war, the fortress artillerymen, eventual become the predominate arm and their mil system is adopted by the majority of the western European artillerymen as the standard, consequently the rest of military. The reason the historical look at why mil was that the mil-dot sight was developed by some Marine artillery officer that were on B-billets to the Weapons training Battalion, Quantico, Virginia, As artillery officers knew that artillerymen had been using mils for years to "turn" angles in order to determine distances. Turned angles were an extremely accurate method of determining distances when laying howitzers. And taking these very principles, they could use the mils in a direct fire sight used by snipers in order to determine range and apply hold over and lead. The basis of turning an angle is simple subtense using the mil relation formula. Again the FM 6-40 " a gunnery formula expressed as mils=W/R
in which mils is the angle of measurement in mils between two points, W is the lateral distance (width) in meters between two points, and R is the mean distance in thousands of meters to the points. This relation is approximately true for angular measurements less than 600 mils." This is often also seen in the common formula of W=(r/1000) x M. This is an approximation because of the fact that you are attempting to determine a cord between two points on the inside of angular measurements. In order to increase accuracy artillery FDC will multiply of divide by 1.0186 to convert the outside angular measurement to the true strait line distance. For a subtended angle you divide by 1.0186. You will find this yields 1 mil equaling 3.54 inches at 100 yards. Very close to the often cited 36 inches at 1000 yards.