The MilDot Reticle
put, the Mil-Dot is a range estimating reticle that was developed
for military applications. The space between the dot centers
subtends one milliradian (Mil). One Mil subtends 3.6" at 100 yards,
or 36" at 1,000 yards.
This reticle was developed in the late 1970s to help U.S. Marine
snipers estimate distances, and is now standard for all military
branches. The space between dot centers subtends one milliradian
(mil) hence the name mil-dot. Contrary to popular belief it does
not stand for "military dot". One mil subtends 3.6 inches at 100
yards or 36 inches at 1,000 yards. To use this system effectively
you must know the size of the target. For instance most people are
an average of 6 feet tall or 2 yards. The formula used for
determining range to the target is (size of target x 1000 divided
by number of mils the target covers).
Height of target (yards) X 1,000 = Range (yards)/
Height of target (mils)
You can do these calculations with a calculator or use a
reference table like the ones listed below. But remember that your
answer is only as accurate as the numbers you plug into the
formula. An error of just a 1/4 mil will cause an error in target
range. Also an error in estimating the size of your target will
cause an error in target range.
The top line on the table represents the size of the target as
measured in feet or inches. The second line represents the
conversion of the foot measurements to yards. The left column shows
the mil measurements to the nearest 1/2 mil. The mil scale can be
split to the nearest 1/8 mil for a more accurate range measurement.
To use the table follow the instructions below.
- Estimate height of target and locate across the top.
- Measure height of target in mils and locate down the side.
- Move down from the top and right from the side to find the
range in yards.
Range Estimating with the Mil-Dot Reticle
Dots are spaced in one mil (milliradian) increments on the
crosshair. Using the mil formula, a table can be created like the
ones above that is based on the size of the object being targeted.
Just look through the scope, bracket the object between dots, and
refer to the table for an estimated distance to target.
The radian is a unit-less measure which is equivalent in use to
degrees. It tells you how far around a circle you have gone. 2 PI
radians = 360 degrees. Using 3.14 as the value of PI, 6.28 radians
take you all the way around a circle. Using a Cartesian coordinate
system, you can use "x"- and "y"-values to define any point on the
plane. Radians are used in a coordinate system called "polar
coordinates." A point on the plane is defined, in the polar
coordinate system, using the radian and the radius. The radian
defines the amount of rotation and the radius gives the distance
from the origin (in a negative or positive direction).
The radian is another measurement of rotation (the
degree/minute/second-system being the first). This is the system
used in the mil-dot reticle. We use the same equation that we used
before, but, instead of your calculator being in "degree" mode,
switch it to "radian" mode. One milliradian = 1/1000 (.001)
radians. So, type .001 into your calculator and hit the "tangent"
button. Then multiply this by "distance to the target." Finally,
multiply this by 36 to get inches subtended at the given distance.
With the calculator in "radian" mode, type:
tangent(.001)*100*36 = 3.6000012
So one milliradian is just over 3.6 inches at 100 yards. If we
extrapolate, two milliradian equal about 6 feet at one-thousand
The mil-dot reticle was designed around the measurement unit of
the milliradian. The dots themselves were designed with this in
mind and the spacing of the dots was also based upon the
milliradian. This allows the shooter to calculate the distance to
an object of known height or width. Height of the target in yards
divided by the height of the target in milliradians multiplied by
1000 equals the distance to the target in yards. For example, take
a 6-foot-tall man (2 yards). Let's say that the top of his head
lines up with one dot and his feet line up four dots down. So:
(2/4)*1000 = 500 yards away. This same technique can be used to
estimate lead on a moving target or to compensate for deflection on
a windy day.
The distance from the center of one dot to the center of the
next dot is 1 milliradian. We are told (by Leupold) that the length
of a dot on one of their reticles is 1/4 milliradian (Given this
much information, one can determine that the distance between dots
is 3/4 milliradian.).* I use the term "length" because the mil-dot
is not round in all cases. It is oblong in some scopes and round in
others (Tasco). The width of each dot is an arbitrary distance and
is not used for any practical purpose. Like a duplex reticle, the
mil-dot reticle is thicker toward the edges and uses thin lines in
the middle where the dots are located and the crosshairs cross. The
distance between the opposite thick portions is 10 milliradian on
*NOTE: 1/4 milliradian = .9" and 3/4 MOA =
.785", so, obviously, a mil-dot cannot be both 1/4 milliradian and
3/4 MOA. The maker of the mil-dot reticles for Leupold explains:
the dots on their mil-dot reticles are 1/4 mil. They are not 3/4
MOA. Apparently, Leupold just figured that more shooters understand
MOA than milliradian, so they just gave a figure (in MOA) that was
close, but not super precise.
To use a mil-dot reticle effectively, all one need remember is
that the distance between dot centers is 36" at 1000 yards. This
lets you determine the range of a target of known size. At that
point, you can dial the scope in for proper elevation OR use the
dots to hold over the proper amount. The dots on the horizontal
crosshair can be used to lead a target (if you know the range to
the target, then you'll know the distance between dots, and thus
the distance to lead) or to compensate for deflection.
If you own a mil-dot scope or are going to in the future you
need to check out this new product called The
Mil Dot Master.
The term "minute-of-angle" (MOA) is used regularly by target
shooters at the range, but is probably understood thoroughly by few
(the same goes for mil-dots). Defined loosely, one MOA = 1" @ 100
yards; so, if you shot your rifle 5 times into a 100-yard target
and every shot went into a one-inch circle you had drawn on the
paper, then your rifle could be said to shoot 1 MOA. Likewise, if
every shot goes into a two-inch circle at 200 yards, then you're
shooting 1 MOA. A 10-inch group at 500 yards would be 2 MOA.
Now for the fun part. There are 360 degrees in a circle. Each
degree can be broken down further into minutes. There are 60
minutes in a degree. Likewise, there are 60 seconds in a minute.
Now, to figure out the distance subtended by 1 minute at any
particular distance, we need merely to plug those two values into a
simple trigonometric equation. The tangent function fits the bill
nicely. Here's the equation:
tan(angle) = distance subtended/distance to the
(units must be consistent--e.g., 1/36 of a yard [1"] divided by
Now, we know the angle (1 minute or 1/60 of a degree) and we
know the distance to the target (100 yards), but we need to figure
out the actual distance subtended at the target (i.e., is 1 MOA
actually 1" @ 100 yards?). What we need to do is solve for
"distance subtended." Here's our final equation:
tan(angle)*distance to the target = distance
Make sure your calculator is in "degree" mode (as opposed to
"radian" or "gradian") and type in 1/60 (for degrees) and hit the
"tangent" button. Then multiply that by 100 yards. This should give
you the distance (in yards) subtended at 100 yards. Multiply this
by 36 to get inches. The answer should be:
This is just a hair over the commonly quoted "one inch." At 1000
yards, this would be almost 10 1/2 inches. Apparently, it is just a
coincidence that 1 MOA happens to be REALLY close to 1" @ 100
yards. It is, however, quite convenient.