Estimate object distance, size or angular size using the small-angle relation, with milliradian and MOA results and converted length units.
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Milliradian Distance Formula
The following small-angle formula estimates distance. It assumes a known dimension perpendicular to the line of sight and mils defined as milliradians.
- Where Dm is the Milliradian Distance (yards)
- S is the size (in)
- mrad is the milliradians (mils)
For size in inches and distance in yards, multiply by 1000/36 (approximately 27.777778), then divide by the angular size in milliradians. The calculator uses this unrounded coefficient.
How to Calculate Milliradian Distance?
The following example problems outline how to calculate Milliradian Distance.
Example Problem #1:
- First, determine the size (in).
- The size (in) is given as 35.
- Next, determine the milliradians (mils).
- The milliradians (mils) is provided as 4.5.
- Finally, calculate the Milliradian Distance using the equation above:
Dm ≈ S * (1000/36) / mrad
The values given above are inserted into the equation below and the solution is calculated:
Dm ≈ 35 * (1000/36) / 4.5 = 216.05 yards
Example Problem #2:
For this problem, the variables needed are provided below:
size (in) = 70
milliradians (mils) = 6.7
This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer.
Dm ≈ S * (1000/36) / mrad = ?
