Binoculars Range Calculator

Created by Dominik Czernia, PhD candidate
Last updated: May 28, 2020

Our binoculars range calculator can be used with every binoculars that have a reticle superimposed upon the view. With this scale, you can estimate the distance to an object the height of which you know. In the following text, we have explained how you can gain such useful knowledge. Read on if you want to learn more about binoculars definition and principles.

Do you see a distant object over the horizon with your binoculars? With our Earth curvature calculator, you can find the height of an object that is partially hidden behind the horizon.

Binoculars definition

Binoculars consist of two telescopes which are mounted side-by-side and aligned in the same direction. Because the observer uses two eyes, the binoculars give him the opportunity to see a three-dimensional image (with a depth of view). The first binoculars were invented in the 17th century, and they used the optics of Galileo, i.e., two lenses: convex objective and a concave eyepiece lens. Check our thin lens equation calculator or lens maker calculator to learn more about the role of the lenses in optics.

Binoculars distance

In the military, angles are measured in milliradians - a thousandth of a radian (0.001 radians, often called a mil or mrad). In particular, a milliradian is the angle at which one meter can be seen from a distance of one kilometer. It can be expressed with below binoculars distance formula:

d = h * 1000 / Mil


  • d is the distance to the object,
  • h is the object height,
  • Mil is the angular height of the object expressed in mrad.

You can use the reticle (look at image below) in your binoculars to estimate the distance to the observed object. For example, if the height of the house h = 6m seen by the binoculars is Mil = 1 mrad, it means that the house is d = 6000 m away from you. All you need is to know the height of the object.

The picture of a reticle with vertical and horizontal scales

Distance measurements

In the field, it is sometimes useful to know the distance to locate a place of stay on the map or to plan the time of further passage. At the same time, it is one of those parameters that are difficult to measure accurately without instruments. You can estimate distance in different ways, i.e.:

  • step counting - you can convert the distance into meters or kilometers if you know the length of your step,
  • travel time - this is probably the most natural way to determine the distance. It doesn't matter how far it is to the river - the important thing is that we'll be there in 10 minutes.
  • binoculars - we have explained how to do it with this binoculars range calculator.
Dominik Czernia, PhD candidate
Object height
Angular height of the object
Distance to the object
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