How to Estimate Distances (by Using Your Thumb and Eyes)

Step-by-Step Guide

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   Step 1: Place yourself at a good vantage point.

   To estimate distance, you need a clear line of sight.
   
   Try to stand in a high place, like atop a hill or a few floors up in a building.
   
   If this isn’t possible, try to find a spot where no other objects are in between you and the object you are focusing on.
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   Step 2: Estimate the horizontal length of the object.

   Here are some standard lengths that may help you:
   Most average-sized cars are between 12 and 15 feet long.
   
   Mailboxes are usually around
   1.5 feet long.
   
   Mature tree trunks are typically between 1 and 2 feet wide.
   
   The standard length of a trailer pulled by a semi-truck is 50 to 65 feet long. , Aim your arm toward the object, and try to keep it as straight as possible.
   
   Point your thumb up. , Keep standing as still as possible. , Try to keep your head and arm perfectly still., Keeping perfectly still, close your left eye and look through the right eye.
   
   Your thumb will appear to have “jumped” to the left.
   
   This “jumping” phenomenon is called “parallax.”, Did your thumb jump 3 times the length of the object? Half the length? Keep this number in mind.
   
   For example:
   If your thumb jumped 3 times the length of a building that you believe is 100-feet-long, then it jumped 300 feet.
   
   If your thumb jumped half the length of a 14-foot-long car, then it jumped 7 feet. , This will give you the approximate distance you're looking for.
   
   For example:
   If your thumb jumped 3 times the length of a 100-foot building, or about 300 feet (91 m), then you would multiply 300 by 10 to conclude that the building is about 3,000 feet (914 m) away from you.
   
   If your thumb moved half the length of a 14-foot-long car, or about 7 feet (2 m), then you would multiply 7 by 10 to conclude that the car is about 70 feet (21 m) away from you.
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   Step 3: Hold your right arm out in front of you.

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   Step 4: Close your right eye.

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   Step 5: Align the left edge of your right thumb with the right edge of the object.

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   Step 6: Switch eyes.

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   Step 7: Estimate how far the left edge of your thumb jumped.

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   Step 8: Multiply that number (the jump) by 10.

Detailed Guide

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