American Bushman

"If you would not be forgotten as soon as you are dead, either write things worth reading or do things worth writing." —Benjamin Franklin

Tuesday, March 04, 2008

Estimating Angles by Hand

When in the wilderness you sometimes need to take measurements and may not have the necessary tools in your pockets or pack. Fortunately we're equipped with tools for estimation--our hands.

Taking some time to measure the length of your finger, the distance from thumb to index finger, etc. can pay off when you need to estimate the size of a peak, a tree, or a distant object.

Today we're going to look at angles and their use in estimating available sunlight.

Holding your hand parallel to the horizon you can get a fairly accurate estimate of how much daylight is left by working your way from the horizon to the sun. Each four-finger width is approximately one hour which makes each finger approximately 15 minutes. This is an important skill to have when you are going to be prioritizing shelter building, firewood collection, fire building, etc.

2 degrees or 15 minutes
4 degrees or 30 minutes
6 degrees or 45 minutes
15 degrees
20 degrees
8 degrees or an hour

Using these estimates and a bit of math you can also calculate distance. A finger held at arm's length covers approximately 2 degrees, two fingers approximately 4 degrees, and so on. To estimate your distance from an object of known width or distance use this formula:

width or distance in feet / 100 X angle = approximate distance in miles.

As an example:

You know a particular tree to be four feet in width and, from your current position, with a hand held at arm's length, you can cover that tree with a single finger (2 degrees.)

Using the formula, 4 (feet in width of the tree) / (100 X 2) = .02

or 2/10 of a mile to the tree.

A "handy" (yes, pun intended) method of calculating distance and hours of remaining daylight don't you think?

Thanks for reading,



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