GIS feature types, How long is a coordinate degree

How Long is a Coordinate Degree?

February 28, 2017 — Brian Higgins

As previously written, I enjoy writing about topics that interest me.   When the topic doesn’t interest me, I tend to get a little cynical.  In that vein, I’d like to share with you a question that got me thinking: What is the accuracy of each decimal place when a location is provided in decimal degrees? In other words, how long is a coordinate degree?

(Can you tell I am a GIS nerd?)

How long is a coordinate degree? Let’s see examples

The location of the SSP headquarters is 39.5830852 degrees north latitude and 104.8371366 degrees west longitude.  Is that last “2” in the ten-millionth latitude degree place really necessary to find the office?  Let’s dig in …

  • Earth has a circumference of 24,901.92 miles (or 131,482,137.6 feet) at the equator.
  • With 360 individual degrees of latitude, that would mean 69.172 miles (or 365,228.16 feet) lie between each degree.

Using those figures, we can determine what a degree actually means in terms of length.

How long is a coordinate degree in miles? [CHART]

If we break down the latitude degrees into decimal places and the distance between parallel lines, we get a conversion equal to this (Figure 1):

How long is a coordinate degree Figure 1. Distance Between Degree Lines

So, by applying these values in a practical manner:

  • The tens place (691 miles apart) helps one narrow the office location to a region of the United States.  Colorado is 484 miles long (Figure 2).

How long is a coordinate degree Figure 2. State of Colorado

  • The ones place (69 miles apart) just about narrows down the state of Colorado.
  • The tenths place (6.9 miles apart) might get one to the county.  Arapahoe County is about 15 miles wide at its greatest (Figure 3).

How long is a coordinate degree Figure 3. Arapahoe County

  • The hundredths place (.69 miles apart) will help get someone close to the neighborhood.  It is a little over a half mile (as a crow flies) from the office to the Bronco’s Training Facility (Figure 4).

How long is a coordinate degree Figure 4. Distance to Bronco's Training Facility

  • The thousandths place (364 feet apart) should get one to the proper building.  The SSP office building is less than 500 feet wide (Figure 5).

How long is a coordinate degree Figure 5. SSP Office Building

So how many decimal places matter in a coordinate degree?

So … if SSP wanted to provide coordinates for clients to navigate to the office, probably stopping at the thousandths place would suffice.  Want to try it out?

Stop by the SSP headquarters and see us. We’re here:

39.583 degrees north latitude and 104.837 degrees west longitude

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Brian Higgins

Brian Higgins is a Senior Consultant at the Utility & Telecommunications GIS consulting company SSP Innovations in Centennial, Colorado.  He is a certified Geographic Information Systems Professional (GISP) with 22 years of experience in the design and development of GIS systems for the management of municipal infrastructure.

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