For convenience in locating the geographic position of different places on the Earth’s surface, the surface is covered by an imaginary grid, which is depicted on maps as vertical and horizontal lines. The vertical lines, which join the two poles, are called lines of longitude, and the horizontal lines, which are parallel to the equator, are called lines of latitude.
Longitude is split into 360 degrees, 180 degrees to the east and to the west of Greenwich, through which the Zero degree meridian passes. Latitude is split into 180 degrees, 90 degrees north and south of the equator.
Knowing how to calculate the difference in latitude, calculator or not, can help determine distances between points.
Determine the Latitude
In order to calculate the difference in latitude of two places, you first need to know the latitude of each of the two individual locations. There are several ways of determining this.
The traditional way is to look up the location on a map that shows latitude and longitude and to measure the latitude using a pair of dividers.
The second, and probably the easiest way, is to look it up on an Internet search, and the third is to use a program such as Google Earth, and read it off the screen.
Distance Between Two Coordinates: Making the Calculation
Here’s where your math is put to test. If both locations are on the same side of the equator, then you must deduct the smaller figure from the larger. If they are on opposite sides of the equator, then you must add the two figures together.
Forget about any minus signs that you may see -- they just signify that the figure is the number of degrees to the south of the equator.
Example Distance Calculator
As an example you can use Denver, Colorado, and Albuquerque, New Mexico. Looking up Denver will give you 39.74 degrees and Albuquerque will give 35.11 degrees. Take the smaller away from the larger to get the difference.
39.74 degrees - 35.11 degrees = 4.74 degrees
4.74 degrees is the difference in latitude.
As another example you can use Denver (again) and Buenos Aires. Denver, once again, is 39.74 degrees and Buenos Aires is -34.61 degrees south of the equator. You still take the difference of the two, but since Buenos Aries is at a negative latitude, the double negative creates a positive.
39.74 degrees - -34.61 degrees = 39.74 degrees + 34.61 degrees = 74.35 degrees
So, adding the two figures together gives a latitude difference of 74.35 degrees.
Converting Latitude Difference to Miles
Since knowing the number of degrees difference may not mean much to many people, you may want to convert the figure into miles. You’ll probably need a distance calculator for this. The general conversion factor is one degree of latitude is the equivalent of 60 nautical miles.
For example, taking the second example with Denver and Buenos Aries. You'll take the difference in latitude, which is the distance between the two locations, and you multiple it by the conversion factor of 1 degree / 60 nautical miles. This looks like this:
74.35 degrees * (60 nautical miles / 1 degree) = 4,461 nautical miles
This gives you an answer in miles of 4,461 nautical miles. If you want this answer in everyday American miles, you must further convert. The conversion factor for nautical miles to miles is 1 nautical mile = 1.150782 miles. Continuing with the Denver and Buenos Aries example, your calculation would look like this:
4,461 nautical miles * (1.150782 miles / 1 nautical mile) = 5,130 miles
This gives you a final answer that Buenos Aires is 5,130 miles to the south of Denver.
About the Author
Michael Mason started content writing in 2006. He has had articles published on Yachting.com, Biking.com and Skiers.com. He was educated at Bromsgrove School in England and at Britannia Royal Naval College, Dartmouth, England, where he graduated as a naval officer and majored in air warfare and navigation. He is a retired naval aviator.