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• Part 1 of 2: Understanding latitude and longitude
• Part 2 of 2: Finding the latitude and longitude coordinates on a map

Latitude and longitude are measurements of locations on the globe. If you know how to read latitude and longitude on a map, you can determine the geographic coordinates of any place on the map. While online maps make it easy to determine latitude and longitude at the touch of a button, it is sometimes useful to know how to do this with a regular map as well. To read latitude and longitude correctly, you must first understand the basic concepts behind these measurements. Once you know the basics, you will learn how to point out the latitude and longitude markers on a map and determine the exact locations.

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Part 1 of 2: Understanding latitude and longitude

1. Learn the concept of latitude. Latitude is a measure of the distance north or south of the equator, the imaginary horizontal line around the exact center of the Earth between the two poles. The Earth is divided into 180 lines of latitude on either side of the equator, called parallels. These parallels run horizontally around the Earth, parallel to the equator. 90 of them are north of the equator, while the other 90 are south of the equator.
2. Learn the definition of longitude. Longitude is a measure of the distance east or west of an imaginary vertical line that runs through the center of the globe from the North Pole to the South Pole, the Prime Meridian. Longitudinal lines are a series of vertical lines from the North Pole to the South Pole, also called meridians, because it is noon at the same time at any place hit by the same meridian. There are 360 ​​meridians on either side of the Prime Meridian, 180 of which are east of the Prime Meridian and the other 180 are west of the Prime Meridian.
   • The meridian on the opposite side of the Earth from the first meridian is called the antimeridian.
3. Study the units of measurement used for latitude and longitude. Latitude and longitude are usually expressed in degrees (°), minutes (′), or seconds (″). The total distance from one parallel to another or from one meridian to another is 1 °. For even more precise positioning, each degree can be further divided into 60 minutes, and each minute into 60 seconds (for a total of 3,600 seconds per degree).
   • Latitude and longitude are measured in degrees rather than absolute units of measurement (such as miles or kilometers) because the Earth is spherical. While the distance between latitudes is constant (111.12 km), the shape of the Earth causes the distance between longitudes to decrease as you approach the poles.
4. Measure latitude and longitude from the 0 point. When measuring latitude in both directions, the equator is taken as the starting point, at 0 °. Likewise, the prime meridian is the starting point for longitude measurements, representing 0 ° for the longitude. Each measure of latitude or longitude is expressed in both directions in terms of the distance from the starting point.
   • For example, the North Pole is at 90 ° N, which means it is 90 ° north of the equator.
   • The antimeridian is located 180 ° east or west of the prime meridian.
   • The Great Sphinx of Giza in Egypt is located at 29 ° 58′31 ″ N, 31 ° 8′15 ″ E. This means that it is a little less than 30 ° north of the equator in latitude, and about 31 ° east of the prime meridian in longitude.

Part 2 of 2: Finding the latitude and longitude coordinates on a map

1. Find a map with latitude and longitude lines. Not all maps indicate latitude and longitude.You will most likely find them on maps of large areas, such as atlas maps, or on smaller maps designed to show terrain very accurately, such as topographic maps. If you are in the US, detailed topographic maps of most regions are available through the US Geological Survey.
2. Determine the location you are interested in. View the map and find the feature or area for which you want to know the coordinates. Mark the exact place you are interested in with a pushpin or pencil.
3. Determine the latitude and longitude markers. Latitude is indicated on a map by a series of horizontal, evenly spaced lines running from one side of the map to the other, while longitude is indicated by a series of vertical, evenly spaced lines running from top to bottom. Find the numbers along the edges of the map with coordinates for each line. These are the coordinates of the degree grid.
   • Latitudes are indicated along the east and west sides of the map. Longitudes are indicated on the north and south edges of the map.
   • Depending on the scale of your map, the coordinates can mark fractions of degrees instead of whole degrees. For example, a coordinate may be specified for every minute within a degree, instead of every degree (e.g., 32 ° 0 ′, 32 ° 1 ′, 32 ° 1 ′, etc.).
   • The map should also indicate where the latitude and longitude lie in relation to the equator and the prime meridian (eg North or South, East or West).
   • Don't confuse the latitude and longitude lines with UTM lines, another type of coordinate system commonly found on maps. UTM numbers are usually marked in smaller text (and without degree symbols) along the edges of the map, and UTM grid lines may be marked in a different color than latitude and longitude lines.
4. Use a ruler to mark the latitude of your point. Take a ruler and pencil and mark a horizontal line from your point to the nearest east or west edge of the map. Make sure your line is parallel to the nearest latitude line on the map.
5. Draw another line to mark the length of the point. Use the ruler and pencil to draw a straight vertical line from the same point to the nearest north or south edge of the map. Make sure your line is parallel to the longline.
6. Estimate the latitude and longitude of your point using the coordinates. Depending on the scale of the map, you can estimate the coordinates of your point to the second. See where your latitude and longitude lines intersect the coordinate lines at the edge of the map, and estimate the coordinates by their position relative to the nearest grid numbers.
   • If your map shows seconds, find the second closest to where each line intersects the latitude or longitude scale at the edge of the map. For example, if your line of latitude is approximately 5 ″ above the 32 ° 20′N line, your point will be at a latitude of approximately 32 ° 20′5 ″ N.
   • If your map shows minutes, but not seconds, you can estimate the latitude or longitude within six seconds by dividing the space between the degree grid coordinates into tenths. If your longitude falls about 2/10 to the left of the 120 ° 14′E line, then your longitude is about 120 ° 14′12 ″ E.
7. Combine your measurements to determine the coordinates. Geographic coordinates are where the lines of latitude and longitude meet at one point. Take the latitude and longitude numbers of your point and add them together (for example, 32 ° 20′5 ″ N, 120 ° 14′12 ″ E).