Find midpoint - Midpoint Calculator

This calculator finds the geographic midpoint (geographic center) for two or more places. For example, The point that lies halfway between Chicago and Los Angeles is located at latitude 38°58'N and longitude 103°52'W, which is a point that lies about 22 miles (35 km) southwest of Limon, Colorado. Perhaps the most interesting feature of the calculator is that after you calculate the coordinates of the midpoint you can view a Google map with a marker pointing at the exact location of the midpoint. How to use it

Check out this free online tool by GeoMidpoint

The Random Point Generator generates one or more points at random locations on the surface of the earth. You can throw one or more virtual darts at a Google map and see where they land at.

Using the midpoint calculator

Add each city, town or other location for which you want to find the midpoint to the Your Places list in any order. The latitude and longitude of the midpoint will be automatically calculated and displayed in the Midpoint box every time you add a location to Your Places. See Help for detailed instructions. You may use any or all of the following three methods to select your locations:

1. Search for place
   A fast search of millions of cities, towns and other places from online geocoder services. Type in a city or town and country/state, for example: London, UK or Atlanta, GA. In the US, Canada and other selected countries you can specify a street address such as: 350 Fifth Ave, New York, NY.
2. Select cities from region, state or country
   The calculator provides you over 3000 world cities to choose from in six geographical regions.
3. Specify latitude and longitude
   Use this option to enter the latitude and longitude for any location. Most common latitude/longitude formats can be used. Lists of multiple latitude and longitude data can be imported from other sources into the calculator.

The Time in city can be used to enter the amount of time that you have spent in each city. If you leave the years, months and days blank then all of your cities will be weighted equally for the calculation, otherwise cities with longer times will be weighted more heavily than cities with shorter times.

The calculator gives you three Calculation methods to choose from. In addition to the standard geographic midpoint method which is based on the center of gravity, The center of distance method finds the exact point that minimizes the combined travel distance from all locations in Your Places. The third method is average latitude/longitude which calculates the mathematical average for the locations in Your Places using a flat earth model. Each method is calculated differently and there are reasons for choosing one method over another.

What it can be used for

Some possible uses for the calculator:

• Select all cities and towns that you have lived in, then view those places on a map along with a marker pointing at your exact average location.
• Find the midpoint of an airline flight between two cities. Note that the flight paths of commercial flights may vary somewhat, and may not pass directly over the true midpoint.
• Trip planning--find a central hub for places you are going to visit.
• Find a center location for a convention or family reunion that will be fair and equitable for those who are traveling.
• Find a central place for a new business or facility that will serve surrounding population centers.
• Find latitude and longitude for millions of cities, towns and other places worldwide.
• Midpoint locations, either with or without geocaches can be visited using GPS units. Please read these GPS guidelines before you start your trip.

How it works

The calculator calculates the true midpoint based on the assumption of a spherical earth. The geographic midpoint for any two points on the earth's surface is located halfway along the great circle route, which is the shortest route that runs between both points, and would be like stretching a string between the two points on a world globe then finding the middle of the string. The geographic midpoint for three or more points on the earth's surface is the center of gravity (center of mass or average location) for all of the points.

To help visualize the concept of geographic midpoint and center of gravity, imagine that a small weight is positioned at the location of various cities on a world globe. Now imagine that the globe is allowed to rotate freely until the most heavily weighted part of the globe is pulled by gravity until it is facing downward. The lowest (and heaviest) part of the globe is the center of gravity and the geographic midpoint for all of the weighted cities. See Calculation methods for a detailed description.

Map projections

A lot of distortion occurs when the earth is projected onto a flat surface, for instance, a map using the Mercator Projection. Because of this distortion, if you plot two points on a flat map along with the corresponding midpoint, you will find that the midpoint is often far out of alignment with the two points. This can be easily illustrated by an example. If you place a ruler on a flat wall map between Phoenix, Arizona and Kabul, Afghanistan, the midpoint for the two cities will appear to be in the Atlantic Ocean a few hundred miles off the tip of Portugal. However, the Geographic Midpoint Calculator gives the true midpoint coordinates of latitude 88°57'N 172°57'W, which is 72 miles (116 km) from the North Pole. You can verify this by stretching a string between the two cities on a world globe.

In general, a true midpoint in the Northern Hemisphere will be farther north than you might expect it to be when viewed on a flat map, and conversely, a true midpoint in the Southern Hemisphere will be farther south than you might expect it to be when viewed on a flat map. For cities that are close together this apparent difference between a spherical earth and a flat map is only slight, but the difference can be great for cities with a lot of longitude separation, such as cities on different continents. Also, the difference increases as you move away from the equator towards the polar regions. So if your calculated midpoint is farther north than you expect or is in some other unexpected location, this is the explanation. Usually, if you take a look at a world globe it will begin to make sense.

Geo Challenge

Can you use your geographical knowledge to answer these questions?

Name the country with the world's lowest birth rate. Hint: It also happens to be the world's smallest independent country with an area of just 10 acres.

Which major US city has had its name most drastically shortened from the time of its original settlement to the present?

View past Geo Challenge questions and answers

Contact and miscellaneous

The data used for the calculations comes from various Sources and may contain inaccuracies and errors. If you find that the data for any city is obviously in error, please report it. Send any questions or comments to the link below.

Contact

GeoMidpoint is asking you to Link to us on a web page or blog. Thank you.

Site resources   Additional resources   Google Maps Mania