Geographic Midpoint Help
The Geographic Midpoint Calculator finds the geographic midpoint for two or more places. The calculator provides three methods for selecting addresses, cities, towns and other geographic locations.
This option allows you to enter your addresses, cities, or other places into the calculator one by one. If your places are successfully located in the Google geocoding service, the locations are added to the 'Your places' list and corresponding markers are displayed on the map. The geographic midpoint (center of gravity) is also automatically computed and displayed on the map if there are two or more places.
- Select the 'Address' option.
In the 'Address or City' box type the name of the address, city, and country/state separated by a comma, for example:
350 Fifthe Ave, New York, NY
- (Optional) You may weight each of your addresses by time for the personal center of gravity calculation. Enter the time you have lived in each location in any combination of years, months and days. The 'Other weight' option allows you to assign other weighting factors such as population for the calculation. If you leave the years, months, days and weight blank then all of your locations will be weighted equally for the calculation.
- Click on 'Add'. Your address is added to the 'Your places' list and a red marker points at your location on the map. In some cases more than one search result will be found matching the name of the place you entered. select the location that you desire and click ok.
- Repeat steps 2-4 to add additional locations to the map.
- Click on the M marker to see latitude, longitude and other information for the midpoint.
B. Multiple input
With this time-saving option you can copy a list of addresses from a spreadsheet or other program then paste the list into the calculator. If you want to watch the process of markers being added to the map, recenter the map and adjust the zoom level to view your region of interest before starting.
- Select the option "Multiple input'.
- Select and copy the column containing your addresses from your spreadsheet or other program, then paste it into the 'Addresses' box in the calculator. Each address must be on a separate line. If any address wraps to a second line, shorten it by using state or country abbreviations or by removing apartment and suite information from the address.
- (Optional) If you want to use weighting factors, copy and paste the appropriate data into the 'Years', 'Months', 'Days', or 'Weight' boxes.
- Click on 'Add'. The calculator begins to retrieve the information for your locations from the Google geocoding service. The retrieved locations are placed in the 'Your places' list and displayed on the map. Occasionally, the calculator may stop and ask you to clarify which address you want to use. Select the one you desire then click 'Ok'. If you have hundreds or even thousands of locations to geocode there are geocoding limits and time considerations to be aware of.
- After the calculator finishes geocoding all addresses, the midpoint is displayed on the map. Click on the M marker to see information for the midpoint.
- Select 'Latitude/longitude'.
- Enter one or more latitudes and longitudes into the 'Latitude' and 'Longitude' boxes using one of the allowed formats. As an alternative, you can copy lists of latitudes and longitudes and paste them into these boxes. In all cases the number of latitudes and longitudes must be equal.
- (Optional) If desired, type in, or copy and paste in the data for weighting factors as described above.
- Click on 'Add'. The locations are added to the 'Your places' list and plotted on the map.
- After all locations have been added, the midpoint is displayed on the map. Click on the M marker to see information for the midpoint.
You can use any combination of the above three methods when specifying locations for the calculator.
The calculator provides you three Calculation methods to choose from. The geographic midpoint finds the center of gravity, center of minimum distance finds the exact point that minimizes the combined travel distance from all locations in 'Your Places' and average latitude/longitude finds the mathematical average for all locations in 'Your Places'. There are reasons for choosing one method over another.
Geocoder limits and time considerations
Google has set a limit of 2,500 geocode requests per day for your computer's IP address. Be aware also that adding hundreds of markers or more to a map will greatly slow down most browsers. The speed at which you can process large numbers of addresses depends on the speed of your connection, the speed of your computer, and which browser you are using. If you have a lot of addresses to add to the map you may wish to uncheck the checkbox labeled "Display place markers'. Doing this will calculate the midpoint for all places and add only the M marker to the map which speeds up the process considerably.
Saving a map
By using the 'Save map' option, you can save your map along with the midpoint marker and a moderate number of red place markers in your Favorites/Bookmarks. Typically, from 25 to 75 place markers can be saved, depending on your browser and the amount of data being saved.