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Converting Degrees Minutes Seconds values to Decimal Degree values

Release 9.2
Last modified November 9, 2006
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About converting from Degrees Minutes Seconds to Decimal Degrees

The following is the simple equation to convert Degrees, Minutes, and Seconds into Decimal Degrees.

DD = (Seconds/3600) + (Minutes/60) + Degrees

In the instructions given below you will convert one field in a table of latitude or longitude values in Degrees, Minutes, and Seconds to Decimal Degrees. It is assumed that the Degrees, Minutes, and Seconds are stored as a string (text), with spaces between the numbers and not containing any symbols. For example the data would be stored as:
25 35 22.3

where 25 is degrees, 35 is minutes and 22.3 is seconds.

The output will be stored in a number field.

How to convert values from Degrees Minutes Seconds to Decimal Degrees

  1. Add the table to ArcMap.
  2. Right-click the table in the table of contents and click open.
  3. Click the Options button and click Add Field.
  4. Type "Lat2" in the Name field.
  5. Click the Type drop-down arrow and click Double from the list.
  6. If "Lat2" is already used as a field name, select a name that is not used.
  7. Click OK.
  8. Right-click the Lat2 field and click Field Calculator.
  9. Click Yes if presented with a message box.
  10. Check the Advanced check box.
  11. Paste the following code into the expression box:
  12. Dim Degrees as Double
    Dim Minutes as Double
    Dim Seconds as Double
    Dim DMS as Variant
    Dim DD as Double
DMS = Split([Latitude])
    Degrees = CDbl(DMS(0))
    Minutes = CDbl(DMS(1))
    Seconds = CDbl(DMS(2))
    DD = (Seconds/3600) + (Minutes/60) + Degrees

    In the sixth line, beginning with 'DMS. . .' The text within the brackets [ ] should be the name of the field holding the latitude values. Replace the word Latitude in the code with the name of the field (in your table) that stores the DMS latitude values in the table.
  13. Paste the following code into the 'Lat2 =' box at the bottom of the dialog box.
  14. CDbl(DD)

  15. Click OK.
  16. Repeat steps 3 through 12 for the longitude values.

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