Latitude and longitude coordinates are often presented in degrees, minutes, and seconds (DMS format), such as 39° 45' 30" (39 degrees, 45 minutes, 30 seconds). However, Surfer requires lat/long input data in decimal degrees format (39.75833°). After the map is created from raw data in decimal degrees, you can change the display of the labels on the map to DMS format (How can I format my lat/long labels in Surfer in degrees/minutes/seconds?).

## How DMS to DD conversion works

Converting from degrees, minutes, and seconds is actually quite easy. Consider the latitude value 39° 25' 30". There are 60 minutes in one degree and 3600 seconds in one degree. To convert minutes and seconds to decimal degrees, divide minutes by 60, divide seconds by 3600, and then add the results to obtain the decimal equivalent. Use the following formula to make the conversion:

**Decimal degrees = Degrees + (Minutes/60) + (Seconds/3600) **

For Example, to convert 39° 25' 30" to decimal degrees

- First, convert minutes and seconds to their degree equivalents and add the results

25'/60 = 0.4167°

30"/3600 = .0083°

and 0.4167° + 0.0083° = 0.425° - Then, add this number to the number of degrees.

39° + 0.425° = 39.425° - So, the final result is:

39° 25' 30" = 39.425°

## How to convert from DMS to DD in Surfer

Surfer makes this process quick and easy with a quick conversion tool in the worksheet! To convert from degrees, minutes, seconds (DMS) to decimal degrees (DD) in Surfer:

- Click
**File | Open in Worksheet.** - In the
**Open**dialog, select your data file and click*Open*. - Click
**Data | Coordinate System | DMS to DD**. - In the
**DMS to DD**dialog: - In the
*Source Columns*section, choose the appropriate longitude column from the*Longitude*dropdown list and choose the appropriate latitude column from the*Latitude*dropdown list. - Choose the formatting of your lat/long columns from the
*DMS format*dropdown list. - In the
*Target Columns*section, choose the desired output columns for the decimal degrees values to be written to. By default these are set to the first two empty columns in the worksheet. - Click
*OK*to create two new columns with the decimal degrees lat/long values.

Once your coordinates are in decimal degrees, you can use the data in Surfer.

*Updated November 1, 2023*

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