This tool is to help get GPS Coordinates in wildland fire preffered format. I’m hoping to add this tool into the Wildland Fire Study App. Thank you for visiting.

For the App This section Can be an Expandable Button Below the main GPS app.

A Brief History of GPS Coordinate Formats

Before GPS

Long before satellites, navigators located positions on Earth using latitude and longitude, a system dating back to the ancient Greeks. Around 150 AD, the astronomer and geographer Claudius Ptolemy published maps using latitude and longitude, laying the foundation for modern navigation.

As surveying and mapping improved over the centuries, coordinates were commonly expressed in:

• Degrees (°)
• Minutes (‘)
• Seconds (“)

This became known as Degrees, Minutes, Seconds (DMS).

Example:
34° 15′ 32.4″ N
111° 45′ 18.7″ W

---

GPS Arrives (1970s–1990s)

The U.S. Department of Defense developed the Global Positioning System (GPS) during the 1970s. Civilian GPS receivers became common in the late 1980s and 1990s.

Computers calculate locations using decimal numbers, so manufacturers began displaying coordinates in formats easier for computers to process than traditional DMS.

This led to three primary coordinate formats that remain common today.

---

1. Decimal Degrees (DD)

Example:

34.25896°
-111.75519°

History

Decimal Degrees became popular with:

• Computer mapping
• GIS software
• Google Earth
• Google Maps
• Smartphones

Instead of dividing coordinates into minutes and seconds, everything is converted into a decimal.

Advantages

• Simplest for computers
• Easy calculations
• Easy import/export
• Preferred for web mapping

Common Uses

• Google Maps
• Apple Maps
• GIS programs
• Drones
• APIs
• Modern smartphones

---

2. Degrees Decimal Minutes (DDM)

Example:

34° 15.5376′ N
111° 45.3114′ W

Sometimes written as:

3415.5376N
11145.3114W

History

As handheld GPS receivers became popular in the 1990s, many manufacturers chose DDM because it balanced precision with readability.

Instead of:

• Degrees
• Minutes
• Seconds

the seconds were converted into a decimal portion of the minutes.

Advantages

• Faster to read over the radio
• Easier to enter manually
• Fewer numbers than DMS
• Very accurate

Common Uses

• Marine navigation
• Aviation
• Search and Rescue
• Wildland Fire
• Military GPS units
• Garmin handhelds

This is the format used throughout much of the U.S. wildland fire community because it reduces transcription errors during radio communications.

Example radio transmission:

“Latitude three four degrees one five point five three seven six North.”

---

3. Degrees Minutes Seconds (DMS)

Example:

34° 15′ 32.3″ N
111° 45′ 18.7″ W

History

This is the oldest coordinate format, dating back centuries.

Paper maps, nautical charts, and early surveying all used DMS.

Even today, many official maps continue to print coordinates this way.

Advantages

• Traditional
• Human-readable
• Common on printed maps

Common Uses

• Surveying
• Land ownership
• Paper maps
• Some military applications
• Historical records

---

Why Different Formats Exist

All three formats represent the same physical location. They simply express the coordinate differently.

Example of the same point:

Format	Example
DD	34.25896°, -111.75519°
DDM	34° 15.5376′, 111° 45.3114′ W
DMS	34° 15′ 32.3″, 111° 45′ 18.7″ W

---

Which Format Does Google Maps Use?

Google Maps primarily uses Decimal Degrees (DD) internally and displays coordinates in DD by default.

Example:

34.258960, -111.755190

However, Google Maps can accept searches entered in:

• Decimal Degrees (DD)
• Degrees Decimal Minutes (DDM)
• Degrees Minutes Seconds (DMS)

and will convert them automatically.

---

Which Format Does Wildland Fire Use?

Most U.S. wildland fire agencies use Degrees Decimal Minutes (DDM) for field operations.

Example:

N 34° 15.538′
W 111° 45.311′

Reasons include:

• Easy to read over the radio
• Works well with handheld GPS units
• Compatible with aviation resources
• Reduces mistakes when communicating coordinates
• Standardized in many incident operations

---

Quick Comparison

Format	Example	Best For
DD	34.25896, -111.75519	Google Maps, smartphones, GIS, apps
DDM	34° 15.538′, 111° 45.311′	Wildland fire, aviation, marine navigation, search and rescue
DMS	34° 15′ 32.3″, 111° 45′ 18.7″	Paper maps, surveying, historical mapping

Wildland GPS Field Cheat Sheet

Apps Commonly Used

• Avenza Maps – Usually displays coordinates in Degrees Decimal Minutes (DDM).
• Esri Field Maps – Coordinate display can be changed between DD, DDM, and DMS.
• OnX – Supports multiple coordinate formats in Settings.

---

Rule of 60

• Multiply by 60 when moving DOWN: Degrees → Minutes → Seconds.
• Divide by 60 when moving UP: Seconds → Minutes → Degrees.
• Seconds directly to Degrees = divide by 3600.

---

Quick Conversions

• DD → DDM: Decimal portion × 60 = Decimal Minutes.
• DDM → DD: Decimal Minutes ÷ 60.
• DDM → DMS: Decimal portion of Minutes × 60 = Seconds.
• DMS → DDM: Seconds ÷ 60, then add to Minutes.
• DMS → DD: Degrees + (Minutes ÷ 60) + (Seconds ÷ 3600).

---

Easy Field Examples

• Quarter Minute: 34° 15.25′ = 34° 15′ 15″
• Half Minute: 34° 15.50′ = 34° 15′ 30″
• Three-Quarter Minute: 34° 15.75′ = 34° 15′ 45″

---

Speaking Coordinates Over the Radio (DDM)

• State the format first if there is any doubt:
  • “Coordinates are Degrees Decimal Minutes.”
• Latitude example:
  • “Three Four degrees, One Five decimal Two Five North.”
• Longitude example:
  • “One One One degrees, Four Seven decimal Five Zero West.”
• Repeat the coordinate back for confirmation before ending the transmission.
• Always include North/South and East/West (or give Latitude followed by Longitude).