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Garmin's Data Field Definitions
for the GPS 12 MAP and GPS III (PLUS) Receivers

~ These likely apply to other Garmin units as well ~

List compiled by Niels Kistrup

with corrections added by Sigurd Humerfelt

Which fields that are available on the different screen pages are described at Sigurd's web site.


No. Data Field Definition
  1.
Altitude
Current altitude.
  2.
Avg Speed
Trip Odom / Trip Timer. Be careful with this one; if you fail to reset the trip values at the beginning of your journey, this value could be very deceiving.
  3.
Bat Timer
Amount of time that the GPS has been on, using the current set of internal batteries.
  4.
Bearing
Direction of the next waypoint. (Dependent on your definition of ‘north’. See Course for more info.) If there is no waypoint, this field is blank.
  5.
Course
Direction of the line connecting your previous waypoint with your next waypoint.
This value is dependent on your definition of north. ‘North’ could be true north, magnetic north, grid north, etc., depending on the GPS setting.
  6.
Dist to Dest
Summary: Given a route, it is the sum of the distances of all of the legs, starting with the distance from your current position to the waypoint designated as Wpt (Next).

Full Definition: Distance to the final waypoint, based on the sum of the distances between the intermediate waypoints (i.e. sum of the legs), NOT the absolute distance (i.e. straight-line distance) to the destination. Blank if there are no waypoints. The first distance being summed is the distance to the nearest waypoint, if you are stationary. If you are not stationary, it is the distance to the waypoint that you are moving toward.

Example: Say that you are between the starting position (START) and the first waypoint (WP01), and are taking a break. You pull out your GPS to determine how much further you have to travel.

Scenario 1. If you are at the halfway mark between START and WP01 or beyond it, the first distance being summed will be the distance from your current position to WP01 (assuming WP01 is the nearest waypoint).

Scenario 2. If you haven’t made it to the halfway mark between START and WP01, the first distance is from your current position to START; thus your total distance will exceed the length of your route.

The 2nd scenario matches the 1st scenario if your GPS had been powered up the entire time, or you were moving toward WP01 when you turned it on.

  7.
Dist to Next
Distance to the next waypoint. Blank if there are no waypoints.
  8.
ETA at Dest
Time of day when the final waypoint is reached, based on the VMG value. As with ETA at Next, it is blank if:
1) There are no waypoints or

2) VMG is zero or negative.

ETA at Dest = Time of Day + Time to Dest.

  9.
ETA at Next
Time of day when the next waypoint is reached, based on the VMG value. Blank if:
1) There is no waypoint or

2) VMG is zero or negative.

ETA at Next = Time of Day + Time to Next.

10.
Max Speed
Maximum value of Speed during the current trip.
11.
Odometer
Distance traveled. This can be reset independently of the trip odometer.
12.
Off Course
Shortest distance from the current position to the line between the previous and next waypoint. (Representing Off Course as a line on a map, it will be perpendicular to the line connecting the waypoints.)
13.
Pointer
Same as Turn, but displayed graphically as an arrow.
14.
Speed
Instantaneous speed over two dimensions. Altitude is not factored in.
15.
Sunrise
Time the sun rises, given your current position.
16.
Sunset
Time the sun sets, given your current position.
17.
Time of Day
Time, as in what your watch says. Make sure the offset is adjusted properly for your longitude.
18.
Time to Dest
Time required to reach the final waypoint, based on the VMG value. Blank if:
1) There are no waypoints or

2) VMG is zero or negative.

Time to Dest = Time to Next + sum of the times between the remaining legs of the route.

19.
Time to Next
Time required to the next waypoint, based on the VMG value. Blank if:
1) There is no waypoint or

2) VMG is zero or negative.

Time to Next = Dist to Next / VMG.

20.
To Course
The direction that you must turn, in degrees, that will put you on the line connecting your previous waypoint with your next waypoint. It will point you to either the point on this line closest to your current position, the next waypoint, or somewhere in between.
21.
Track
Actual compass direction that you are traveling (e.g. if you moving southeast, the Track will be 135.)
This value is dependent on your definition of north. ‘North’ could be true north, magnetic north, grid north, etc., depending on the GPS setting.
22.
Trip Odom
Distance traveled during the active trip.
23.
Trip Timer
Time spent moving during the active trip.
24.
Turn
Relative angle to the next waypoint.

Example: If you are traveling northeast, and your next waypoint is actually west, Turn will be L135. You must spin around 135 to your left, to head for the next waypoint.

25.
User Timer
Elapsed time of the user-set timer.
26.
Voltage
Voltage level of the batteries. (An external battery if that is the power source.)
27.
VMG
Velocity Made Good. Instantaneous speed that you are moving toward your destination.

Example: If the angle between Bearing and Track is either 60 or 300 and your Speed is 4 mph, your VMG is 2 mph. (cos(60) or 0.5, multiplied by 4 mph).

28.
Wpt (Dest)
Name of the destination waypoint.
29.
Wpt (Next)
Name of the next waypoint.

Last corrected 7th March 2003, last updated 1st January 2016.