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It is designed to convert the two different and distinct methods of co-ordinate nomenclature from one
methodology to the other, and to calculate the distance between two sets of coordinates. Due to the fact
that GPS information is so readily available now for daily weather information, automotive use, aviation,
marine and personal use, many companies have set their own standards as to how that information is
displayed and disseminated.
Either method is very accurate in the native form but converting between them can create substantial error.
When using a hand held GPS for instance, you may have to use the information and convert it to or
from what a GIS map displays. We have created this converter and calculator to take decimal degrees
or degrees and decimal minutes, and convert to the other. In order to establish a point, you MUST have
latitude and longitude coordinates in one form or the other. You must enter both points to get a distance
calculation. If you need to get that information to a degrees, minutes and seconds format, use
the GPS Converter.
The distance calculations and bearing are based on a true spherical model. The different latitude and longitude
formats are as follows:
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Degrees, minutes and seconds (DDD, MM, SS) is the conventional method of presentation. (Latitude is DD while
longitude is DDD.) There is usually a quadrasphere designation as well, such as N, S, E or W, based on the
equator and the prime meridian. For the hemisphere, either North or South, the designation is N or S for
latitude. East of the prime meridian is E (positive) and West of the prime meridian is W (negative).
Negative numbers (in certain situations, Southern latitude is displayed as negative; if you see a negative
latitude, it is South while a negative longitude is West) can also be used to express a quadrasphere
designation. In this converter, we do neither since it does not matter. All numbers are assumed to be
positive as far as entry and are actually determined by the N, S, E or W entry.
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Decimal Degrees is displayed as the degrees in normal value, with both minutes and seconds in decimal
format, as a degree value. There is ONLY a degree designation. (DDD.DDDD) A maximum of 4 decimal places
is adequate.
What is most often known as GPS format (though not all GPS units use it or agree on it...), is displayed
as (DDD,MM.MMMM) in which seconds are converted to decimal minutes, as a minute value. Seconds have the
value of 0 to 60, with 0 and 60 (usually designated as 0 to 59 and then restarting at 0) being the
same value, minutes have the same characteristics and degrees are valid from 0 to 180 and 180 to 0,
(0 and 180 do NOT have the same value) both North and South of the equator, and East and West of the
prime meridian. Now that the designations (and reasons for them) are perfectly clear, here is the set
of formulae if you need to do this manually.
- Degrees Minutes Seconds to Degrees Minutes.m (GPS)
- Degrees = Degrees, Minutes.m = Minutes + (Seconds / 60)
- Degrees Minutes.m to Decimal Degrees
- .d = M.m / 60, Decimal Degrees = Degrees + .d
There are 60 minutes in a degree and 60 seconds in a minute (3600 seconds in a degree), both seconds
and minutes are segments of ARC and not time. There are 360 degrees in a complete circle or sphere
but in all longitude measurements, the total of the degrees is expressed as 2 halves of 180 degrees
each, moving East and West from the prime meridian. East is positive and West is negative. Latitude
is designated as North and South but in 90 degree sectors. North is positive and South is Negative.
It is possible to have a 3 digit degree designation for longitude but only a 2 digit designation for
latitude.
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